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Glenn C. Terry, MD contributed to conception and design; acquisition and analysis and interpretation of data; and drafting, critical revision, and final approval of the article. James M. Kyle, MD, FACSM; James M. Ellis, Jr, MD, FACEP; John Cantwell, MD; Ron Courson, ATC, PT; and Ron Medlin, ATC, contributed to conception and design; acquisition and analysis and interpretation of the data; and critical revision and final approval of the article.
To emphasize the importance of decreasing the response time by a trained target responder to increase the survival rate among athletes experiencing sudden cardiac arrest at an athletic event.
Death due to sudden cardiac arrest that is witnessed is preventable in many cases. However, most people who experience this condition die because of a prolonged response time from onset of the fatal arrhythmia to defibrillation by trained treatment providers. If athletic trainers or other members of the athletic care medical team are trained as target responders and equipped with automated electronic defibrillators, they can immediately treat an athlete who experiences a sudden, life-threatening tachyarrhythmia. This prompt response to the life-threatening emergency should result in a higher survival rate.
We review the causes of sudden cardiac arrest during athletic events, note some unusual clinical presentations, discuss improved methods of response and new equipment for treatment, and define the athletic trainer's role as a target responder trained to treat people experiencing sudden cardiac arrest at an athletic event.
An athletic care team willing to become part of an emergency response team can help improve the survival rate of athletes experiencing sudden cardiac arrest at an athletic event.
In the United States each year, sudden cardiac arrest kills 350000 people, which is approximately 1000 people per day.1 Before 1990, cities with established advanced and basic life support programs reported that their efforts to resuscitate those people experiencing sudden cardiac arrest resulted in a 4% to 11% survival rate.2 The American Heart Association has challenged cities to improve this survival rate to 30%.1 These statistics are derived from death certificates of people of all age groups who experienced sudden cardiac arrest. The exact incidence of sudden cardiac arrest in athletes is unknown because no universal, standard surveillance method is used.
We do know that death during an athletic event can result from direct and indirect causes.2 The direct causes of death primarily are traumatic (eg, a closed head injury). The major indirect cause of death during athletics is from an arrhythmia resulting in sudden cardiac arrest. From 1931 to 1986, direct causes of death in high school athletes outnumbered indirect causes by a ratio of 2:1.3 Since 1982, that ratio has reversed to 1:2 due to an increase in the indirect causes of death.2 Unfortunately, much of the information on the indirect causes of death has been obtained from newspaper reports.
The American Heart Association4 reviewed 158 cases of death due to sudden cardiac arrest in athletes that primarily were reported in American newspapers from 1985 to 1995. Of these deaths, 138 (68%) occurred in players who had a mean age of 17 years and who participated in either football or basketball. The occurrence of sudden cardiac arrest in 70 whites (52%), 69 African Americans (44%), 8 Asians (2%), 1 Hispanic (0.6%), and 1 Native American (0.6%) demonstrated that it is nondiscriminatory. Although football and basketball were the most common sports, 18 different competitive sports were represented.5 The fact that most of these reports originated in the news media has helped focus public awareness on the problem; however, these reports do not represent the actual incidence of sudden cardiac arrest in athletes because no universally used, standardized surveillance method, which would allow statistical evaluation of these problems at a national level, is required.
The clinical presentation of sudden cardiac arrest in athletes is abrupt, and, unfortunately, the player usually has had no prodrome before the cataclysmic event.6 In the report of Maron et al,4 90% of the 158 athletes experiencing sudden cardiac arrest collapsed during or immediately after a training session or scheduled athletic contest. Only 12 of the 158 athletes reported symptoms before the fatal event. At their preparticipation physical examination, athletes may not report the symptoms that alert medical personnel to their risk of sudden cardiac arrest. Thus, the arrhythmia is usually instantaneous in an asymptomatic athlete and occurs during or at the end of intense physical activity, with death quickly following.7 The first people to respond must be well prepared to reach, evaluate, and treat the athlete before he or she dies.
Our purpose is to review the causes of sudden cardiac arrest during athletic events, to note some unusual clinical presentations, to discuss improved methods of response and new equipment for treatment, and to define the athletic trainer's role as a target responder trained to treat sudden cardiac arrest.
