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1.  Cardiovascular evaluation, including resting and exercise electrocardiography, before participation in competitive sports: cross sectional study 
Objective To evaluate the clinical usefulness of complete preparticipation cardiovascular screening in a large cohort of sports participants.
Design Cross sectional study of data over a five year period.
Setting Institute of Sports Medicine in Florence, Italy.
Participants 30 065 (23 570 men) people seeking to obtain clinical eligibility for competitive sports.
Main outcome measures Results of resting and exercise 12 lead electrocardiography.
Results Resting 12 lead ECG patterns showed abnormalities in 1812 (6%) participants, with the most common abnormalities (>80%) concerning innocent ECG changes. Exercise ECG showed an abnormal pattern in 1459 (4.9%) participants. Exercise ECG showed cardiac anomalies in 1227 athletes with normal findings on resting ECG. At the end of screening, 196 (0.6%) participants were considered ineligible for competitive sports. Among the 159 participants who were disqualified at the end of the screening for cardiac reasons, a consistent proportion (n=126, 79.2%) had shown innocent or negative findings on resting 12 lead ECG but clear pathological alterations during the exercise test. After adjustment for possible confounders, logistic regression analysis showed that age >30 years was significantly associated with an increased risk of being disqualified for cardiac findings during exercise testing.
Conclusions Among people seeking to take part in competitive sports, exercise ECG can identify those with cardiac abnormalities. Follow-up studies would show if disqualification of such people would reduce the incidence of CV events among athletes.
doi:10.1136/bmj.a346
PMCID: PMC2453296  PMID: 18599474
2.  Noninvasive Cardiac Screening in Young Athletes With Ventricular Arrhythmias 
The American Journal of Cardiology  2013;111(4):557-562.
The aim of this study was to analyze using noninvasive cardiac examinations a series of young athletes discovered to have ventricular arrhythmias (VAs) during the preparticipation screening program for competitive sports. One hundred forty-five athletes (mean age 17 ± 5 years) were evaluated. The study protocol included electrocardiography (ECG), exercise testing, 2-dimensional and Doppler echocardiography, 24-hour Holter monitoring, signal-averaged ECG, and in selected cases contrast-enhanced cardiac magnetic resonance imaging. Results of ECG were normal in most athletes (85%). VAs were initially detected prevalently during exercise testing (85%) and in the remaining cases on ECG and Holter monitoring. Premature ventricular complexes disappeared during exercise in 56% of subjects. Premature ventricular complexes during Holter monitoring averaged 4,700 per day, predominantly monomorphic (88%), single, and/or in couplets (79%). The most important echocardiographic findings were mitral valve prolapse in 29 patients (20%), congenital heart disease in 4 (3%), and right ventricular regional kinetic abnormalities in 5 (3.5%). On cardiac magnetic resonance imaging, right ventricular regional kinetic abnormalities were detected in 9 of 30 athletes and were diagnostic of arrhythmogenic right ventricular cardiomyopathy in only 1 athlete. Overall, 30% of athletes were judged to have potentially dangerous VAs. In asymptomatic athletes with prevalently normal ECG, most VAs can be identified by adding an exercise test during preparticipation screening. In conclusion, cardiac screening with noninvasive examinations remains a fundamental tool for the identification of a possible pathologic substrate and for the characterization of electrical instability.
doi:10.1016/j.amjcard.2012.10.044
PMCID: PMC3569714  PMID: 23219000
3.  Assessment of electrocardiography, echocardiography, and heart rate variability in dynamic and static type athletes 
Background:
Over the last two decades, morphological cardiac changes induced by athletic conditioning have been of great interest. Therefore, several studies have been orchestrated to delineate electrocardiography (ECG), echocardiography, and heart rate variability (HRV) findings in athletes.
Purpose:
To assess the ECG, echocardiography, and HRV in a group of dynamic and static type athletes.
Methods:
Fifty professional athletes (20 static and 30 dynamic exercise athletes) and 50 healthy nonathletes (control group) were recruited. Standard 12-lead ECG and transthoracic echocardiography was performed on all athletes and the control group. Through echocardiography, variables including left ventricular (LV) end-diastolic/systolic diameter, LV mass, and left atrial volume index were measured. In addition, both the athletes and the control group underwent ECG Holter monitoring for 15 minutes and several parameters related to HRV (time and frequency domain) were recorded.
Results:
The most common ECG abnormalities among the athletes were sinus bradycardia and incomplete right bundle branch block. LV end-diastolic diameter and left atrial volume index were significantly greater in the dynamic athletes (P < 0.001). LV end-systolic diameter was significantly lower in the static group (P < 0.001). LV mass of the dynamic and static athletes was significantly greater than that of the controls (P < 0.001). Among the ECG Holter monitoring findings, the dynamic athletes had lower systolic blood pressure than the controls (P = 0.01). Heart rate was lowest in the control group (P < 0.001).
Conclusion:
The most common ECG abnormalities among adolescent Iranian athletes were sinus bradycardia and incomplete right bundle branch block. Static exercise seemed to reduce LV end-systolic diameter, while dynamic exercise resulted in increased LV end-diastolic diameter and left atrial volume index. Additionally, Iranian athletes showed no differences in HRV parameters, excluding heart rate and systolic blood pressure, compared with the nonathletes.
doi:10.2147/IJGM.S33247
PMCID: PMC3422899  PMID: 22924010
athlete’s heart; electrocardiography; echocardiography; heart rate variability
4.  Pre-participation Cardiovascular Screening of Elderly Wrestlers 
Purpose
Sudden death of a competitive athlete is a tragedy that is usually caused by a previously unsuspected cardiovascular disease. The aim of this study was to clarify the role of noninvasive testing in pre-participation cardiovascular evaluation of elderly wrestlers.
Methods
We included 63 Iranian elderly wrestlers who participated in Tehran international elderly wrestlers’ preparation camping by census method. A questionnaire including past medical and family history as well as coronary risk factors was filled out and then a complete physical examination of the cardiovascular system was done by an internist for all wrestlers. Electrocardiogram (ECG), complete echocardiographic examination and then symptom limited exercise test were performed and reported by the cardiologists who did not know the other examinations results.
Results
Exertional dyspnea and typical chest pain (FC=I or II) were present in 5% and 1.7% of the examinees, respectively. There were one or more risk factors in 64.5% of the cases. Cardiovascular examination revealed abnormal heart sounds in 27.1%. ECG showed ischemic changes in 13.6% and premature atrial contractions and premature ventricular contractions in 11.4%. Echocardiography showed mild left ventricular systolic dysfunction in 3.4%, regional wall motion abnormality in 8.5%, valvular disease in 32.3%, diastolic dysfunction in 45.7%, and left ventricular hypertrophy in 16.9% of the cases. Exercise test results were negative, equivocal, positive and highly positive in 70.4%, 15.8%, 5.2%, and 8.6% of cases, respectively.
Conclusion
Beside physical examination, pre-participation screening of elderly wrestling athletes with ECG and exercise testing is feasible and recommended in the presence of coronary risk factors or cardiac symptoms. Echocardiography can also be recommended to detect other relevant abnormalities when there is a clue in the standard history, physical examination or ECG.
