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1.  Sex Differences in Platelet Reactivity and Cardiovascular and Psychological Response to Mental Stress in Patients With Stable Ischemic Heart Disease 
Although emotional stress is associated with ischemic heart disease (IHD) and related clinical events, sex-specific differences in the psychobiological response to mental stress have not been clearly identified.
We aimed to study the differential psychological and cardiovascular responses to mental stress between male and female patients with stable IHD.
Patients with stable IHD enrolled in the REMIT (Responses of Mental Stress–Induced Myocardial Ischemia to Escitalopram) study underwent psychometric assessments, transthoracic echocardiography, and platelet aggregation studies at baseline and after 3 mental stress tasks. Mental stress–induced myocardial ischemia (MSIMI) was defined as the development or worsening of regional wall motion abnormality, reduction of left ventricular ejection fraction (LVEF) ≥8% by transthoracic echocardiography, and/or ischemic ST-segment change on electrocardiogram during 1 or more of the 3 mental stress tasks.
In the 310 participants with known IHD (18% women, 82% men), most baseline characteristics were similar between women and men (including heart rate, blood pressure, and LVEF), although women were more likely to be nonwhite, living alone (p < 0.001), and unmarried (p < 0.001); they also had higher baseline depression and anxiety (p < 0.05). At rest, women had heightened platelet aggregation responses to serotonin (p = 0.007) and epinephrine (p = 0.004) compared with men. Following mental stress, women had more MSIMI (57% vs. 41%, p < 0.04), expressed more negative (p = 0.02) and less positive emotion (p < 0.001), and demonstrated higher collagen-stimulated platelet aggregation responses (p = 0.04) than men. Men were more likely than women to show changes in traditional physiological measures, such as blood pressure (p < 0.05) and double product.
In this exploratory analysis, we identified clear, measurable, and differential responses to mental stress in women and men. Further studies should test the association of sex differences in cardiovascular and platelet reactivity in response to mental stress and long-term outcomes. (Responses of Myocardial Ischemia to Escitalopram Treatment [REMIT]; NCT00574847)
PMCID: PMC4752118  PMID: 25323254
mental stress; myocardial ischemia; women
2.  Use and Outcomes of Antiarrhythmic Therapy in Patients with Atrial Fibrillation Receiving Oral Anticoagulation: Results from the ROCKET AF Trial 
Antiarrhythmic drugs (AAD) and anticoagulation are mainstays of atrial fibrillation (AF) treatment.
We aimed to study the use and outcomes of AAD therapy in anticoagulated AF patients.
Patients in the ROCKET AF trial (n=14,264) were grouped by AAD use at baseline: amiodarone, other AAD, or no AAD. Multivariable adjustment was performed to compare stroke, bleeding, and death across groups, as well as across treatment assignment (rivaroxaban or warfarin).
Of 14,264 patients randomized, 1681 (11.8%) were treated with an AAD (1144 [8%] with amiodarone, 537 [3.8%] with other AADs). Amiodarone-treated patients were less-often female (38% vs. 48%), had more persistent AF (64% vs. 40%), and more concomitant heart failure (71% vs. 41%) than patients receiving other AADs. Patients receiving no AAD more closely-resembled amiodarone-treated patients. Time in therapeutic range was significantly lower in warfarin-treated patients receiving amiodarone versus no AAD (50% vs. 58%, p<0.0001). Compared with no AAD, neither amiodarone (adjusted HR 0.98, 95% CI 0.74–1.31, p=0.9) nor other AADs (adjusted HR 0.66, 95% CI 0.37–1.17, p=0.15) were associated with increased mortality. Similar results were observed for embolic and bleeding outcomes. Rivaroxaban treatment effects in patients not on an AAD were consistent with the overall trial (primary endpoint adjusted HR 0.82, 95% CI 0.68–0.98, pinteraction=0.06; safety endpoint adjusted HR 1.12, 95% CI 0.90–1.24, pinteraction=0.33).
Treatment with AADs was not associated with increased morbidity or mortality in anticoagulated patients with AF. The influence of amiodarone on outcomes in patients receiving rivaroxaban requires further study.
PMCID: PMC4035424  PMID: 24833235
atrial fibrillation; antiarrhythmic drugs; rivaroxaban; warfarin; outcomes
3.  The Effect of Aspirin on Endothelial Progenitor Cell Biology: Preliminary Investigation of Novel Properties 
Thrombosis research  2010;126(3):10.1016/j.thromres.2009.11.017.
Atherosclerosis develops in an environment of endothelial injury and inflammation. Circulating endothelial progenitor cells (EPCs) are required for vascular repair and restoration of normal endothelial function. We tested the hypothesis that the nonselective cyclooxygenase (COX) inhibitor aspirin exerts an effect on circulating EPCs.
As part of a larger study evaluating the effect of aspirin dose in primary and secondary prevention, subjects (n=32) were assigned randomly to either 81mg or 325mg aspirin daily for two months, and circulating mononuclear cells were enumerated at the beginning of the study and after 2 months using fluorescent antibodies against CD34 and CD133 as well as based on aldehyde dehydrogenase (ALDH) activity. Brachial artery endothelial function via flow-mediated dilation (BAFMD) and light transmittance platelet aggregometry in response to physiologic agonists was also determined.