The most common cause of sudden cardiac arrest in athletes younger than 35 years is a consequence of an underlying cardiac abnormality. According to a study by The American Heart Association,4 the cardiac problems that can cause sudden cardiac arrest include hypertrophic cardiomyopathy (36%), hypertrophic cardiomyopathy–like structural changes (10%), anomalous origin of the left main coronary artery (10%), other coronary anomalies (9%), myocarditis (6%), ruptured aortic aneurysm (5%), tunneled left anterior descending artery (5%), aortic valve stenosis (4%), dilated cardiomyopathy (3%), and arrhythmogenic right ventricular dysplasia (2%). Other causes of sudden cardiac arrest include cardiac concussion (commotio cordis),8,9 drug-related (arrhythmia-allowing or arrhythmia-inducing)6 difficulties,1,2 and underlying coronary artery disease causing myocardial infarction with an associated fatal arrhythmia.
Preventing sudden cardiac arrest is difficult if the preexisting cardiac condition is not recognized. To try to achieve this end, physicians should include a thorough history and cardiac examination as part of the preparticipation physical examination. A 12-lead electrocardiogram (ECG), a stress rhythm ECG, or both should be performed if any risk factors are identified at the initial assessment.10 Those risk factors include a history of chest pain, shortness of breath, or arrhythmia; a history of cardiac problems requiring medication; and a family history of death due to sudden cardiac arrest at a young age. Findings on clinical examination of bruits, murmurs, high blood pressure, and arrhythmias deserve more thorough evaluation.
Athletes who have a recognizable or a known preexisting physical condition, such as Marfan syndrome, need to be well screened because Marfan syndrome is associated with heart valve anomalies and aortic aneurysm (which may rupture).4 They also are at risk for sudden cardiac arrest.
Evaluation beyond this baseline may require special testing following a cardiology evaluation and may use a 12-lead ECG stress test. A limited echocardiogram is the best screening test, but a full echocardiogram is required if symptoms and risk factors are identified. It is useful in diagnosing hypertrophic cardiomyopathy, myocarditis, left ventricle dysfunction, valve abnormalities, and dilated aortic root. In addition, electron-beam computed tomography scanning can help the cardiologist diagnose coronary artery anomalies, such as coronary artery aneurysm or left coronary artery origin from the right side, but is not commonly used as a screening test.11,12 This test and coronary artery angiography can demonstrate coronary artery abnormalities; however, they are not cost effective and thus should not be considered “screening” tests.
Because using these special tests to routinely screen large numbers of athletes is not cost effective, these more advanced screening tests usually are limited to athletes with cardiac symptoms or signs determined by history, examination, or ECG rhythm abnormalities. Therefore, the athletic care medical team needs to be well prepared to treat sudden cardiac arrest in athletes when it occurs.
The first unusual clinical presentation is commotio cordis or cardiac concussion.8,9,13 Blunt trauma to the chest can interrupt the electric function of the heart, resulting in ventricular fibrillation. The subsequent electric dysfunction results from the impact being delivered during the diastolic phase of the cardiac cycle (at the peak of the T wave electrically), which affects the repolarization of the heart and creates the fatal arrhythmia.14 This problem can occur in noncontact (eg, baseball) or contact (eg, hockey) sports.9 Since 1995, 60 deaths in children and young adults have been attributed to this cause (B. Maron, unpublished data, July 1999). Awareness of this condition and the development and use of protective padding and softer youth baseballs could aid in preventing the problem.8,9,13,15
The second unusual clinical syndrome is cardiac arrest occurring in combination with a sentinel seizure. The seizure is usually the first symptom that is obvious to a bystander and probably results from oxygen deprivation in the brain because of the fatal arrhythmia. As the athlete collapses due to loss of consciousness, the seizure activity decreases. Prompt cardiac assessment at this time is critical because further delay can result in death from the unrecognized fatal arrhythmia. The incidence of a sentinel seizure in association with sudden cardiac arrest is uncertain. However, through reviewing 10 news media reports of sudden death and contacting athletic department personnel involved in these cases during 1997 and 1998, we determined that seizure activity was cited as the initial clinical presentation in 3 of the 10 patients. To our knowledge, this complex issue of seizure associated with sudden cardiac arrest has not been reported in the literature, but this association should be considered in the future.
