Christine M. Albert

Prospective Study of C-Reactive Protein, Homocysteine, and Plasma Lipid Levels as Predictors of Sudden Cardiac Death

Background—Sudden cardiac death (SCD) is an important cause of mortality even among apparently healthy populations. However, our ability to identify those at risk for SCD in the general population is poor, and more specific markers are needed. Methods and Results—To compare and contrast the relative importance of C-reactive protein (CRP), homocysteine, and lipids as long-term predictors of SCD, we performed a prospective, nested, case-control analysis involving 97 cases of SCD among apparently healthy men enrolled in the Physician’s Health Study. Of these plasma markers measured, only baseline CRP levels were significantly associated with the risk of SCD over the ensuing 17 years of follow-up (P for trend=0.001). The increase in risk associated with CRP levels was primarily seen among men in the highest quartile, who were at a 2.78-fold increased risk of SCD (95% CI 1.35 to 5.72) compared with men in the lowest quartile. These results were not significantly altered in analyses that (in addition to the matching variables of age and smoking status) controlled for lipid parameters, homocysteine, and multiple cardiac risk factors (relative risk for highest versus lowest quartile 2.65, 95% CI 0.79 to 8.83;P for trend=0.03). In contrast to the positive relationship observed for CRP, neither homocysteine nor lipid levels were significantly associated with risk of SCD. Conclusions—These prospective data suggest that CRP levels may be useful in identifying apparently healthy men who are at an increased long-term risk of SCD.

Effect of Folic Acid and B Vitamins on Risk of Cardiovascular Events and Total Mortality Among Women at High Risk for Cardiovascular Disease: A Randomized Trial

CONTEXT Recent randomized trials among patients with preexisting cardiovascular disease (CVD) have failed to support benefits of B-vitamin supplementation on cardiovascular risk. Observational data suggest benefits may be greater among women, yet women have been underrepresented in published randomized trials. OBJECTIVE To test whether a combination of folic acid, vitamin B6, and vitamin B12 lowers risk of CVD among high-risk women with and without CVD. DESIGN, SETTING, AND PARTICIPANTS Within an ongoing randomized trial of antioxidant vitamins, 5442 women who were US health professionals aged 42 years or older, with either a history of CVD or 3 or more coronary risk factors, were enrolled in a randomized, double-blind, placebo-controlled trial to receive a combination pill containing folic acid, vitamin B6, and vitamin B12 or a matching placebo, and were treated for 7.3 years from April 1998 through July 2005. INTERVENTION Daily intake of a combination pill of 2.5 mg of folic acid, 50 mg of vitamin B6, and 1 mg of vitamin B12. MAIN OUTCOME MEASURES A composite outcome of myocardial infarction, stroke, coronary revascularization, or CVD mortality. RESULTS Compared with placebo, a total of 796 women experienced a confirmed CVD event (406 in the active group and 390 in the placebo group). Patients receiving active vitamin treatment had similar risk for the composite CVD primary end point (226.9/10,000 person-years vs 219.2/10,000 person-years for the active vs placebo group; relative risk [RR], 1.03; 95% confidence interval [CI], 0.90-1.19; P = .65), as well as for the secondary outcomes including myocardial infarction (34.5/10,000 person-years vs 39.5/10,000 person-years; RR, 0.87; 95% CI, 0.63-1.22; P = .42), stroke (41.9/10,000 person-years vs 36.8/10,000 person-years; RR, 1.14; 95% CI, 0.82-1.57; P = .44), and CVD mortality (50.3/10,000 person-years vs 49.6/10,000 person-years; RR, 1.01; 95% CI, 0.76-1.35; P = .93). In a blood substudy, geometric mean plasma homocysteine level was decreased by 18.5% (95% CI, 12.5%-24.1%; P < .001) in the active group (n = 150) over that observed in the placebo group (n = 150), for a difference of 2.27 micromol/L (95% CI, 1.54-2.96 micromol/L). CONCLUSION After 7.3 years of treatment and follow-up, a combination pill of folic acid, vitamin B6, and vitamin B12 did not reduce a combined end point of total cardiovascular events among high-risk women, despite significant homocysteine lowering. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00000541.

Prevention of atrial fibrillation: report from a national heart, lung, and blood institute workshop.