Subjects taking aspirin at the time of study entry had a lower numbers of CD133+/34+ cells compared to those not previously exposed (0.01% vs. 0.05% of MNCs, P<0.03). After 2 months, subjects randomized to 81 vs. 325 mg of ASA had no significant differences in the median numbers of EPCs, although mean numbers trended lower in the high dose group. Patients on chronic ASA therapy continued to have lower numbers of EPCs. Similar effects were observed in CD34 and CD 133 single-positive cells, as well as ALDHbr cells. BAFMD did not differ nor change significantly over time between aspirin dose groups. All patients had decreased ex vivo platelet aggregation in response to arachidonic acid and ADP stimulation.
Our preliminary studies suggest that aspirin exerts a time-dependent effect on circulating EPCs. Short-term exposure to differing doses of ASA had indeterminate effects on EPCs levels, suggesting that time of ASA exposure may play a more important role than dose. Determining the responsible mechanism(s) and the overall clinical relevance of these findings will require further investigation.
PMCID: PMC3834257  PMID: 20659762
4.  Effect of Escitalopram on Mental Stress-Induced Myocardial Ischemia: The Results of the REMIT Trial 
JAMA  2013;309(20):2139-2149.
Mental-stress-induced myocardial ischemia (MSIMI) is an intermediate surrogate endpoint representing the pathophysiological link between psychosocial risk factors and adverse outcomes of coronary heart disease (CHD). However, pharmacological interventions aimed at reducing MSIMI have not been well studied.
To examine the effects of 6 weeks of escitalopram treatment vs. placebo on MSIMI and other psychological stress-related biophysiological and emotional parameters.
Design, Setting, and Participants
The REMIT study is a randomized, double-blind, placebo-controlled trial of patients with clinically stable CHD and laboratory MSIMI. Enrollment occurred from 7/24/2007–8/24/2011 at a tertiary medical center.
Eligible participants were randomized 1:1 to receive escitalopram (dose began at 5 mg with titration to 20 mg/day in 3 weeks) or placebo over 6 weeks.
Main Outcome Measure
Occurrence of MSIMI, defined as (1) development or worsening of regional wall motion abnormality; (2) left ventricular ejection fraction reduction ≥8%; and/or (3) horizontal or downsloping ST-segment depression ≥1mm in ≥2 leads lasting for ≥3 consecutive beats during ≥1 of 3 mental tasks.
127 participants were randomized to escitalopram (n=64) or placebo (n=63); 112 (96.1%) completed endpoint assessments (n=56 in each arm). At the end of 6 weeks, more patients taking escitalopram (34.2% [95% CI, 25.4 to 43.0]) had absence of MSIMI during the 3 mental stressors compared with patients taking placebo (17.5% [95% CI, 10.4 to 24.5]) based on unadjusted multiple imputation model for intention-to-treat analysis. A significant difference favoring escitalopram was observed (OR=2.62 [95% CI, 1.06 to 6.44]). Rates of exercise-induced ischemia were slightly lower at 6 weeks in the escitalopram group (45.8% [95% CI, 36.6 to 55.0]) than in patients receiving placebo (52.5% [95% CI, 43.3 to 61.7]), compared with baseline escitalopram (49.2% [95% CI, 39.9 to 58.5]) vs placebo (56.7% [95% CI, 47.5 to 65.9]), but this difference was not statistically significant.
Conclusion and relevance
Among patients with stable CHD and baseline MSIMI, 6 weeks of escitalopram versus placebo resulted in lower prevalence of MSIMI. There was no difference in exercise-induced ischemia.
Trial Registration Identifier: NCT00574847
PMCID: PMC4378823  PMID: 23695483
5.  Depressive Symptoms and Mental Stress Induced Myocardial Ischemia in Patients with Coronary Heart Disease 
Psychosomatic medicine  2013;75(9):822-831.
The primary focus of this study was to examine associations between depressive symptoms and mental stress induced myocardial ischemia (MSIMI) in patients with coronary heart disease (CHD).
Adult patients with documented CHD were recruited for baseline mental stress and exercise stress screening testing as a part of the enrollment process of the REMIT trial. Patients were administered the Beck Depression Inventory II (BDI-II) and the Center for Epidemiologic Studies Depression Scale (CESD). Following a 24-48-hour Beta-blocker withdrawal, consented patients completed three mental stress tests followed by a treadmill exercise test. Ischemia was defined as 1) any development or worsening of any wall motion abnormality (WMA), 2) reduction of left ventricular ejection fraction (LVEF) ≥ 8% by transthoracic echocardiography, and/or ischemic ST-segment change by electrocardiography during stress testing. MSIMI was considered present when ischemia occurred in at least one mental test. Data were analyzed using logistic regression adjusting for age, gender, and resting left ventricular ejection fraction.
One hundred twenty five (44.2 %) of 283 patients were found to have MSIMI and 93 (32.9%) had ESIMI. Unadjusted analysis showed that BDI-II scores were positively associated with the probability of MSIMI (OR = .1.30: 95% CI 1.06 – 1.60, p = .013) and number of MSIMI positive tasks (all p < .005). These associations were still significant after adjustment for covariates (ps ≤ .05).
In CHD patients, depressive symptoms were associated with a higher probability of MSIMI. These observations may enhance our understanding of the mechanisms contributing to the association of depressive symptoms to future cardiovascular events.