PMCID: PMC3289166  PMID: 22375189
Wrestling; Cardiovascular disease; Elderly wrestler; Screening; Pre-participation examination
5.  Electrocardiogram Testing During Athletic Preparticipation Physical Examinations 
Journal of Athletic Training  2010;45(3):265-272.
Abstract
Context:
Sudden cardiac death (SCD) is a relatively rare yet unfortunate risk of athletic participation. To reduce the incidence of SCD, electrocardiogram (ECG) use during athletic preparticipation examinations (PPEs) has been proposed to detect underlying cardiac abnormalities.
Objective:
To estimate the effectiveness of ECG use during athletic PPEs.
Design:
Epidemiologic modeling.
Populations:
Public high school athletes.
Data Collection and Analysis:
Estimates of ECG sensitivity (70%) and specificity (84%) were drawn from the literature, as was the estimate of overall prevalence of cardiac conditions relevant to SCD (0.3%). Participation rate by sex was determined from National Federation of State High School Associations data. Participation by ethnicity was assumed to be proportionate to the public high school attendance rates for grades 9 through 12 (18.4% African American). Population-specific ECG effectiveness (positive predictive value), estimated total costs, cost per year of life saved, and cost to identify 1 additional case were computed. Total annual PPE screening costs reflected a cardiologist's office visit, including echocardiogram for those athletes with a positive ECG screen.
Results:
The model predicted that 16% of all athletes would be expected to have a positive ECG, but only 1.3% of athletes with a positive ECG would have a cardiac abnormality capable of causing SCD, including hypertrophic cardiomyopathy, structural defects, and various conduction abnormalities. Total annual cost estimates for ECG screening and follow-up exceeded $126 million. Average cost per year of life saved across groups was $2693, and the cost to identify 1 additional case averaged $100 827. Compared with females, males had both lower cost per year of life saved and lower cost to identify 1 true case. Similarly, black males exhibited lower costs than white males. Across groups, false-positive ECG screening exams accounted for 98.8% of follow-up costs.
Conclusions:
Large-scale, mass ECG testing would be a costly method to identify athletes with cardiac abnormalities. Targeting high-risk populations can increase the effectiveness of the ECG for athletic PPE screening.
doi:10.4085/1062-6050-45.3.265
PMCID: PMC2865965  PMID: 20446840
cardiac abnormalities; sudden cardiac death; prevalence
6.  Association of Early Repolarization Pattern on ECG with Risk of Cardiac and All-Cause Mortality: A Population-Based Prospective Cohort Study (MONICA/KORA) 
PLoS Medicine  2010;7(7):e1000314.
In a population-based cohort study of middle-aged people in Central Europe, Stefan Kääb and colleagues find an association between electrocardiographic early repolarization pattern and mortality risk.
Background
Early repolarization pattern (ERP) on electrocardiogram was associated with idiopathic ventricular fibrillation and sudden cardiac arrest in a case-control study and with cardiovascular mortality in a Finnish community-based sample. We sought to determine ERP prevalence and its association with cardiac and all-cause mortality in a large, prospective, population-based case-cohort study (Monitoring of Cardiovascular Diseases and Conditions [MONICA]/KORA [Cooperative Health Research in the Region of Augsburg]) comprised of individuals of Central-European descent.
Methods and Findings
Electrocardiograms of 1,945 participants aged 35–74 y, representing a source population of 6,213 individuals, were analyzed applying a case-cohort design. Mean follow-up was 18.9 y. Cause of death was ascertained by the 9th revision of the International Classification of Disease (ICD-9) codes as documented in death certificates. ERP-attributable effects on mortality were determined by a weighted Cox proportional hazard model adjusted for covariables. Prevalence of ERP was 13.1% in our study. ERP was associated with cardiac and all-cause mortality, most pronounced in those of younger age and male sex; a clear ERP-age interaction was detected (p = 0.005). Age-stratified analyses showed hazard ratios (HRs) for cardiac mortality of 1.96 (95% confidence interval [CI] 1.05–3.68, p = 0.035) for both sexes and 2.65 (95% CI 1.21–5.83, p = 0.015) for men between 35–54 y. An inferior localization of ERP further increased ERP-attributable cardiac mortality to HRs of 3.15 (95% CI 1.58–6.28, p = 0.001) for both sexes and to 4.27 (95% CI 1.90–9.61, p<0.001) for men between 35–54 y. HRs for all-cause mortality were weaker but reached significance.
Conclusions
We found a high prevalence of ERP in our population-based cohort of middle-aged individuals. ERP was associated with about a 2- to 4-fold increased risk of cardiac mortality in individuals between 35 and 54 y. An inferior localization of ERP was associated with a particularly increased risk.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
Cardiovascular diseases—disorders that affect the heart and the circulation—are the leading cause of death in the developed world. About half of cardiovascular deaths occur when the heart suddenly stops pumping (sudden cardiac arrest). The muscular walls of the four heart chambers contract in a set pattern to pump blood around the body. The heart's internal electrical system controls the rate and rhythm of these contractions and, if this system goes wrong, an abnormal heart beat or “arrhythmia” develops. Some arrhythmias—in particular, ventricular fibrillation in which the walls of the two lower heart chambers quiver or “fibrillate” instead of pumping—can cause sudden cardiac arrest and immediate loss of consciousness. Death follows within minutes in 95% of cases but immediate cardiopulmonary resuscitation (CPR; chest compression to pump the heart and inflation of the lungs by mouth-to-mouth resuscitation) can keep a person alive until a defibrillator can be used to restore the normal heart beat. People who survive sudden cardiac arrest can be given anti-arrhythmia drugs or have a pacemaker implanted to stabilize their heart beat.
Why Was This Study Done?
The beating heart generates tiny electric waves that can be detected by electrodes on the skin. The pattern of these waves (an electrocardiogram or ECG) provides information about the heart's health. One wave pattern that is often seen on ECGs is the “early repolarization pattern” (ERP), which some studies suggest is associated with an increased risk of cardiac death. Here, the researchers investigate the prevalence of ERP (the proportion of a population with ERP) and its association with death from heart-related problems (cardiac mortality) and from any cause (all-cause mortality) in the MONICA/KORA prospective, population-based case-cohort study. The MONICA Project (MONitoring of Trends and Determinants in CArdiovascular Disease) has studied cardiovascular disease in 10 million people in 21 countries; KORA denotes the study done in the Augsburg region of Germany. In a prospective study, specific baseline characteristics of the study's participants are determined and the participants are followed to see who experiences a predefined outcome. A case-cohort study investigates a randomly selected subcohort (subgroup) of the original participants of a study and any participants who experience the predefined outcome instead of all the participants.
What Did the Researchers Do and Find?
The researchers selected 1945 MONIKA/KORA participants aged 35–74 years from a source population of about 6,000 people using a case-cohort study design. They analyzed the ECGs (recorded in 1984–1985 or 1989–1990) of this subcohort and ascertained the cause of death for those participants who died during the 18.9 year average follow-up. The overall prevalence of ERP in the study was 13.1%, report the researchers, and ERP was associated with cardiac mortality, particularly among younger and male participants. Specifically, among men and women aged 35–54 years, having ERP was associated with a nearly doubled risk of cardiac death. Among men aged 35–54 years, having ERP was associated with an increase in the risk of cardiac death by 2.65-fold. An ERP localized to the bottom of the heart (inferior localization) was associated with an increased risk of cardiac death among both sexes by more than 3-fold and among men by more than 4-fold in this age group. Finally, ERP was also significantly associated with an increased risk of all-cause mortality but less strongly than with cardiac mortality.