The National Heart, Lung, and Blood Institute convened an expert panel April 28 to 29, 2008, to identify gaps and recommend research strategies to prevent atrial fibrillation (AF). The panel reviewed the existing basic scientific, epidemiological, and clinical literature about AF and identified opportunities to advance AF prevention research. After discussion, the panel proposed the following recommendations: (1) enhance understanding of the epidemiology of AF in the population by systematically and longitudinally investigating symptomatic and asymptomatic AF in cohort studies; (2) improve detection of AF by evaluating the ability of existing and emerging methods and technologies to detect AF; (3) improve noninvasive modalities for identifying key components of cardiovascular remodeling that promote AF, including genetic, fibrotic, autonomic, structural, and electrical remodeling markers; (4) develop additional animal models reflective of the pathophysiology of human AF; (5) conduct secondary analyses of already-completed clinical trials to enhance knowledge of potentially effective methods to prevent AF and routinely include AF as an outcome in ongoing and future cardiovascular studies; and (6) conduct clinical studies focused on secondary prevention of AF recurrence, which would inform future primary prevention investigations.The National Heart, Lung, and Blood Institute convened an expert panel April 28-29, 2008 to identify gaps and recommend research strategies to prevent atrial fibrillation (AF). The panel reviewed the existing basic scientific, epidemiologic and clinical literature about AF, and identified opportunities to advance AF prevention research. After discussion, the panel proposed the following recommendations: 1) Enhance understanding of the epidemiology of AF in the population by systematically and longitudinally investigating symptomatic and asymptomatic AF in cohort studies; 2) Improve detection of AF by evaluating the ability of existing and emerging methods and technologies to detect AF; 3) Improve noninvasive modalities for identifying key components of cardiovascular remodeling that promote AF, including genetic, fibrotic, autonomic, structural and electrical remodeling markers; 4) Develop additional animal models reflective of the pathophysiology of human AF; 5) Conduct secondary analyses of already-completed clinical trials to enhance knowledge of potentially effective methods to prevent AF and routinely include AF as an outcome in ongoing and future cardiovascular studies; and 6) Conduct clinical studies focused on secondary prevention of AF recurrence, which would inform future primary prevention investigations.

Meta-analysis identifies six new susceptibility loci for atrial fibrillation

Atrial fibrillation is a highly prevalent arrhythmia and a major risk factor for stroke, heart failure and death. We conducted a genome-wide association study (GWAS) in individuals of European ancestry, including 6,707 with and 52,426 without atrial fibrillation. Six new atrial fibrillation susceptibility loci were identified and replicated in an additional sample of individuals of European ancestry, including 5,381 subjects with and 10,030 subjects without atrial fibrillation (P < 5 × 10−8). Four of the loci identified in Europeans were further replicated in silico in a GWAS of Japanese individuals, including 843 individuals with and 3,350 individuals without atrial fibrillation. The identified loci implicate candidate genes that encode transcription factors related to cardiopulmonary development, cardiac-expressed ion channels and cell signaling molecules.

Sudden Cardiac Death Prediction and Prevention Report From a National Heart, Lung, and Blood Institute and Heart Rhythm Society Workshop

Despite the significant decline in coronary artery disease (CAD) mortality in the second half of the 20th century,1 sudden cardiac death (SCD) continues to claim 250 000 to 300 000 US lives annually.2 In North America and Europe the annual incidence of SCD ranges between 50 to 100 per 100 000 in the general population.3,–,6 Because of the absence of emergency medical response systems in most world regions, worldwide estimates are currently not available.7 However, even in the presence of advanced first responder systems for resuscitation of out-of-hospital cardiac arrest, the overall survival rate in a recent North American analysis was 4.6%.8 SCD can manifest as ventricular tachycardia (VT), ventricular fibrillation (VF), pulseless electric activity (PEA), or asystole. In a significant proportion of patients, SCD can present without warning or a recognized triggering mechanism. The mean age of those affected is in the mid 60s, and at least 40% of patients will suffer SCD before the age of 65.4 Consequently, enhancement of methodologies for prediction and prevention of SCD acquires a unique and critical importance for management of this significant public health issue. Prediction and prevention of SCD is an area of active investigation, but considerable challenges persist that limit the efficacy and cost-effectiveness of available methodologies.7,9,10 It was recognized early on that optimization of SCD risk stratification will require integration of multi-disciplinary efforts at the bench and bedside, with studies in the general population.11,–,13 This integration has yet to be effectively accomplished. There is also increasing awareness that more investigation needs to be directed toward identification of early predictors of SCD.14 Significant advancements have occurred for risk prediction in the inherited channelopathies15,–,17 and …