PMCID: PMC4378828  PMID: 24163385
Mental stress induced myocardial ischemia; exercise induced myocardial ischemia; depressive symptoms; coronary heart disease
6.  Alternative Calculations of Individual Patient Time in Therapeutic Range While Taking Warfarin: Results From the ROCKET AF Trial 
In the ROCKET AF (Rivaroxaban–Once‐daily, oral, direct Factor Xa inhibition Compared with vitamin K antagonism for prevention of stroke and Embolism Trial in Atrial Fibrillation) trial, marked regional differences in control of warfarin anticoagulation, measured as the average individual patient time in the therapeutic range (iTTR) of the international normalized ratio (INR), were associated with longer inter‐INR test intervals. The standard Rosendaal approach can produce biased low estimates of TTR after an appropriate dose change if the follow‐up INR test interval is prolonged. We explored the effect of alternative calculations of TTR that more immediately account for dose changes on regional differences in mean iTTR in the ROCKET AF trial.
Methods and Results
We used an INR imputation method that accounts for dose change. We compared group mean iTTR values between our dose change–based method with the standard Rosendaal method and determined that the differences between approaches depended on the balance of dose changes that produced in‐range INRs (“corrections”) versus INRs that were out of range in the opposite direction (“overshoots”). In ROCKET AF, the overall mean iTTR of 55.2% (Rosendaal) increased up to 3.1% by using the dose change–based approach, depending on assumptions. However, large inter‐regional differences in anticoagulation control persisted.
TTR, the standard measure of control of warfarin anticoagulation, depends on imputing daily INR values for the vast majority of follow‐up days. Our TTR calculation method may better reflect the impact of warfarin dose changes than the Rosendaal approach. In the ROCKET AF trial, this dose change–based approach led to a modest increase in overall mean iTTR but did not materially affect the large inter‐regional differences previously reported.
Clinical Trial Registration
URL: Unique identifier: NCT00403767.
PMCID: PMC4392426  PMID: 25736441
anticoagulants; arrhythmia; embolism; prevention; risk factors
8.  Ischaemic cardiac outcomes in patients with atrial fibrillation treated with vitamin K antagonism or factor Xa inhibition: results from the ROCKET AF trial 
European Heart Journal  2013;35(4):233-241.
We investigated the prevalence of prior myocardial infarction (MI) and incidence of ischaemic cardiovascular (CV) events among atrial fibrillation (AF) patients.
Methods and results
In ROCKET AF, 14 264 patients with nonvalvular AF were randomized to rivaroxaban or warfarin. The key efficacy outcome for these analyses was CV death, MI, and unstable angina (UA). This pre-specified analysis was performed on patients while on treatment. Rates are per 100 patient-years. Overall, 2468 (17%) patients had prior MI at enrollment. Compared with patients without prior MI, these patients were more likely to be male (75 vs. 57%), on aspirin at baseline (47 vs. 34%), have prior congestive heart failure (78 vs. 59%), diabetes (47 vs. 39%), hypertension (94 vs. 90%), higher mean CHADS2 score (3.64 vs. 3.43), and fewer prior strokes or transient ischaemic attacks (46 vs. 54%). CV death, MI, or UA rates tended to be lower in patients assigned rivaroxaban compared with warfarin [2.70 vs. 3.15; hazard ratio (HR) 0.86, 95% confidence interval (CI) 0.73–1.00; P = 0.0509]. CV death, MI, or UA rates were higher in those with prior MI compared with no prior MI (6.68 vs. 2.19; HR 3.04, 95% CI 2.59–3.56) with consistent results for CV death, MI, or UA for rivaroxaban compared with warfarin in prior MI compared with no prior MI (P interaction = 0.10).
Prior MI was common and associated with substantial risk for subsequent cardiac events. Patients with prior MI assigned rivaroxaban compared with warfarin had a non-significant 14% reduction of ischaemic cardiac events.
PMCID: PMC3896862  PMID: 24132190
Atrial fibrillation; Myocardial infarction; Coronary artery disease; Outcomes; Factor Xa; Rivaroxaban; Warfarin
9.  Outcomes of Temporary Interruption of Rivaroxaban Compared With Warfarin in Patients With Nonvalvular Atrial Fibrillation 
Circulation  2014;129(18):1850-1859.
During long-term anticoagulation in atrial fibrillation, temporary interruptions (TIs) of therapy are common, but the relationship between patient outcomes and TIs has not been well studied. We sought to determine reasons for TI, the characteristics of patients undergoing TI, and the relationship between anticoagulant and outcomes among patients with TI.
Methods and Results
In the Rivaroxaban Once Daily, Oral, Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF), a randomized, double-blind, double-dummy study of rivaroxaban and warfarin in nonvalvular atrial fibrillation, baseline characteristics, management, and outcomes, including stroke, non–central nervous system systemic embolism, death, myocardial infarction, and bleeding, were reported in participants who experienced TI (3–30 days) for any reason. The at-risk period for outcomes associated with TI was from TI start to 30 days after resumption of study drug. In 14 236 participants who received at least 1 dose of study drug, 4692 (33%) experienced TI. Participants with TI were similar to the overall ROCKET AF population in regard to baseline clinical characteristics. Only 6% (n=483) of TI incidences involved bridging therapy. Stroke/systemic embolism rates during the at-risk period were similar in rivaroxaban-treated and warfarin-treated participants (0.30% versus 0.41% per 30 days; hazard ratio [confidence interval]=0.74 [0.36–1.50]; P=0.40). Risk of major bleeding during the at-risk period was also similar in rivaroxaban-treated and warfarin-treated participants (0.99% versus 0.79% per 30 days; hazard ratio [confidence interval]=1.26 [0.80–2.00]; P=0.32).