What Do These Findings Mean?
These findings suggest that the prevalence of ERP among the middle-aged people in the MONICA/KORA study is high (and somewhat higher than previously reported). They also show a clear association between ERP and the risk of cardiac death among 35–54-year-old people, particularly among men, but because of the study design, these findings do not show that ERP actually causes cardiac death; it could simply be a susceptibility marker. The researchers note that the increased risk of cardiac death associated with ERP is of a similar size to that associated with some other ECG abnormalities. However, although it might be worth paying special attention to young people with an inferior localization of ERP, finding ERP in a person without symptoms and without a family history of sudden cardiac death should not lead to further investigations or any preventative therapy, they suggest, because the absolute risk of cardiac arrest in such people is very low.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000314.
The US National Heart Lung and Blood Institute provides information on cardiovascular conditions, including sudden cardiac arrest and on arrhythmias
The American Heart Association also information on sudden cardiac death and on arrhythmias
The German Cardiac Society (Deutsche Gesellschaft fr Kardiologie) and the German Heart Foundation (Deutsche Herzstiftung) provide further information (in German) on cardiovascular conditions
The Heart Rhythm Foundation provides information on all aspects of heart arrhythmia
The Fondation Leducq Alliance Against Sudden Cardiac Death provides information on sudden cardiac arrest
MedlinePlus provides links to other resources about cardiac arrest and arrhythmias (in English and Spanish)
The MedlinePlus Encyclopedia has a page on electrocardiograms (in English and Spanish)
The Nobel Foundation provides an interactive electrocardiogram game
More information about the MONICA project and the KORA Study or is available
doi:10.1371/journal.pmed.1000314
PMCID: PMC2910598  PMID: 20668657
7.  Prevalence of electrocardiographic abnormalities in West-Asian and African male athletes 
Objectives
To evaluate the electrocardiographic (ECG) characteristics of West-Asian, black and Caucasian male athletes competing in Qatar using the 2010 recommendations for 12-lead ECG interpretation by the European Society of Cardiology (ESC).
Design
Cardiovascular screening with resting 12-lead ECG analysis of 1220 national level athletes (800 West-Asian, 300 black and 120 Caucasian) and 135 West-Asian controls was performed.
Results
Ten per cent of athletes presented with ‘uncommon’ ECG findings. Black African descent was an independent predictor of ‘uncommon’ ECG changes when compared with West-Asian and Caucasian athletes (p<0.001). Black athletes also demonstrated a significantly greater prevalence of lateral T-wave inversions than both West-Asian and Caucasian athletes (6.1% vs 1.6% and 0%, p<0.05). The rate of ‘uncommon’ ECG changes between West-Asian and Caucasian athletes was comparable (7.9% vs 5.8%, p>0.05). Seven athletes (0.6%) were identified with a disease associated with sudden death; this prevalence was two times higher in black athletes than in West-Asian athletes (1% vs 0.5%), and no cases were reported in Caucasian athletes and West-Asian controls. Eighteen West-Asian and black athletes were identified with repolarisation abnormalities suggestive of a cardiomyopathy, but ultimately, none were diagnosed with a cardiac disease.
Conclusion
West-Asian and Caucasian athletes demonstrate comparable rates of ECG findings. Black African ethnicity is positively associated with increased frequencies of ‘uncommon’ ECG traits. Future work should examine the genetic mechanisms behind ECG and myocardial adaptations in athletes of diverse ethnicity, aiding in the clinical differentiation between physiological remodelling and potential cardiomyopathy or ion channel disorders.
doi:10.1136/bjsm.2010.082743
PMCID: PMC3329226  PMID: 21596717
8.  Role of exercise stress test in master athletes 
Background: The effectiveness of cardiovascular screening in minimising the risk of athletic field deaths in master athletes is not known.
Objective: To evaluate the prevalence and clinical significance of ST segment depression during a stress test in asymptomatic apparently healthy elderly athletes.
Methods: A total of 113 male subjects aged over 60 were studied (79 trained and 34 sedentary); 88 of them (62 trained and 26 sedentary) were followed up for four years (mean 2.16 years for athletes, 1.26 years for sedentary subjects), with a resting 12 lead electrocardiogram (ECG), symptom limited exercise ECG on a cycle ergometer, echocardiography, and 24 hour ECG Holter monitoring.
Results: A significant ST segment depression at peak exercise was detected in one athlete at the first evaluation. A further case was seen during the follow up period in a previously "negative" athlete. Both were asymptomatic, and single photon emission tomography and/or stress echocardiography were negative for myocardial ischaemia. The athletes remained symptom-free during the period of the study. One athlete died during the follow up for coronary artery disease: he showed polymorphous ventricular tachycardia during both the exercise test and Holter monitoring, but no significant ST segment depression.
Conclusions: The finding of false positive ST segment depression in elderly athletes, although still not fully understood, may be related to the physiological cardiac remodelling induced by regular training. Thus athletes with exercise induced ST segment depression, with no associated symptoms and/or complex ventricular arrhythmias, and no adverse findings at second level cardiological testing, should be considered free from coronary disease and safe to continue athletic training.
doi:10.1136/bjsm.2004.014340
PMCID: PMC1725270  PMID: 16046336
9.  Cost effectiveness of pre-participation screening for prevention of sudden cardiac death in young athletes 
Annals of internal medicine  2010;152(5):276-286.
Background
Inclusion of a 12-lead electrocardiogram in the preparticipation screening of young athletes is controversial in large part due to concerns over cost-effectiveness.
Objective
To evaluate the cost-effectiveness of electrocardiography plus cardiac-focused history and physical and history and physical for preparticipation screening.
Design
Decision analysis cost-effectiveness model.
Data Sources
Published epidemiologic and preparticipation screening data, vital statistics, other publicly available data.
Target Population
High school and college competitive athletes ages 14 to 22
Time Horizon
Lifetime.
Perspective
Societal.
Interventions
Non-participation in competitive athletic activity and disease-specific treatment for identified athletes with heart disease.
Outcome Measures
Incremental health care cost per life year gained.
Results of Base-Case Analysis
The addition of electrocardiography to pre-participation screening saves 2.06 life years per 1000 athletes at an incremental total cost of $89 per athlete, yielding a cost-effectiveness ratio of $42,900 per life year saved (95% confidence interval, $21,200–71,300) when compared with cardiac-focused history and physical alone and saves 2.6 life years per 1000 athletes screened and costs $199 per athlete, yielding a cost-effectiveness ratio of $76,100 per life year saved ($62,400–130,000) when compared with no screening.
Results of Sensitivity Analysis
Results are sensitive to the relative risk reduction associated with non-participation and the cost of initial screening.
Limitations
Effectiveness data is derived from one major European study. Patterns of sudden death etiology may vary among countries.