Prevention of Fatal Arrhythmias in High-Risk Subjects by Fish Oil n-3 Fatty Acid Intake

Background— The long-chain n-3 fatty acids in fish have been demonstrated to have antiarrhythmic properties in experimental models and to prevent sudden cardiac death in a randomized trial of post–myocardial infarction patients. Therefore, we hypothesized that these n-3 fatty acids might prevent potentially fatal ventricular arrhythmias in high-risk patients. Methods and Results— Four hundred two patients with implanted cardioverter/defibrillators (ICDs) were randomly assigned to double-blind treatment with either a fish oil or an olive oil daily supplement for 12 months. The primary end point, time to first ICD event for ventricular tachycardia or fibrillation (VT or VF) confirmed by stored electrograms or death from any cause, was analyzed by intention to treat. Secondary analyses were performed for “probable” ventricular arrhythmias, “on-treatment” analyses for all subjects who had taken any of their oil supplements, and “on-treatment” analyses only of those subjects who were on treatment for at least 11 months. Compliance with double-blind treatment was similar in the 2 groups; however, the noncompliance rate was high (35% of all enrollees). In the primary analysis, assignment to treatment with the fish oil supplement showed a trend toward a prolonged time to the first ICD event (VT or VF) or of death from any cause (risk reduction of 28%; P=0.057). When therapies for probable episodes of VT or VF were included, the risk reduction became significant at 31%; P=0.033. For those who stayed on protocol for at least 11 months, the antiarrhythmic benefit of fish oil was improved for those with confirmed events (risk reduction of 38%; P=0.034). Conclusions— Although significance was not achieved for the primary end point, this study provides evidence that for individuals at high risk of fatal ventricular arrhythmias, regular daily ingestion of fish oil fatty acids may significantly reduce potentially fatal ventricular arrhythmias.

Prospective Study of Sudden Cardiac Death Among Women in the United States

Background—There are few data regarding the determinants of sudden cardiac death (SCD) in women, primarily because of their markedly lower rate of SCD compared with men. Nonetheless, existing data, although sparse, suggest possible gender differences in risk factors for SCD. Methods and Results—In this prospective cohort of 121 701 women aged 30 to 55 years at baseline, SCD was defined as death within 1 hour of symptom onset. From 1976 to 1998, 244 SCDs were identified. Although the risk of SCD increased markedly with age, the percentage of cardiac deaths that were sudden decreased. Most (69%) women who suffered a SCD had no history of cardiac disease before their death. However, almost all of the women who died suddenly (94%) had reported at least 1 coronary heart disease risk factor. Smoking, hypertension, and diabetes conferred markedly elevated (2.5- to 4.0-fold) risk of SCD, similar to that conferred by a history of nonfatal myocardial infarction (relative risk, 4.1; 95% confidence interval, 2.9 to 6.7). Family history of myocardial infarction before age 60 years and obesity were associated with moderate (1.6-fold) elevations in risk. With regard to mechanism, 88% of SCDs were classified as arrhythmic. In 76% of these, the first rhythm documented was ventricular tachycardia or ventricular fibrillation. Conclusions—These prospective data suggest that, as in men, coronary heart disease risk factors predict risk of SCD in women and that SCD is usually an arrhythmic death. Therefore, prevention of atherosclerosis or ventricular arrhythmias may reduce the incidence of SCD in women.

Fish and Long-Chain ω-3 Fatty Acid Intake and Risk of Coronary Heart Disease and Total Mortality in Diabetic Women