TI of oral anticoagulation is common and is associated with substantial stroke risks and bleeding risks that were similar among patients treated with rivaroxaban or warfarin. Further investigation is needed to determine the optimal management strategy in patients with atrial fibrillation requiring TI of anticoagulation.
Clinical Trial Registration
URL: Unique identifier: NCT00403767.
PMCID: PMC4206548  PMID: 24552831
anticoagulation; atrial fibrillation; stroke
10.  Funding opportunities for clinical investigators in the early stages of career development in cardiovascular research 
Contemporary cardiovascular research offers junior investigators the opportunity to explore the gamut of biomedical questions. Despite the recent reduction in the availability of funding mechanisms that have historically served as the primary pathways for investigators in the early stages of career development, there remain numerous traditional and non-traditional funding opportunities. This article highlights these opportunities in order to assist early career investigators in the development of a personalized research trajectory, which optimizes the potential for career success.
PMCID: PMC3906627  PMID: 23860882
Cardiovascular investigator; Grant opportunities; Funding; Junior researcher
11.  Factors Associated With Major Bleeding Events 
This study sought to report additional safety results from the ROCKET AF (Rivaroxaban Once-daily oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation).
The ROCKET AF trial demonstrated similar risks of stroke/systemic embolism and major/nonmajor clinically relevant bleeding (principal safety endpoint) with rivaroxaban and warfarin.
The risk of the principal safety and component bleeding endpoints with rivaroxaban versus warfarin were compared, and factors associated with major bleeding were examined in a multivariable model.
The principal safety endpoint was similar in the rivaroxaban and warfarin groups (14.9 vs. 14.5 events/100 patient-years; hazard ratio: 1.03; 95% confidence interval: 0.96 to 1.11). Major bleeding risk increased with age, but there were no differences between treatments in each age category (<65, 65 to 74, ≥75 years; pinteraction = 0.59). Compared with those without (n = 13,455), patients with a major bleed (n = 781) were more likely to be older, current/prior smokers, have prior gastrointestinal (GI) bleeding, mild anemia, and a lower calculated creatinine clearance and less likely to be female or have a prior stroke/transient ischemic attack. Increasing age, baseline diastolic blood pressure (DBP) ≥90 mm Hg, history of chronic obstructive pulmonary disease or GI bleeding, prior acetylsalicylic acid use, and anemia were independently associated with major bleeding risk; female sex and DBP <90 mm Hg were associated with a decreased risk.
Rivaroxaban and warfarin had similar risk for major/nonmajor clinically relevant bleeding. Age, sex, DBP, prior GI bleeding, prior acetylsalicylic acid use, and anemia were associated with the risk of major bleeding. (An Efficacy and Safety Study of Rivaroxaban With Warfarin for the Prevention of Stroke and Non-Central Nervous System Systemic Embolism in Patients With Non-Valvular Atrial Fibrillation: NCT00403767)
PMCID: PMC4206565  PMID: 24315894
anticoagulants; atrial fibrillation; hemorrhage
12.  Aspirin Exposure Reveals Novel Genes Associated with Platelet Function and Cardiovascular Events 
To develop RNA profiles that could serve as novel biomarkers for the response to aspirin.
Aspirin reduces death and myocardial infarction (MI) suggesting that aspirin interacts with biological pathways that may underlie these events.
We administered aspirin, followed by whole blood RNA microarray profiling, in a discovery cohort of healthy volunteers (HV1,n=50), and two validation cohorts of volunteers (HV2,n=53) or outpatient cardiology patients (OPC, n=25). Platelet function was assessed by platelet function score (PFS; HV1/HV2) or VerifyNow Aspirin (OPC). Bayesian sparse factor analysis identified sets of coexpressed transcripts, which were examined for association with PFS in HV1 and validated in HV2 and OPC. Proteomic analysis confirmed the association of validated transcripts in platelet proteins. Validated gene sets were tested for association with death/MI in two patient cohorts (n=587, total) from RNA samples collected at cardiac catheterization.
A set of 60 co-expressed genes named the “aspirin response signature” (ARS) was associated with PFS in HV1 (r = −0.31, p = 0.03), HV2 (r = −0.34, Bonferroni p = 0.03), and OPC (p = 0.046). Corresponding proteins for 17 ARS genes were identified in the platelet proteome, of which, six were associated with PFS. The ARS was associated with death/MI in both patient cohorts (odds ratio = 1.2, p = 0.01 and hazard ratio = 1.5, p = 0.001), independent of cardiovascular risk factors. Compared with traditional risk factors, reclassification (net reclassification index = 31 - 37%, p ≤ 0.0002) was improved by including the ARS or one of its genes, ITGA2B.
RNA profiles of platelet-specific genes are novel biomarkers for identifying those do not response adequately to aspirin and who are at risk for death/MI.
PMCID: PMC3786046  PMID: 23831034
aspirin; platelets; genes; myocardial infarction; biomarkers
13.  Higher risk of death and stroke in patients with persistent vs. paroxysmal atrial fibrillation: results from the ROCKET-AF Trial 
European Heart Journal  2014;36(5):288-296.