Conclusions
Screening young athletes with a 12-lead electrocardiogram plus cardiovascular-focused history and physical may be cost effective.
doi:10.1059/0003-4819-152-5-201003020-00005
PMCID: PMC2873148  PMID: 20194233
10.  A Gender-Based Analysis of High School Athletes Using Computerized Electrocardiogram Measurements 
PLoS ONE  2013;8(1):e53365.
Background
The addition of the ECG to the preparticipation examination (PPE) of high school athletes has been a topic for debate. Defining the difference between the high school male and female ECG is crucial to help initiate its implementation in the High School PPE. Establishing the different parameters set for the male and female ECG would help to reduce false positives. We examined the effect of gender on the high school athlete ECG by obtaining and analyzing ECG measurements of high school athletes from Henry M. Gunn High School.
Methods
In 2011 and 2012, computerized Electrocardiograms were recorded and analyzed on 181 athletes (52.5% male; mean age 16.1±1.1 years) who participated in 17 different sports. ECG statistics included intervals and durations in all 3 axes (X, Y, Z) to calculate 12 lead voltage sums, QRS Amplitude, QT interval, QRS Duration, and the sum of the R wave in V5 and the S Wave in V2 (RS Sum).
Results
By computer analysis, we demonstrated that male athletes had significantly greater QRS duration, Q-wave duration, and T wave amplitude. (P<0.05). By contrast, female athletes had a significantly greater QTc interval. (P<0.05).
Conclusion
The differences in ECG measurements in high school athletes are strongly associated with gender. However, body size does not correlate with the aforementioned ECG measurements. Our tables of the gender-specific parameters can help facilitate the development of a more large scale and in-depth ECG analysis for screening high school athletes in the future.
doi:10.1371/journal.pone.0053365
PMCID: PMC3534687  PMID: 23301064
11.  Left Ventricle Fibrosis Associated With Nonsustained Ventricular Tachycardia in an Elite Athlete: Is Exercise Responsible? A Case Report 
Journal of Athletic Training  2012;47(2):224-227.
Objective:
To emphasize the potentially harmful effects of high-intensity exercise on cardiac health and the fine line between physiologic and pathologic adaptation to chronic exercise in the elite athlete. This case also highlights the crucial need for regular evaluation of symptoms that suggest cardiac abnormality in athletes.
Background:
Sudden cardiac death (SCD) of young athletes is always a tragedy because they epitomize health. However, chronic, high-intensity exercise sometimes has harmful effects on cardiac health, and pathologic changes, such as myocardial fibrosis, have been observed in endurance athletes. In this case, a highly trained 30-year-old cyclist reported brief palpitations followed by presyncope feeling while exercising. Immediate investigations revealed nonsustained ventricular tachycardia originating from the left ventricle on a stress test associated with myocardial fibrosis of the left ventricle as shown with magnetic resonance imaging. Despite complete cessation of exercise, life-threatening arrhythmia and fibrosis persisted, leading to complete restriction from competition.
Differential Diagnosis:
Hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, myocarditis, postmyocarditis, use of drugs and toxic agents, doping, and systemic disease.
Treatment:
The arrhythmia could not be treated with catheter ablation procedure or drug suppression. Therefore, the athlete was instructed to withdraw completely from sport participation and to have a medical follow-up twice each year.
Uniqueness:
To our knowledge, no other report of left ventricle exercise-induced fibrosis associated with life-threatening arrhythmia in a living young elite athlete exists. Only postmortem evidence supports such myocardial pathologic adaptation to exercise.
Conclusions:
To prevent SCD in young athletes, careful attention must be paid to exercise-related symptoms that suggest a cardiac abnormality because they more often are linked to life-threatening cardiovascular disease.
PMCID: PMC3418136  PMID: 22488290
myocardial fibrosis; high-intensity exercise; sudden death
12.  Unrecognized Non-Q-Wave Myocardial Infarction: Prevalence and Prognostic Significance in Patients with Suspected Coronary Disease 
PLoS Medicine  2009;6(4):e1000057.
Using delayed-enhancement cardiovascular magnetic resonance, Han Kim and colleagues show that in patients with suspected coronary disease the prevalence of unrecognized myocardial infarction without Q-waves is more than 3-fold higher than that with Q-waves and predicts subsequent mortality.
Background
Unrecognized myocardial infarction (UMI) is known to constitute a substantial portion of potentially lethal coronary heart disease. However, the diagnosis of UMI is based on the appearance of incidental Q-waves on 12-lead electrocardiography. Thus, the syndrome of non-Q-wave UMI has not been investigated. Delayed-enhancement cardiovascular magnetic resonance (DE-CMR) can identify MI, even when small, subendocardial, or without associated Q-waves. The aim of this study was to investigate the prevalence and prognosis associated with non-Q-wave UMI identified by DE-CMR.
Methods and Findings
We conducted a prospective study of 185 patients with suspected coronary disease and without history of clinical myocardial infarction who were scheduled for invasive coronary angiography. Q-wave UMI was determined by electrocardiography (Minnesota Code). Non-Q-wave UMI was identified by DE-CMR in the absence of electrocardiographic Q-waves. Patients were followed to determine the prognostic significance of non-Q-wave UMI. The primary endpoint was all-cause mortality. The prevalence of non-Q-wave UMI was 27% (50/185), compared with 8% (15/185) for Q-wave UMI. Patients with non-Q-wave UMI were older, were more likely to have diabetes, and had higher Framingham risk than those without MI, but were similar to those with Q-wave UMI. Infarct size in non-Q-wave UMI was modest (8%±7% of left ventricular mass), and left ventricular ejection fraction (LVEF) by cine-CMR was usually preserved (52%±18%). The prevalence of non-Q-wave UMI increased with the extent and severity of coronary disease on angiography (p<0.0001 for both). Over 2.2 y (interquartile range 1.8–2.7), 16 deaths occurred: 13 in non-Q-wave UMI patients (26%), one in Q-wave UMI (7%), and two in patients without MI (2%). Multivariable analysis including New York Heart Association class and LVEF demonstrated that non-Q-wave UMI was an independent predictor of all-cause mortality (hazard ratio [HR] 11.4, 95% confidence interval [CI] 2.5–51.1) and cardiac mortality (HR 17.4, 95% CI 2.2–137.4).
Conclusions
In patients with suspected coronary disease, the prevalence of non-Q-wave UMI is more than 3-fold higher than Q-wave UMI. The presence of non-Q-wave UMI predicts subsequent mortality, and is incremental to LVEF.
Trial Registration
Clinicaltrials.gov NCT00493168
Editors' Summary
Background
Coronary artery disease (CAD; also called coronary heart disease) is the leading cause of death among adults in developed countries. In the USA alone, it kills nearly half a million people every year. CAD is caused by narrowing of the coronary arteries, the blood vessels that supply the heart with oxygen and nutrients. With age, fatty deposits (atherosclerotic plaques) coat the walls of these arteries and restrict the heart's blood supply, which causes the characteristic symptoms of CAD—angina (chest pains that are usually relieved by rest) and shortness of breath. In addition, if a plaque breaks off the wall of a coronary artery, it can completely block that artery and kill part of the heart, which causes a potentially fatal heart attack (doctors call this a myocardial infarction or MI). Heart attacks are often characterized by long-lasting chest pain that is not relieved by rest. Risk factors for CAD include smoking, high blood pressure, high blood levels of cholesterol (a type of fat), and being overweight. Treatments for the condition include lifestyle changes (for example, losing weight), and medications that lower blood pressure and blood cholesterol. The narrowed arteries can also be widened using a device called a stent or surgically bypassed.