The third clinical condition is a fatal arrhythmia related to intense physical activity combined with illegal or legal drug use.6,16 Cocaine is reported to be associated with an increased risk of a myocardial infarction by 24 times in the first hour after taking it.16 Certainly, a fatal arrhythmia can result from the myocardial infarction. Inadequate dosage of legal medications, such as β blockers, can result in arrhythmia and sudden cardiac arrest. The beneficial effect of the medication on the heart's ability to withstand the stress of intense activity can be reduced due to an inadequate level of the drug in the blood.6 This situation was thought to contribute to the cause of Hank Gathers' death while playing basketball.6 With respect to athletes taking legal medications, a medication history, cardiology evaluation, maintenance evaluation, and possibly measurement of blood levels of medication may be required. The team cardiologist should counsel all athletes and their parents regarding the risk of participation in the face of both cardiac conditions and cardiac-affecting medications. A cardiac-monitoring program is usually established for these at-risk athletes.
It would seem that the way to prevent problems with illegal drugs is to include drug screenings as part of the preparticipation evaluation to determine illegal drug use. However, these screenings are not cost effective for any school and, in fact, could financially penalize all schools, especially those with limited financial resources.
Unfortunately, the incidence and survival data for these unusual clinical syndromes are unknown because no single national sentinel data tracking system is used consistently. The universal acceptance of and compliance with such a system might provide data to improve our understanding of these complex issues and their prevention.
The effective treatment of an athlete experiencing sudden cardiac arrest depends on a sequence of responses by well-prepared providers, so that the steps, when linked together, form a “chain of survival” for the successful management of sudden cardiac arrest.1,2 The chain of survival includes the following: (1) prompt emergency medical system (EMS) activation; (2) early cardiopulmonary resuscitation (CPR) by a first or target responder (less than 2 minutes); (3) early defibrillation (2 to 4 minutes); (4) early advanced life support (less than 8 minutes); and (5) late advanced life support.17 The first 4 links must have as short a time delay as possible to significantly increase survival rates.
The first link in the chain of survival begins with summoning EMS directly or through a bystander as a trained target responder begins early intervention of basic life support (BLS). The chance of survival of a person experiencing sudden cardiac arrest is reported to decline by 5% to 10% each minute the condition is left untreated; therefore, the sooner BLS, including defibrillation, is activated, the better the athlete's chance of survival.1,2 The EMS response time in most communities ranges from 12 to 15 minutes.2 This delay has horizontal and vertical components.18 The horizontal delay begins with activation of EMS by telephone (ie, dialing 911 where available) and ends with the arrival of EMS at the site. This time delay is similar for most communities with well-developed EMS programs (eg, 4.5 to 5.5 minutes for New York and 4.9 to 5.6 minutes for Las Vegas).18,19 The vertical time delay begins with the time required to park the rescue vehicle and ends with initiation of the first defibrillation shock. This vertical component seems to affect the total time from EMS activation to defibrillation more than the horizontal component affects it, with the total response time in Las Vegas averaging 9.8 minutes in people who lived (29.3%) and 12.4 minutes in people who died.18 The additional delay of EMS response caused by the vertical component, when not coupled with an aggressive, community-oriented, trained target-responder BLS system with defibrillation capabilities, may be why many large communities, including Chicago and New York, have reported only a 1% to 2% survival rate in people experiencing sudden cardiac arrest.18–21
White et al22 reported on a community in which “target responders,” including EMS personnel and police, were equipped with automated external defibrillators (AEDs). Additionally, the target responder response time was improved to 5.4 minutes. These 2 changes resulted in a 49% survival rate in patients with sudden cardiac arrest. In 58% of the people who lived, police first arrived as the target responder, and in 42% of the people who lived, EMS personnel first arrived as target responders.22 This study demonstrates the success achieved by combining EMS activation with target-responder BLS, including early defibrillation. It also demonstrates that the use of this model in athlete care is promising.
Giving athletic trainers access to an AED as a university-supplied piece of equipment outside the normal budget of the athletic department, providing a university-supported training program that integrates them as target responders for athletic care, and facilitating response drills with local EMS representatives would enhance survival probabilities if such an event occurred during a university-sanctioned athletic practice or competition. Certainly, this coordination between the athletic care emergency plan of the university and that of the community should be motivated by the same endpoint—improving survival in athletes experiencing sudden cardiac arrest.