Anticoagulation prophylaxis for stroke is recommended for at-risk patients with either persistent or paroxysmal atrial fibrillation (AF). We compared outcomes in patients with persistent vs. paroxysmal AF receiving oral anticoagulation.
Methods and results
Patients randomized in the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET-AF) trial (n = 14 264) were grouped by baseline AF category: paroxysmal or persistent. Multivariable adjustment was performed to compare thrombo-embolic events, bleeding, and death between groups, in high-risk subgroups, and across treatment assignment (rivaroxaban or warfarin). Of 14 062 patients, 11 548 (82%) had persistent AF and 2514 (18%) had paroxysmal AF. Patients with persistent AF were marginally older (73 vs. 72, P = 0.03), less likely female (39 vs. 45%, P < 0.0001), and more likely to have previously used vitamin K antagonists (64 vs. 56%, P < 0.0001) compared with patients with paroxysmal AF. In patients randomized to warfarin, time in therapeutic range was similar (58 vs. 57%, P = 0.94). Patients with persistent AF had higher adjusted rates of stroke or systemic embolism (2.18 vs. 1.73 events per 100-patient-years, P = 0.048) and all-cause mortality (4.78 vs. 3.52, P = 0.006). Rates of major bleeding were similar (3.55 vs. 3.31, P = 0.77). Rates of stroke or systemic embolism in both types of AF did not differ by treatment assignment (rivaroxaban vs. warfarin, Pinteraction = 0.6).
In patients with AF at moderate-to-high risk of stroke receiving anticoagulation, those with persistent AF have a higher risk of thrombo-embolic events and worse survival compared with paroxysmal AF.
PMCID: PMC4313363  PMID: 25209598
Atrial fibrillation; Paroxysmal; Persistent; Anticoagulation; Outcomes
14.  Clinical characteristics and outcomes with rivaroxaban vs. warfarin in patients with non-valvular atrial fibrillation but underlying native mitral and aortic valve disease participating in the ROCKET AF trial 
European Heart Journal  2014;35(47):3377-3385.
We investigated clinical characteristics and outcomes of patients with significant valvular disease (SVD) in the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) trial.
Methods and results
ROCKET AF excluded patients with mitral stenosis or artificial valve prostheses. We used Cox regression to adjust comparisons for potential confounders. Among 14 171 patients, 2003 (14.1%) had SVD; they were older and had more comorbidities than patients without SVD. The rate of stroke or systemic embolism with rivaroxaban vs. warfarin was consistent among patients with SVD [2.01 vs. 2.43%; hazard ratio (HR) 0.83, 95% confidence interval (CI) 0.55–1.27] and without SVD (1.96 vs. 2.22%; HR 0.89, 95% CI 0.75–1.07; interaction P = 0.76). However, rates of major and non-major clinically relevant bleeding with rivaroxaban vs. warfarin were higher in patients with SVD (19.8% rivaroxaban vs. 16.8% warfarin; HR 1.25, 95% CI 1.05–1.49) vs. those without (14.2% rivaroxaban vs. 14.1% warfarin; HR 1.01, 95% CI 0.94–1.10; interaction P = 0.034), even when controlling for risk factors and potential confounders. In intracranial haemorrhage, there was no interaction between patients with and without SVD where the overall rate was lower among those randomized to rivaroxaban.
Many patients with ‘non-valvular atrial fibrillation’ have significant valve lesions. Their risk of stroke is similar to that of patients without SVD after controlling for stroke risk factors. Efficacy of rivaroxaban vs. warfarin was similar in patients with and without SVD; however, the observed risk of bleeding was higher with rivaroxaban in patients with SVD but was the same among those without SVD. Atrial fibrillation patients with and without SVD experience the same stroke-preventive benefit of oral anticoagulants.
PMCID: PMC4265383  PMID: 25148838
Fibrillation; Anticoagulants; Heart diseases; Regurgitation; Stenosis
15.  A Phase 2, randomized, partially blinded, active-controlled study assessing the efficacy and safety of variable anticoagulation reversal using the REG1 system in patients with acute coronary syndromes: results of the RADAR trial 
European Heart Journal  2012;34(31):2481-2489.
We sought to determine the degree of anticoagulation reversal required to mitigate bleeding, and assess the feasibility of using pegnivacogin to prevent ischaemic events in acute coronary syndrome (ACS) patients managed with an early invasive approach. REG1 consists of pegnivacogin, an RNA aptamer selective factor IXa inhibitor, and its complementary controlling agent, anivamersen. REG1 has not been studied in invasively managed patients with ACS nor has an optimal level of reversal allowing safe sheath removal been defined.
Methods and results
Non-ST-elevation ACS patients (n = 640) with planned early cardiac catheterization via femoral access were randomized 2:1:1:2:2 to pegnivacogin with 25, 50, 75, or 100% anivamersen reversal or heparin. The primary endpoint was total ACUITY bleeding through 30 days. Secondary endpoints included major bleeding and the composite of death, myocardial infarction, urgent target vessel revascularization, or recurrent ischaemia. Enrolment in the 25% reversal arm was suspended after 41 patients. Enrolment was stopped after three patients experienced allergic-like reactions. Bleeding occurred in 65, 34, 35, 30, and 31% of REG1 patients with 25, 50, 75, and 100% reversal and heparin. Major bleeding occurred in 20, 11, 8, 7, and 10% of patients. Ischaemic events occurred in 3.0 and 5.7% of REG1 and heparin patients, respectively.