Why Was This Study Done?
Not everyone who has a heart attack has chest pain. In fact, some studies suggest that 40–60% of MIs have no obvious symptoms. It is important, however, that these “unrecognized” MIs (UMIs) are diagnosed because they have death rates similar to those of MIs with clinical symptoms and need to be treated in a similar way. Traditionally, UMIs have been diagnosed using an electrocardiogram (ECG). When the heart beats, it generates small electric waves that can be picked up by electrodes attached to the skin. The pattern of these waves (the ECG) provides information about the heart's health. Alterations in the ECG, leading to so-called Q-waves, indicate that a UMI has occurred some time previously. However, not all UMIs result in Q-waves. In this study, the researchers use a recently developed technique—delayed enhancement cardiovascular magnetic resonance (DE-CMR), which can detect heart damage even in patients whose Q-waves are absent—to measure the prevalence (the fraction of a population that has a disorder) of non-Q-wave UMI. The researchers also investigate whether non-Q-wave UMI increases the risk of death.
What Did the Researchers Do and Find?
The researchers used electrocardiography and DE-CMR to look for Q-wave and non-Q-wave UMI, respectively, in 185 patients with suspected CAD but no history of MI. They then followed the patients for 2 years to discover whether a diagnosis of non-Q-wave UMI predicted their likelihood of dying from any cause or from a heart problem. 27% of the patients had evidence of non-Q-wave UMI whereas only 8% had evidence of Q-wave UMI. Patients with non-Q-wave UMI tended to have only a small area of heart damage and, consistent with this limited damage, their hearts pumped near-normal volumes of blood. Examination of the patients' arteries with a technique called coronary angiography indicated that the patients with widespread and/or severe CAD had a higher prevalence of non-Q-wave UMI than those with limited CAD. Finally, patients with non-Q-wave UMI had an 11-fold higher risk of death from any cause and a 17-fold higher risk of death from a heart problem than patients without UMI.
What Do These Findings Mean?
These findings indicate that non-Q-wave UMI occurs more than 3-times as often in patients with suspected CAD than Q-wave UMI and that patients with non-Q-wave UMI have a much greater risk of dying than patients without MI. Thus, if all cases of UMI—both Q-wave and non-Q-wave UMI—could be identified, it might be possible to reduce the number of deaths among people with CAD. However, before any recommendations are made to include DE-CMR in the routine examination of people with suspected CAD to achieve this aim, additional studies must be undertaken to confirm that non-Q-wave UMI is a common feature of CAD and to test whether the early diagnosis of non-Q-wave UMI does extend the life expectancy of people with CAD.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000057.
This study is further discussed in a PLoS Medicine Perspective by Clara Chow
The MedlinePlus encyclopedia has pages on coronary heart disease, heart attacks, and electrocardiograms (in English and Spanish). MedlinePlus also provides links to further information on all aspects of heart disease (in English and Spanish)
Information is available from the US National Heart Lung and Blood Institute on coronary heart disease
The UK National Health Service Choices website also provides information about coronary heart disease (in several languages).
The Nobel Foundation provides an interactive electrocardiogram game
doi:10.1371/journal.pmed.1000057
PMCID: PMC2661255  PMID: 19381280
13.  Feasibility of precompetition medical assessment at FIFA World Cups for female youth players 
British Journal of Sports Medicine  2011;46(16):1132-1133.
Background
Although most experts agree that preparticipation screening is important to prevent sudden cardiac death in sport, only a few reports have been published on the feasibility of its practical implementation.
Methods
The football associations participating in the U-17 and U-20 Women's World Cups 2010 were asked to perform a standardised precompetition medical assessment (PCMA) of their players (in total 672).
Results
Compliance with the requirement for performing the PCMA was high among all teams, particularly from African, Asian and Central/South American countries. No relevant abnormal findings in personal history and clinical cardiological examination were reported. Athletic ECG patterns were frequent, but very few findings were considered to require further investigation. All players were declared as eligible to play.
Conclusions
Based on the demonstrated feasibility of performing a comprehensive PCMA in elite female youth players, the Fédération Internationale de Football Association (FIFA) Executive Committee decided to make the PCMA a compulsory requirement for all FIFA competitions.
doi:10.1136/bjsports-2011-090374
PMCID: PMC3596861  PMID: 22021353
14.  Rate of cardiac arrhythmias and silent brain lesions in experienced marathon runners: rationale, design and baseline data of the Berlin Beat of Running study 
Background
Regular exercise is beneficial for cardiovascular health but a recent meta-analysis indicated a relationship between extensive endurance sport and a higher risk of atrial fibrillation, an independent risk factor for stroke. However, data on the frequency of cardiac arrhythmias or (clinically silent) brain lesions during and after marathon running are missing.
Methods/ Design
In the prospective observational “Berlin Beat of Running” study experienced endurance athletes underwent clinical examination (CE), 3 Tesla brain magnetic resonance imaging (MRI), carotid ultrasound imaging (CUI) and serial blood sampling (BS) within 2-3 days prior (CE, MRI, CUI, BS), directly after (CE, BS) and within 2 days after (CE, MRI, BS) the 38th BMW BERLIN-MARATHON 2011. All participants wore a portable electrocardiogram (ECG)-recorder throughout the 4 to 5 days baseline study period. Participants with pathological MRI findings after the marathon, troponin elevations or detected cardiac arrhythmias will be asked to undergo cardiac MRI to rule out structural abnormalities. A follow-up is scheduled after one year.
Results
Here we report the baseline data of the enrolled 110 athletes aged 36-61 years. Their mean age was 48.8 ± 6.0 years, 24.5% were female, 8.2% had hypertension and 2.7% had hyperlipidaemia. Participants have attended a mean of 7.5 ± 6.6 marathon races within the last 5 years and a mean of 16 ± 36 marathon races in total. Their weekly running distance prior to the 38th BMW BERLIN-MARATHON was 65 ± 17 km. Finally, 108 (98.2%) Berlin Beat-Study participants successfully completed the 38th BMW BERLIN-MARATHON 2011.
Discussion
Findings from the “Berlin Beats of Running” study will help to balance the benefits and risks of extensive endurance sport. ECG-recording during the marathon might contribute to identify athletes at risk for cardiovascular events. MRI results will give new insights into the link between physical stress and brain damage.
Trial registration
clinicaltrials.gov NCT01428778
doi:10.1186/1471-2261-12-69
PMCID: PMC3458995  PMID: 22938148
Marathon running; ECG-recording; Magnetic resonance imaging; Blood sampling; Cardiac arrhythmia
15.  The electrocardiographic abnormalities in highly trained athletes compared to the genetic study related to causes of unexpected sudden cardiac death 
Journal of Medicine and Life  2009;2(4):361-372.