The second and third links in the chain of survival are inseparable from the first. Early CPR, which is a capability of a first responder trained in BLS, can enable the heart to survive longer when it is in fibrillation.1,17 Larsen et al23 calculated a 5.5% per minute decrease in survival and attributed 2.2% of that decline to each minute of delay in CPR initiation. However, CPR alone cannot reinstitute the normal cardiac output or normal electric activity for a heart in ventricular fibrillation.1,17 The quality of CPR is important; authors of one study24 have suggested that when CPR is administered by bystanders, it is administered effectively less than half the time. However, at best, CPR delivers 60 to 80 mm Hg of pressure to the heart, only generating approximately 30% of the cardiac output.1,17 As a consequence of these factors, the American Heart Association has included early defibrillation training as a necessary addition to CPR in BLS certification.1
Combining the first 2 links with the third link in the chain of survival for treating sudden cardiac arrest (ie, early defibrillation), thus, is deemed necessary. The sooner an athlete in sudden cardiac arrest due to a tachyarrhythmia receives defibrillation, the better his or her chance of survival. More than 95% of patients who receive defibrillation shock in the first minute of arrest survive.2,17 Each minute of delay in initiating defibrillation after an arrest lasting 9.4 minutes leads to a 5% to 10% decrease in a person's survival—even if the person had been receiving CPR during that period.2,17 One theory proposed is that ventricular defibrillation decays to asystole as the heart becomes ischemic.25 Certainly, the early target-responder's quick response, effective CPR, early defibrillation, and a shortened EMS response time are responsible for the improvements in survival rates noted here,2,17,20,22,26 with White et al22 reporting the most significant improvement in survival rate (49%).
In athletic medicine, certainly the early target responder should be the athletic trainer who is well prepared to respond rapidly and is trained in both CPR and early defibrillation.
Two types of defibrillation equipment can be used for this purpose: a manual defibrillator or an AED. A manual defibrillator must be used by a physician or paramedic because it requires an analysis or interpretation of the cardiac rhythm by the skilled responder. When used, the manual defibrillator's specificity is 96% for the appropriate shock to be delivered to treat the arrhythmia. This specificity, however, is dependent on the responder's ability to recognize a shockable arrhythmia.1,2 In addition, the time delay for this treatment application equals the average EMS response time in a given community plus the average 1 minute required for rhythm interpretation.1,2
Unlike manual units, the recently introduced AED, which can be used by a trained target responder,1,2 can automatically analyze the cardiac arrhythmia through an internal diagnostic algorithm and can determine the need for defibrillation. The specificity is 100% for appropriate shock delivery, and the unit may take 1 minute less than a manual defibrillator to use because the responder does not have to evaluate or interpret a rhythm strip.2 This 1-minute difference between manual defibrillation and AED use translates into a 10% improvement in survival rate. In addition, the lithium battery in an AED can be used for years and does not lose its charge between uses—another benefit over a manual defibrillator, which must have its battery repeatedly recharged.2 Finally, the defibrillation of patients by a broader target responder group than EMS personnel alone has been shown to improve survival rates.22 From an accounting basis alone, the cost of a basic LIFEPAK 500 (Medtronic Physio-Control, Redmond, WA) AED is approximately $3000, but the cost of a LIFEPAK 10 defibrillator/monitor/pacemaker is approximately $9000.
The main fact learned from the data obtained from such community efforts is that an improvement in the survivorship of athletes experiencing sudden cardiac arrest is possible if the athletic care program includes prompt response by target responders who are trained in BLS to include defibrillation and who are equipped with AEDs. Target responders should include EMS personnel, police, sheriffs, security guards, medical personnel, athletic trainers, and administrators involved in organizing medical care for sporting and civic events. Certainly, medical “control” is necessary for a cohesive program, but the stimulus for development can come from any interested participant. The “Casino Project” in Las Vegas illustrates appropriate application of these principles. After casino security guards were trained as target responders and the vertical response time of EMS was improved, the survival rate of casino patrons experiencing sudden cardiac arrest improved significantly.18
Not all athletes in sudden cardiac arrest can be treated successfully with electric defibrillation shocks. Because asystole, or flatline ECG activity, indicates that the heart has no electric activity, no mechanical pumping effect is possible.2,17 In addition, the opposite condition of pulseless electric activity (PEA) can occur.25 In this condition, electric activity is present, but the heart muscle does not respond to it; therefore, no mechanical pumping occurs, and no pulse is palpable. In these cases, CPR instead of defibrillation is required to provide some pumping effect, and intravenous access for treatment with epinephrine and bicarbonate should be established. The cause of the PEA must be sought quickly for survival to be ensured. The most common correctable causes of PEA include hypovolemia, cardiac tamponade, tension pneumothorax, hypoxemia, and acidosis.25
The target responder can use BLS, including defibrillation capabilities, to promptly treat the athlete experiencing a ventricular fibrillation and can use CPR to sustain the athlete with PEA until EMS paramedics arrive to provide advanced life support. The incidence of the initial arrhythmia, as well as whether it was witnessed, has much to do with survival.18 Most occurrences of sudden cardiac arrest in athletes are thought to be due to tachyarrhythmia; therefore, they most commonly can be treated with defibrillation.1,2,4,6,8,9 This cause differs from the initial arrhythmia that is reported to cause the condition in an older at-risk group, which includes officials, referees, coaches, and spectators. The fatal arrhythmia in this older patient population most likely parallels the findings of Sedgwick et al,27 who implicated ventricular fibrillation in 64% of patients, ventricular tachycardia in 4%, bradycardia in 28%, and PEA in 4% as the initial arrhythmia.