Background—Although several prospective cohort studies have found an inverse association between fish consumption and risk of coronary heart disease (CHD) or sudden cardiac death in the general population, limited data are available among diabetic patients. Methods and Results—We examined prospectively the association between intake of fish and &ohgr;-3 fatty acids and risk of CHD and total mortality among 5103 female nurses with diagnosed type 2 diabetes but free of cardiovascular disease or cancer at baseline. Between 1980 and 1996 (45 845 person-years of follow-up), we documented 362 incident cases of CHD (141 CHD deaths and 221 nonfatal myocardial infarctions) and 468 deaths from all causes. Compared with women who seldom consumed fish (<1 serving/mo), the relative risks (RRs) (95% CI) of CHD adjusted for age, smoking, and other established coronary risk factors were 0.70 (0.48 to 1.03) for fish consumption 1 to 3 times per month, 0.60 (0.42 to 0.85) for once per week, 0.64 (0.42 to 0.99) for 2 to 4 times per week, and 0.36 (0.20 to 0.66) for 5 or more times per week (P for trend=0.002). Higher consumption of fish was also associated with a significantly lower total mortality (multivariate RR=0.48 [0.29 to 0.80] for ≥5 times per week [P for trend=0.005]). Higher consumption of long-chain &ohgr;-3 fatty acids was associated with a trend toward lower incidence of CHD (RR=0.69 [95% CI 0.47 to 1.03], P for trend=0.10) and total mortality (RR=0.63 [95% CI, 0.45 to 0.88], P for trend=0.02). Conclusions—A higher consumption of fish and long-chain &ohgr;-3 fatty acids was associated with a lower CHD incidence and total mortality among diabetic women.

Epidemiology and Genetics of Sudden Cardiac Death

Sudden cardiac death (SCD) generally refers to an unexpected death from a cardiovascular cause in a person with or without preexisting heart disease. The specificity of this definition varies depending on whether the event was witnessed; however, most studies include cases that are associated with a witnessed collapse, death occurring within 1 hour of an acute change in clinical status, or an unexpected death that occurred within the previous 24 hours.1–3 Further, sudden cardiac arrest describes SCD cases with resuscitation records or aborted SCD cases in which the individual survived the cardiac arrest. The incidence of SCD in the United States ranges between 180 000 and 450 000 cases annually.4 These estimates vary owing to differences in SCD definitions and surveillance methods for case ascertainment.4,5 In recent prospective studies using multiple sources in the United States,6,7 Netherlands,8 Ireland,9 and China,10 SCD rates range from 50 to 100 per 100 000 in the general population.3 Despite the need for multiple sources of surveillance to provide a more accurate estimate of SCD incidence, it is clear that the overall burden in the population remains high. Although improvements in primary and secondary prevention have resulted in substantial declines in overall coronary heart disease (CHD) mortality over the past 30 years,11,12 SCD rates specifically have declined to a lesser extent.13–16 SCD still accounts for >50% of all CHD deaths and 15% to 20% of all deaths.17,18 For some segments of the population, rates are not decreasing19 and may actually be increasing.14,19 As a result, SCD prevention represents a major opportunity to further reduce mortality from CHD. Despite major advances in cardiopulmonary resuscitation20 and postresuscitation care, survival …

Nonsteroidal Antiinflammatory Drugs, Acetaminophen, and the Risk of Cardiovascular Events

Background— Although randomized trials of cyclooxygenase-2 (COX-2) inhibitors have shown increased cardiovascular risk, studies of nonselective, nonsteroidal antiinflammatory drugs (NSAIDs) and acetaminophen have been inconsistent. Methods and Results— We examined the influence of NSAIDs and acetaminophen on the risk of major cardiovascular events (nonfatal myocardial infarction, fatal coronary heart disease, nonfatal and fatal stroke) in a prospective cohort of 70 971 women, aged 44 to 69 years at baseline, free of known cardiovascular disease or cancer, who provided medication data biennially since 1990. During 12 years of follow-up, we confirmed 2041 major cardiovascular events. Women who reported occasional (1 to 21 d/mo) use of NSAIDs or acetaminophen did not experience a significant increase in the risk of cardiovascular events. However, after adjustment for cardiovascular risk factors, women who frequently (≥22 d/mo) used NSAIDs had a relative risk (RR) for a cardiovascular event of 1.44 (95% CI, 1.27 to 1.65) compared with nonusers, whereas those who frequently consumed acetaminophen had a RR of 1.35 (95% CI, 1.14 to 1.59). The elevated risk associated with frequent NSAID use was particularly evident among current smokers (RR=1.82; 95% CI, 1.38 to 2.42) and was absent among never smokers (Pinteraction=0.02). Moreover, we observed significant dose-response relations: Compared with nonusers, the RRs for a cardiovascular event among women who used ≥15 tablets per week were 1.86 (95% CI, 1.27 to 2.73) for NSAIDs and 1.68 (95% CI, 1.10 to 2.58) for acetaminophen. Conclusions— Use of NSAIDs or acetaminophen at high frequency or dose is associated with a significantly increased risk for major cardiovascular events, although more moderate use did not confer substantial risk.