Background: Electrocardiograms in elite endurance athletes sometimes show bizarre patterns suggestive of inherited channelopathies (Brugada syndrome, long QTc, catecholaminergic polymorphic ventricular tachycardia) and cardiomyopathies (arrhythmogenic right ventricular cardiomyopathy, hypertrophic cardiomyopathy) responsible for unexpected sudden cardiac death. Among other methods, genetic analyses are required for correct diagnosis.
Objective: To correlate 12– lead electrocardiographic patterns suggestive of inherited channelopathies and cardiomyopathies to specific genetic analyses.
Design: Prospective study (2004–2007) of screening 12–lead ECG tracings in standard position and higher intercostal spaces V1 to V3 precordial leads, performed in athletes and normal sedentary subjects aged match. Genetic analyses of subjects with ECG abnormalities suggested inherited channelopathies and cardiomyopathies.
Setting: All cardiologic exams and electrocardiograms were performed at ‘Prof. Dr. C.C. Iliescu’ National Institute of Cardiovascular Diseases (Bucharest, Romania). The genetic studies were done at ‘Mina Minovici’ National Institute of Forensic Medicine (Bucharest, Romania).
Participants: 347 elite endurance athletes (seniors–190, juniors–157), mean age of 20; 200 subjects mean age of 21, belonging to the control group of 505 normal sedentary population.
Results: Seniors. RSR' (V1 to V3) pattern, in 45 cases (23.68%), 5 of them with questionable Brugada sign (elevated J wave and ‘coved’ ST segment,< 2mm in one lead, V1. Typically, Brugada 1 sign was found in one case (0.52%) with no SCN5A abnormalities. One athlete (0.52%) had normal ECG and exon1 SCN5A duplication. MRI confirmed three arrhythmic right ventricular cardiomypathy epsilon waves (1.57%), in one case. ST–segment elevation myocardial injury like in V1–V3 precordial leads in 34 athletes (17.89%).Genetic analyses–no gene mutations.
Juniors Upright J wave was found in 43 cases (27.38%). Convex ST segment elevation in V1–V3/V4, in 39 cases (24.84%). Bifid T wave with two distinct peaks was found in 39 cases (24.84%), 5 of them with mild prolonged QTc (0.48 ‘–0.56’) and KCN genes mutations. Nine (5.73%) of the elevated ST segment juniors had questionable Brugada sign, two of which with KCN (n=1) and SCN5A (n=1) gene mutations. Ajmaline provocative test was negative in 4 and was refused by 5 subjects.
Conclusion: Bizarre QRS, ST–T patterns suggestive of abnormal impulse conduction in the right ventricle, including the right outflow tract, associated with prolonged QTc interval in some cases were observed in highly trained endurance athletes. The genetic analyses, negative in most athletes, identified surprising mutations in SCN5A and KCN genes in some cases.
PMCID: PMC3019018  PMID: 20108749
endurance athlete; electrocardiography; genetic analysis
16.  Electrocardiograms of Adult Outpatients Followed-Up in Basic Health Care Units in the Community of the South Region of São Paulo City 
The Permanente Journal  2014;18(2):10-13.
Objective:
The electrocardiogram (ECG) is an important, available, and inexpensive diagnostic tool to assess cardiac symptoms. Few studies address the prevalence of ECG abnormalities or changes of a normal tracing in ECG in outpatients. Our objective was to evaluate ECGs of adult outpatients to determine whether changes from a normal tracing could disclose the patients’ cardiovascular health status.
Methods:
We evaluated all elective ECGs obtained in adult outpatients, from January 2009 to January 2010, at a municipal hospital in the city of São Paulo, Brazil. Electrocardiography was performed with a 3-channel, 12-lead machine (Dixtal Cardio-page EP-3, Dixtal Biomedica, São Paulo, Brazil), and results were interpreted by a cardiologist.
Results:
Electrocardiography was performed in 3567 adult outpatients, 62.5% of whom were women, with a mean age of 51 years (standard deviation [SD] = 16 years). Of the 1918 patients whose ECGs showed abnormalities (mean age = 56 years, SD = 15 years), 1137 were women. Electrocardiographic changes were found in 1184 of the patients. Minor changes were found in 38.3% of patients. A total of 3133 changes were found in 1918 abnormal ECG results. There was a statistical difference related to sex and age, and abnormal ECG results were more frequent in men. There was a high prevalence of abnormal ECG results in the population studied.
Conclusions:
There were more ECGs obtained from women; however, men and elderly patients more frequently had abnormal ECG results.
doi:10.7812/TPP/13-060
PMCID: PMC4022551  PMID: 24694315
17.  Prevalence and Prognostic Significance of ECG Abnormalities in HIV-infected Patients: Results from the Strategies for Management of Antiretroviral Therapy (SMART) Study 
Journal of electrocardiology  2010;44(6):779-785.
Background
It remains debated whether to include resting electrocardiogram (ECG) in the routine care of patients infected with Human immunodeficiency virus (HIV). This is largely because data are limited regarding the prevalence and prognostic significance of ECG abnormalities in HIV-infected patients.
Methods
This analysis included 4518 HIV-infected patients (28% females and 29% blacks) from The Strategies for Management of Antiretroviral Therapy (SMART) study, a clinical trial aimed to compare two HIV treatment strategies. ECG abnormalities were classified using the Minnesota Code. Multivariable adjusted Cox proportional hazards analysis was used to examine the association between baseline ECG abnormalities and incident cardiovascular disease.
Results
More than half of the participants (N=2325, 51.5%) had either minor or major ECG abnormalities. Minor ECG abnormalities (48.6%) were more common than major ECG abnormalities (7.7%). During a median follow-up of 28.7 months, 155 (3.4%) participants developed incident cardiovascular disease. After adjusting for the study treatment arms, the presence of major, minor, and either minor or major ECG abnormalities were significantly predictive of incident cardiovascular disease [Hazard ratio (95% Confidence Interval): 2.76 (1.74, 4.39), p<0.001; 1.58 (1.14, 2.20), p=0.006; 1.57 (1.14, 2.18), p=0.006, respectively]. However, after adjusting for demographics, common cardiovascular risk factors and HIV characteristics (full model), presence of major ECG abnormalities was still significantly predictive of cardiovascular disease [1.83 (1.12, 2.97), p=0.015)], but not minor or minor or major abnormalities taken together [1.26 (0.89, 1.79), p=0.18; 1.25 (0.89, 1.76), p=0.20, respectively]. Individual ECG abnormalities that significantly predicted cardiovascular disease in the fully adjusted model included major isolated ST/T abnormalities, major prolongation of QT interval, minor isolated ST/T and minor isolated Q/QS abnormalities.
Conclusion
Nearly one in two of the HIV-infected patients in SMART study had ECG abnormalities; one in thirteen had major ECG abnormalities. Presence of ECG abnormalities, especially major ECG abnormalities was independently predictive of incident cardiovascular disease. These results suggest that the ECG could provide a convenient risk screening tool in HIV-infected patients.
doi:10.1016/j.jelectrocard.2010.10.027
PMCID: PMC3060290  PMID: 21145066
HIV/AIDS; ECG; Cardiovascular Disease; SMART Study
18.  Significance of deep T-wave inversions in asymptomatic athletes with normal cardiovascular examinations: practical solutions for managing the diagnostic conundrum 
British Journal of Sports Medicine  2012;46(Suppl_1):i51-i58.