At least 50% reversal is required to allow safe sheath removal after cardiac catheterization. REG1 appears a safe strategy to anticoagulate ACS patients managed invasively and warrants further investigation in adequately powered clinical trials of patients who require short-term high-intensity anticoagulation. Clinical Trials Registration: NCT00932100.
PMCID: PMC3895957  PMID: 22859796
Acute coronary syndromes; Anticoagulation reversal; REG1
16.  Genetic Regulation of Platelet Receptor Expression and Function: Application in Clinical Practice and Drug Development 
Understanding genetic contributions to platelet function could have profound clinical ramifications for personalizing platelet-directed pharmacotherapy, by providing insight into the risks and possible benefits associated with specific genotypes. This article represents an integrated summary of presentations related to genetic regulation of platelet receptor expression and function given at the Fifth Annual Platelet Colloquium in January 2010. It is supplemented with additional highlights from the literature covering 1) approaches to determining and evidence for the associations of genetic variants with platelet hypo- and hyperresponsive phenotypes, 2) the ramifications of these polymorphisms with regard to clinical responses to antiplatelet therapies, and 3) the role of platelet function/genetic testing in guiding antiplatelet therapy.
PMCID: PMC4118751  PMID: 21084706
17.  Relationship Between Time in Therapeutic Range and Comparative Treatment Effect of Rivaroxaban and Warfarin: Results From the ROCKET AF Trial 
Time in therapeutic range (TTR) is a standard quality measure of the use of warfarin. We assessed the relative effects of rivaroxaban versus warfarin at the level of trial center TTR (cTTR) since such analysis preserves randomized comparisons.
Methods and Results
TTR was calculated using the Rosendaal method, without exclusion of international normalized ratio (INR) values performed during warfarin initiation. Measurements during warfarin interruptions >7 days were excluded. INRs were performed via standardized finger‐stick point‐of‐care devices at least every 4 weeks. The primary efficacy endpoint (stroke or non‐central nervous system embolism) was examined by quartiles of cTTR and by cTTR as a continuous function. Centers with the highest cTTRs by quartile had lower‐risk patients as reflected by lower CHADS2 scores (P<0.0001) and a lower prevalence of prior stroke or transient ischemic attack (P<0.0001). Sites with higher cTTR were predominantly from North America and Western Europe. The treatment effect of rivaroxaban versus warfarin on the primary endpoint was consistent across a wide range of cTTRs (P value for interaction=0.71). The hazard of major and non‐major clinically relevant bleeding increased with cTTR (P for interaction=0.001), however, the estimated reduction by rivaroxaban compared with warfarin in the hazard of intracranial hemorrhage was preserved across a wide range of threshold cTTR values.
The treatment effect of rivaroxaban compared with warfarin for the prevention of stroke and systemic embolism is consistent regardless of cTTR.
PMCID: PMC4187517  PMID: 24755148
rivaroxaban; time in therapeutic range; warfarin
18.  The efficacy of ticagrelor is maintained in women with acute coronary syndromes participating in the prospective, randomized, PLATelet inhibition and patient Outcomes (PLATO) trial 
European Heart Journal  2014;35(23):1541-1550.
The aim of this study was to assess the relationship between sex and clinical outcomes and treatment-related complications in patients with ST-elevation or non-ST-elevation acute coronary syndromes (ACS) randomized to treatment with ticagrelor or clopidogrel in the PLATelet inhibition and patient Outcomes (PLATO) trial.
The associations between sex subgroup and the primary composite outcomes, secondary outcomes, and major bleeding endpoints as well as interaction of sex subgroup with treatment effects were analysed using Cox proportional-hazards models.
Sex was not significantly associated with the probability of the primary composite endpoint [adjusted hazard ratio (HR): 1.02 (0.91−1.16)], or other adverse cardiovascular endpoints. Ticagrelor was similarly more effective than clopidogrel in reducing rates of the primary endpoint in women 11.2 vs. 13.2% [adjusted HR: 0.88 (0.74−1.06)] and men 9.4 vs. 11.1% [adjusted HR: 0.86 (0.76−0.97)] (interaction P-value 0.78), all-cause death in women 5.8 vs. 6.8% [adjusted HR: 0.90 (0.69−1.16)] and men 4.0 vs. 5.7% [adjusted HR: 0.80 (0.67−0.96)] (interaction P-value 0.49), and definite stent thrombosis in women 1.2 vs. 1.4% [adjusted HR: 0.71 (0.36−1.38)] and men 1.4 vs. 2.1% [adjusted HR: 0.63 (0.45−0.89)] (interaction P-value 0.78). The treatments did not differ for PLATO-defined overall major bleeding complications in women [adjusted HR: 1.01 (0.83−1.23)] or men [adjusted HR: 1.10 (0.98−1.24)]. Sex had no significant association with these outcomes (interactions P = 0.43−0.88).
Female sex is not an independent risk factor for adverse clinical outcomes in moderate-to-high risk ACS patients. Ticagrelor has a similar efficacy and safety profile in men and women.