The fourth link in the chain of survival is early advanced life support. Defibrillation, early intubation techniques, external pacemakers, cardiac medications, and early transport to cardiac care units or to emergency departments equipped and staffed for advanced life support complete this link of survival.1,2 For this fourth component of any athletic care medical program's acute emergency plan to work, EMS personnel, including paramedics with advanced life support capabilities, must be notified when a cardiac arrest is first identified to shorten the horizontal component of time delay. Then, in addition to arriving on site promptly, they must try to shorten the vertical component of their response time delay to assume patient care. The smooth transition of the care of the athlete from the certified athletic trainer as the target responder to the EMS responder depends on the training of both responders. High-quality CPR, as well as defibrillation with an AED, is important also. The leads that the athletic trainer as the target responder uses for the AED must be compatible with EMS equipment, and replacement protocols must be developed. The EMS personnel then assume care of the athlete and begin early advanced life support treatment.
An athletic program's medical staff, including certified athletic trainers and physicians, needs to be involved in target-responder training since that staff becomes a satellite target-responder group in the EMS plans of the university and the community. Although the athletic care medical team may only be responsible for providing the first 3 links in the chain of survival, this group, as well as police, sheriffs, security guards, and any other group designated as target responders, must be integrated into the community's emergency plan and must be trained and recertified as necessary in BLS, AED use, and advanced life support transfers to the community EMS team to significantly improve survival of the affected athlete.
The fifth link in the chain of survival is late advanced life support. This link is provided by the full spectrum of advanced life support care offered through emergency departments and cardiac care units, their staffs, and cardiologists and cardiovascular surgeons. The treatment can include in-dwelling pacemakers or defibrillators, medications, and other surgery. Certainly, this late advanced life support capability is outside the spectrum of care that the athletic care medical team can provide. However, if the athletic care medical team is not well prepared, the athlete experiencing a life-threatening arrhythmia will not survive to take advantage of late advanced life support treatments.
In order for any athletic care medical team to improve its ability to enhance survival of athletes experiencing sudden cardiac arrest, each of these links of survival must be forged, or combined, into a dependable chain for survival—the purpose of any emergency medical plan. Any athletic program's emergency plan thus becomes a vital peripheral link in this chain of survival.
After recognizing the many problems that result in a poor chance of survival for athletes experiencing sudden cardiac arrest, the athletic care medical team should develop a comprehensive and well-integrated plan to address these emergencies. The first, second, third, and fourth components of the emergency plan should proceed with near-simultaneous activation of EMS with a practiced response time (less than 8 minutes to initiation of treatment). This includes planning prompt EMS access to the field of play, which might otherwise be delayed wherever a large concentration of people gathers (eg, a civic event, an athletic stadium, or a sports arena). This EMS response should be combined with a more rapid (less than 2-minute) response by the athletic care medical team's target responders equipped with an AED. In practice, the athletic care medical team trained as target responders should immediately start BLS, including airway management, CPR (within 1 minute), and early defibrillation (within 2 minutes). Advanced life-saving measures follow when EMS paramedics arrive (within 5 minutes) to further stabilize and then transport the patient to a designated advanced life support facility. The transfer of the athlete's care from the athletic care medical team to EMS requires integration of the athletic care emergency medical plan with the community EMS emergency care plan.
In summary, a well-organized athletic care emergency plan should include all medical persons, regardless of discipline, capable of contributing to an improvement in the survival rate of an athlete having a sudden cardiac arrest. That plan also should provide training and recertification programs and assistance in supplying equipment for implementation of this type of comprehensive program. This funding should be a financial project of the university and not a budget item of the athletic department. Linking the school's athletic medical coverage to the community EMS programs will benefit everyone involved. It has been demonstrated that a community willing to altruistically become “its brother's keeper” through such a program has witnessed improved survival rates for a treatable cause of death in our society—sudden cardiac arrest.22