Preparticipation screening programmes for underlying cardiac pathologies are now commonplace for many international sporting organisations. However, providing medical clearance for an asymptomatic athlete without a family history of sudden cardiac death (SCD) is especially challenging when the athlete demonstrates particularly abnormal repolarisation patterns, highly suggestive of an inherited cardiomyopathy or channelopathy. Deep T-wave inversions of ≥2 contiguous anterior or lateral leads (but not aVR, and III) are of major concern for sports cardiologists who advise referring team physicians, as these ECG alterations are a recognised manifestation of hypertrophic cardiomyopathy (HCM) and arrhythmogenic right ventricular cardiomyopathy (ARVC). Subsequently, inverted T-waves may represent the first and only sign of an inherited heart muscle disease, in the absence of any other features and before structural changes in the heart can be detected. However, to date, there remains little evidence that deep T-wave inversions are always pathognomonic of either a cardiomyopathy or an ion channel disorder in an asymptomatic athlete following long-term follow-up.
This paper aims to provide a systematic review of the prevalence of T-wave inversion in athletes and examine T-wave inversion and its relationship to structural heart disease, notably HCM and ARVC with a view to identify young athletes at risk of SCD during sport. Finally, the review proposes clinical management pathways (including genetic testing) for asymptomatic athletes demonstrating significant T-wave inversion with structurally normal hearts.
doi:10.1136/bjsports-2011-090838
PMCID: PMC3603779  PMID: 23097480
19.  Syncope due to Brugada syndrome in a young athlete 
A 30‐year‐old male athlete with exercise‐related syncopal symptoms spontaneously exhibited a type 1 Brugada ECG and was inducible during electrophysiology study. He was diagnosed with symptomatic Brugada syndrome and deemed at high risk of sudden cardiac death. Thus, he received a cardioverter/defibrillator and was advised to abstain from further competitive sports activities. This case points to a role of the ECG in pre‐participation screening. It also demonstrates that, in athletes with Brugada syndrome, repolarisation anomalies may be markedly attenuated during vigorous exercise and considerably increased immediately after exercise. The observed J‐wave amplitude dynamics suggests enhancement of pre‐existing autonomic dysfunction through heavy exertion.
doi:10.1136/bjsm.2006.030098
PMCID: PMC2465223  PMID: 17138637
20.  Early continuous ST segment monitoring in unstable angina: prognostic value additional to the clinical characteristics and the admission electrocardiogram. 
Heart  1996;75(3):222-228.
BACKGROUND AND OBJECTIVE: In unstable angina, clinical characteristics, resting electrocardiography, and early continuous ST segment monitoring have been individually reported to identify subgroups at increased risk of adverse outcome. It is not known, however, whether continuous ST monitoring provides additional prognostic information in such a setting. DESIGN: Observational study of 212 patients with unstable angina without evidence of acute myocardial infarction admitted to district general hospitals, who had participated in a randomised study comparing heparin and aspirin treatment versus aspirin alone. METHODS: Clinical variables and a 12 lead electrocardiogram (ECG) were recorded at admission, and treatment was standardised to include aspirin, atenolol, diltiazem, and intravenous glyceryl trinitrate, in addition to intravenous heparin (randomised treatment). Continuous ST segment monitoring was performed for 48 h and all inhospital adverse events were recorded. RESULTS: The admission ECG was normal in 61 patients (29%), showed ST depression in 59 (28%) (17 > or = 0.1 mV), and T wave changes in a further 69 (33%). The remaining 23 had Q waves (18), right bundle branch block (four), or ST elevation (one). During 8963 h of continuous ST segment monitoring (mean 42.3 h/patient), 132 episodes of transient myocardial ischaemia (104 silent) were recorded in 32 patients (15%). Forty patients (19%) had an adverse event (cardiac deaths (n = 3), non-fatal myocardial infarction (n = 6) and, emergency revascularisation (n = 31)). Both admission ECG ST depression (P = 0.02), and transient ischaemia (P < 0.001) predicted an increased risk of non-fatal myocardial infarction or death, while no patients with a normal ECG died or had a myocardial infarction. Adverse outcome was predicted by admission ECG ST depression (regardless of severity) (odds ratio (OR) 3.41) (P < 0.001), and maintenance beta blocker treatment (OR 2.95) (P < 0.01). A normal ECG predicted a favourable outcome (OR 0.38) (P = 0.04), while T wave or other ECG changes were not predictive of outcome. Transient ischaemia was the strongest predictor of adverse prognosis (OR 4.61) (P < 0.001), retaining independent predictive value in multivariate analysis (OR 2.94) (P = 0.03), as did maintenance beta blocker treatment (OR 2.85) (P = 0.01) and admission ECG ST depression, which showed a trend towards independent predictive value (OR 2.11) (P = 0.076). CONCLUSIONS: Patients with unstable angina and a normal admission ECG have a good prognosis, while ST segment depression predicts an adverse outcome. Transient myocardial ischaemia detected by continuous ST segment monitoring in such patients receiving optimal medical treatment provides prognostic information additional to that gleaned from the clinical characteristics or the admission ECG.
PMCID: PMC484276  PMID: 8800982
21.  Safety of Monitoring Exercise for Early Hospital-based Cardiac Rehabilitation 
Annals of Rehabilitation Medicine  2012;36(2):262-267.
Objective
To survey the cardiovascular complications induced by cardiac monitoring exercise during 10 years of our cardiac rehabilitation (CR) clinic and report on the safety of monitoring exercise training for early hospital-based CR.
Method
All cardiac patients who participated in our exercise program from January 2000 through December 2009 were recruited as study subjects. We stratified the exercise risks of cardiac events and conducted the monitoring exercise with individualized prescriptions. We measured all cardiac complications, including death, symptoms, abnormal hemodynamic responses, and electrocardiogram (ECG) abnormality during exercise training, for 10 years. A total of 975 patients (68% male; mean age, 58.9±10.6) were included in this study. Initial indications for CR were recent percutaneous transluminal coronary angioplasty (PTCA) (75%), post-cardiac surgery (coronary bypass graft, 13.2%), valvular surgery and other cardiac surgery (4.2%), and others (7.6%).
Results
The study population underwent 13,934 patient-hours of monitoring exercise. No death, cardiac arrest or acute myocardial infarction (AMI) occurred during exercise (0/13,934 exercise-hours). Fifty-nine patients experienced 70 cardiovascular events during the 13,934 exercise-hours (1/199 exercise-hours); there were 17 cases of angina only (1/820 exercise-hours), 31 cases of ECG abnormalities only (1/449 exercise-hours), 12 cases of angina with ECG abnormalities (1/1,161 exercise-hours), and 10 cases of abnormal hemodynamic responses (1/1,393 exercise-hours).
Conclusion
Early hospital-based CR is safe enough that no death, cardiac arrest or AMI occurred during the 13,934 patient-hours of monitoring exercise. However, risk stratification for exercise-induced cardiovascular events, proper exercise prescriptions, and intensive ECG monitoring are required prior to initiation of the monitoring exercise.
doi:10.5535/arm.2012.36.2.262
PMCID: PMC3358684  PMID: 22639752
Cardiovascular disease; Exercise; Myocardial infarction; Rehabilitation
22.  Increased Short-Term Variability of the QT Interval in Professional Soccer Players: Possible Implications for Arrhythmia Prediction 
PLoS ONE  2011;6(4):e18751.