PMCID: PMC4057642  PMID: 24682844
Acute coronary syndromes; Sex; Platelets; P2Y12 receptor; Ticagrelor; Thrombosis
19.  Clinical strategies for selecting oral anticoagulants in patients with atrial fibrillation 
Atrial fibrillation is a common arrhythmia. One of the important aspects of the management of atrial fibrillation is stroke prevention. Warfarin has been the longstanding anticoagulant used for stroke prevention in patients with atrial fibrillation. There are now three novel oral anticoagulants, which have been studied in randomized controlled trials and subsequently approved by the Federal Drug Administration for stroke prevention in patients with atrial fibrillation. Special patient populations, including renal insufficiency, elderly, prior stroke, and extreme body weights, were represented to varying degrees in the clinical trials of the novel oral anticoagulants. Furthermore, there is variation in the pharmacokinetics and pharmacodynamics of each anticoagulant, which affect the patient populations differently. Patients and clinicians are faced with the task of selecting among the available anticoagulants, and this review is designed to be a tool for clinical decision-making.
PMCID: PMC3937965  PMID: 23846737
Atrial fibrillation; Anticoagulation; Novel oral anticoagulants; Stroke; Warfarin
20.  Prevalence and Clinical Characteristics of Mental Stress–Induced Myocardial Ischemia in Patients With Coronary Heart Disease 
The goal of this study was to evaluate the prevalence and clinical characteristics of mental stress–induced myocardial ischemia.
Mental stress–induced myocardial ischemia is prevalent and a risk factor for poor prognosis in patients with coronary heart disease, but past studies mainly studied patients with exercise-induced myocardial ischemia.
Eligible patients with clinically stable coronary heart disease, regardless of exercise stress testing status, underwent a battery of 3 mental stress tests followed by a treadmill test. Stress-induced ischemia, assessed by echocardiography and electrocardiography, was defined as: 1) development or worsening of regional wall motion abnormality; 2) left ventricular ejection fraction reduction ≥8%; and/or 3) horizontal or downsloping ST-segment depression ≥1 mm in 2 or more leads lasting for ≥3 consecutive beats during at least 1 mental test or during the exercise test.
Mental stress–induced ischemia occurred in 43.45%, whereas exercise-induced ischemia occurred in 33.79% (p = 0.002) of the study population (N = 310). Women (odds ratio [OR]: 1.88), patients who were not married (OR: 1.99), and patients who lived alone (OR: 2.24) were more likely to have mental stress–induced ischemia (all p < 0.05). Multivariate analysis showed that compared with married men or men living with someone, unmarried men (OR: 2.57) and married women (OR: 3.18), or living alone (male OR: 2.25 and female OR: 2.72, respectively) had higher risk for mental stress-induced ischemia (all p < 0.05).
Mental stress-induced ischemia is more common than exercise-induced ischemia in patients with clinically stable coronary heart disease. Women, unmarried men, and individuals living alone are at higher risk for mental stress-induced ischemia. (Responses of Myocardial Ischemia to Escitalopram Treatment [REMIT]; NCT00574847)
PMCID: PMC3913125  PMID: 23410543
mental and exercise stress; myocardial ischemia
21.  Hyperreactive platelet phenotypes: Relationship to altered serotonin transporter number, transport kinetics and intrinsic response to adrenergic co-stimulation 
Thrombosis and haemostasis  2012;109(1):85-92.
The mechanism underlying a hyperreactive platelet phenotype remains unknown. Since serotonin has been shown to influence platelet biology and atherothrombosis, we sought to investigate the association of platelet serotonin transporter number, binding affinity, and uptake kinetics to platelet aggregation. A total of 542 healthy volunteers had light transmittance platelet aggregometry measured in response to varying concentrations of epinephrine, serotonin, epinephrine plus serotonin, ADP and collagen. Transporter-dependent serotonin uptake rate was determined (Vmax), as were serotonin transporter number (Bmax) and binding affinity (Kd) using 3H paroxetine binding in a homologous displacement assay, nonlinear regression and validated algorithms for kinetic modeling. Stimulation with submaximal (2 μM) epinephrine concentration elicited a distinct, bimodal pattern of platelet aggregation in this population. In contrast, subjects exhibited minimal aggregation in response to serotonin alone. Co-stimulation with submaximal epinephrine and serotonin induced platelet aggregation to a level beyond that observed with either agonist alone and maintained a bimodal response distribution. Subjects with heightened (>60%) platelet aggregation to both epinephrine alone and epinephrine plus serotonin exhibited increased platelet serotonin uptake, and transporter number and affinity. In a population of healthy subjects, co-stimulation with submaximal concentrations of epinephrine and serotonin identifies a subset of individuals with a hyperreactive platelet aggregation profile that is associated with changes in platelet serotonin function.
PMCID: PMC3582386  PMID: 23223800
Platelets; platelet activity; serotonin; epinephrine; transporter
22.  A Functional Polymorphism in the 5HTR2C Gene Associated with Stress Responses Also Predicts Incident Cardiovascular Events 
PLoS ONE  2013;8(12):e82781.
Previously we have shown that a functional nonsynonymous single nucleotide polymorphism (rs6318) of the 5HTR2C gene located on the X-chromosome is associated with hypothalamic-pituitary-adrenal axis response to a stress recall task, and with endophenotypes associated with cardiovascular disease (CVD). These findings suggest that individuals carrying the rs6318 Ser23 C allele will be at higher risk for CVD compared to Cys23 G allele carriers. The present study examined allelic variation in rs6318 as a predictor of coronary artery disease (CAD) severity and a composite endpoint of all-cause mortality or myocardial infarction (MI) among Caucasian participants consecutively recruited through the cardiac catheterization laboratory at Duke University Hospital (Durham, NC) as part of the CATHGEN biorepository. Study population consisted of 6,126 Caucasian participants (4,036 [65.9%] males and 2,090 [34.1%] females). A total of 1,769 events occurred (1,544 deaths and 225 MIs; median follow-up time =  5.3 years, interquartile range  = 3.3–8.2). Unadjusted Cox time-to-event regression models showed, compared to Cys23 G carriers, males hemizygous for Ser23 C and females homozygous for Ser23C were at increased risk for the composite endpoint of all-cause death or MI: Hazard Ratio (HR)  = 1.47, 95% confidence interval (CI)  = 1.17, 1.84, p  = .0008. Adjusting for age, rs6318 genotype was not related to body mass index, diabetes, hypertension, dyslipidemia, smoking history, number of diseased coronary arteries, or left ventricular ejection fraction in either males or females. After adjustment for these covariates the estimate for the two Ser23 C groups was modestly attenuated, but remained statistically significant: HR  = 1.38, 95% CI = 1.10, 1.73, p = .005. These findings suggest that this functional polymorphism of the 5HTR2C gene is associated with increased risk for CVD mortality and morbidity, but this association is apparently not explained by the association of rs6318 with traditional risk factors or conventional markers of atherosclerotic disease.
PMCID: PMC3867393  PMID: 24386118
23.  Time-dependent changes in non-COX-1-dependent platelet function with daily aspirin therapy 
To develop an integrated metric of non COX-1 dependent platelet function (NCDPF) to measure the temporal response to aspirin in healthy volunteers and diabetics.
NCDPF on aspirin demonstrates wide variability, despite suppression of COX-1. Although a variety of NCDPF assays are available, no standard exists and their reproducibility is not established.
We administered 325mg/day aspirin to two cohorts of volunteers (HV1, n = 52, and HV2, n = 96) and diabetics (DM, n = 74) and measured NCDPF using epinephrine, collagen, and ADP aggregometry and PFA100 (collagen/epi) before (Pre), after one dose (Post), and after several weeks (Final). COX-1 activity was assessed with arachidonic acid aggregometry (AAA). The primary outcome of the study, the platelet function score (PFS), was derived from a principal components analysis of NCDPF measures.
The PFS strongly correlated with each measure of NCDPF in each cohort. After two or four weeks of daily aspirin the Final PFS strongly correlated (r > 0.7, p<0.0001) and was higher (p < 0.01) than the Post PFS. The magnitude and direction of the change in PFS (Final - Post) in an individual subject was moderately inversely proportional to the Post PFS in HV1 (r = −0.45), HV2 (r = −0.54), DM (r = −0.68), p<0.0001 for all. AAA remained suppressed during aspirin therapy.
The PFS summarizes multiple measures of NCDPF. Despite suppression of COX-1 activity, NCDPF during aspirin therapy is predictably dynamic: those with heightened NCDPF continue to decline whereas those with low/normal NCDPF return to pre-aspirin levels over time.
PMCID: PMC3337886  PMID: 22294277
aspirin; platelets; light transmittance aggregometry; PFA100; principal components analysis
25.  Impact of Global Geographic Region on Time in Therapeutic Range on Warfarin Anticoagulant Therapy: Data From the ROCKET AF Clinical Trial 
Vitamin K antagonist (VKA) therapy remains the most common method of stroke prevention in patients with atrial fibrillation. Time in therapeutic range (TTR) is a widely cited measure of the quality of VKA therapy. We sought to identify factors associated with TTR in a large, international clinical trial.
Methods and Results
TTR (international normalized ratio [INR] 2.0 to 3.0) was determined using standard linear interpolation in patients randomized to warfarin in the ROCKET AF trial. Factors associated with TTR at the individual patient level (i‐TTR) were determined via multivariable linear regression. Among 6983 patients taking warfarin, recruited from 45 countries grouped into 7 regions, the mean i‐TTR was 55.2% (SD 21.3%) and the median i‐TTR was 57.9% (interquartile range 43.0% to 70.6%). The mean time with INR <2 was 29.1% and the mean time with an INR >3 was 15.7%. While multiple clinical features were associated with i‐TTR, dominant determinants were previous warfarin use (mean i‐TTR of 61.1% for warfarin‐experienced versus 47.4% in VKA‐naïve patients) and geographic region where patients were managed (mean i‐TTR varied from 64.1% to 35.9%). These effects persisted in multivariable analysis. Regions with the lowest i‐TTRs had INR distributions shifted toward lower INR values and had longer inter‐INR test intervals.
Independent of patient clinical features, the regional location of medical care is a dominant determinant of variation in i‐TTR in global studies of warfarin. Regional differences in mean i‐TTR are heavily influenced by subtherapeutic INR values and are associated with reduced frequency of INR testing.
Clinical Trial Registration
URL: Unique identifier: NCT00403767.
PMCID: PMC3603243  PMID: 23525418
anticoagulants; arrhythmia; embolism; prevention; risk factors

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