Background
Sudden cardiac death in competitive athletes is rare but it is significantly more frequent than in the normal population. The exact cause is seldom established and is mostly attributed to ventricular fibrillation. Myocardial hypertrophy and slow heart rate, both characteristic changes in top athletes in response to physical conditioning, could be associated with increased propensity for ventricular arrhythmias. We investigated conventional ECG parameters and temporal short-term beat-to-beat variability of repolarization (STVQT), a presumptive novel parameter for arrhythmia prediction, in professional soccer players.
Methods
Five-minute 12-lead electrocardiograms were recorded from professional soccer players (n = 76, all males, age 22.0±0.61 years) and age-matched healthy volunteers who do not participate in competitive sports (n = 76, all males, age 22.0±0.54 years). The ECGs were digitized and evaluated off-line. The temporal instability of beat-to-beat heart rate and repolarization were characterized by the calculation of short-term variability of the RR and QT intervals.
Results
Heart rate was significantly lower in professional soccer players at rest (61±1.2 vs. 72±1.5/min in controls). The QT interval was prolonged in players at rest (419±3.1 vs. 390±3.6 in controls, p<0.001). QTc was significantly longer in players compared to controls calculated with Fridericia and Hodges correction formulas. Importantly, STVQT was significantly higher in players both at rest and immediately after the game compared to controls (4.8±0.14 and 4.3±0.14 vs. 3.5±0.10 ms, both p<0.001, respectively).
Conclusions
STVQT is significantly higher in professional soccer players compared to age-matched controls, however, further studies are needed to relate this finding to increased arrhythmia propensity in this population.
doi:10.1371/journal.pone.0018751
PMCID: PMC3078143  PMID: 21526208
23.  Gender Differences in the Prevalence of Electrocardiogram Abnormalities in the Elderly: A Population Survey in India 
Background: The health transition in India reflects the growing burden of cardiovascular diseases. It is well-known that there are significant and meaningful differences in the measured electrocardiogram (ECG) parameters between females and males. Specific to ECG diagnosis and ischemia, reports have indicated a higher number of false positive results in female patients than in male patients. This study was aimed at examining gender difference in the prevalence of ECG abnormality in older people who were free of coronary heart disease (CHD) and its associated risk factors.
Methods: This study was conducted in Solapur city using 400 apparently healthy asymptomatic subjects with an age range of 45 to 74 years. A resting 12-lead ECG was recorded in supine position in accordance with classical recommendations. The various ECG abnormalities were defined according to Minnesota code. The findings were analyzed using Chi Square test at P<0.05.
Results: Out of 400 ECGs recorded, 152 showed abnormalities. The prevalence of ECG abnormalities was significantly (P<0.001) more in males than in females. Major prevalence of ECG abnormalities in males observed were LAD, LVH, sinus bradycardia, LBBB and Q/QS patterns. There was no significant gender difference in the prevalence of other ECG abnormalities.
Conclusion: This study has outlined the overall prevalence of ECG abnormalities in males as well as in females in Solapur city. We found highly significant (P<0.001) increase in the prevalence of ECG abnormalities in males as compare to females.
PMCID: PMC3470073  PMID: 23115437
Electrocardiography; gender differences; healthy subjects
24.  Incremental prognostic value of the exercise electrocardiogram in the initial assessment of patients with suspected angina: cohort study 
Objective To determine whether resting and exercise electrocardiograms (ECGs) provide prognostic value that is incremental to that obtained from the clinical history in ambulatory patients with suspected angina attending chest pain clinics.
Design Multicentre cohort study.
Setting Rapid access chest pain clinics of six hospitals in England.
Participants 8176 consecutive patients with suspected angina and no previous diagnosis of coronary artery disease, all of whom had a resting ECG recorded. 4848 patients with a summary exercise ECG result recorded (positive, negative, equivocal for ischaemia) comprised the summary ECG subset of whom 1422 with more detailed exercise ECG data recorded comprised the detailed ECG subset.
Main outcome measure Composite of death due to coronary heart disease or non-fatal acute coronary syndrome during median follow-up of 2.46 years.
Results Receiver operating characteristics curves for the basic clinical assessment model alone and with the results of resting ECGs were superimposed with little difference in the C statistic. With the exercise ECGs the C statistic in the summary ECG subset increased from 0.70 (95% confidence interval 0.68 to 0.73) to 0.74 (0.71 to 0.76) and in the detailed ECG subset from 0.74 (0.70 to 0.79) to 0.78 (0.74 to 0.82). However, risk stratified cumulative probabilities of the primary end point at one year and six years for all three prognostic indices (clinical assessment only; clinical assessment plus resting ECG; clinical assessment plus resting ECG plus exercise ECG) showed only small differences at all time points and at all levels of risk.
Conclusion In ambulatory patients with suspected angina, basic clinical assessment encompasses nearly all the prognostic value of resting ECGs and most of the prognostic value of exercise ECGs. The limited incremental value of these widely applied tests emphasises the need for more effective methods of risk stratification in this group of patients.
doi:10.1136/bmj.a2240
PMCID: PMC2583389  PMID: 19008264
25.  Maximal Exercise Electrocardiography Responses and Coronary Heart Disease Mortality Among Men With Diabetes Mellitus 
Circulation  2008;117(21):2734-2742.
Background
An abnormal ECG during maximal exercise testing has been shown to be a powerful predictor of future coronary heart disease (CHD) mortality in asymptomatic men. However, little is known about the relationship between exercise ECG responses and CHD risk in men with diabetes mellitus.
Methods and Results
We examined the association between exercise ECG responses and mortality in 2854 men with documented diabetes mellitus (mean age 49.5 years) who completed a maximal treadmill exercise test during the period from 1974 to 2001 and who were without a previous cardiovascular disease (CVD) event at baseline. Mortality due to all causes, CHD, and CVD were the main outcome measures across categories of exercise ECG responses, with stratification by cardiorespiratory fitness, quantified as treadmill test duration. During an average follow-up of 16 years, 441 deaths (210 CVD and 133 CHD) were identified. Across normal, equivocal, and abnormal exercise ECG groups, age- and examination year-adjusted CHD mortality rates per 10 000 person-years were 23.0, 48.6, and 69.0, respectively (Ptrend<0.001). After further adjustment for fasting plasma glucose level, smoking, body mass index, hypercholesterolemia, hypertension, family history of CVD or diabetes mellitus, abnormal resting ECG responses, and cardiorespiratory fitness, hazard ratios (95% confidence intervals) were 1.00 (referent), 1.68 (1.01 to 2.77), and 2.21 (1.41 to 3.46; Ptrend<0.001). Similar patterns of associations were noted between exercise ECG testing and both CVD and all-cause mortality risk.
Conclusions
Among men with diabetes mellitus, equivocal and abnormal exercise ECG responses were associated with higher risk of all-cause, CVD, and CHD mortality.
doi:10.1161/CIRCULATIONAHA.107.729277
PMCID: PMC2875671  PMID: 18490521
exercise; electrocardiography; coronary disease; diabetes mellitus

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