Cardiac pathologic findings reveal a high rate of sudden cardiac death of undetermined etiology in younger women

Sudden cardiac death in the young: A consensus statement on recommended practices for cardiac examination by pathologists from the Society for Cardiovascular Pathology

Sudden cardiac death is, by definition, an unexpected, untimely death caused by a cardiac condition in a person with known or unknown heart disease. This major international public health problem accounts for approximately 15-20% of all deaths. Typically more common in older adults with acquired heart disease, SCD also can occur in the young where the cause is more likely to be a genetically transmitted process. As these inherited disease processes can affect multiple family members, it is critical that these deaths are appropriately and thoroughly investigated. Across the United States, SCD cases in those less than 40 years of age will often fall under medical examiner/coroner jurisdiction resulting in scene investigation, review of available medical records and a complete autopsy including toxicological and histological studies. To date, there have not been consistent or uniform guidelines for cardiac examination in these cases. In addition, many medical examiner/coroner offices are understaffed and/or underfunded, both of which may hamper specialized examinations or studies (e.g., molecular testing). Use of such guidelines by pathologists in cases of SCD in decedents aged 1-39 years of age could result in life-saving medical intervention for other family members. These recommendations also may provide support for underfunded offices to argue for the significance of this specialized testing. As cardiac examinations in the setting of SCD in the young fall under ME/C jurisdiction, this consensus paper has been developed with members of the Society of Cardiovascular Pathology working with cardiovascular pathology-trained, practicing forensic pathologists.

Malignant Mitral Valve Prolapse: Risk and Prevention of Sudden Cardiac Death

Purpose of review

The purpose of this review is to explore the prevalence and risk factors for a malignant phenotype in mitral valve prolapse (MVP) characterized by life-threatening ventricular arrhythmias and sudden cardiac arrest and death (SCD), including mechanistic and pathophysiologic findings and mechanism-based potential therapies.

Recent findings

A malignant phenotype in MVP characterized by life-threatening arrhythmias has long been recognized, although MVP is often benign. Efforts to identify this malignant phenotype have revealed potential risk factors for SCD that include elongated, myxomatous leaflets, ECG changes and complex ventricular ectopy. More recently, malignant MVP has been associated with myocardial fibrosis in the papillary muscles and inferobasal left ventricular wall. This localization suggests a central role of prolapse-induced mechanical forces on the myocardium in creating an arrhythmogenic substrate and triggering life-threatening arrhythmias. This mechanism for fibrosis is also consistent with imaging evidence of prolapse-induced mechanical changes in the papillary muscles and inferobasal left ventricular wall. Currently, no therapy to prevent SCD in malignant MVP has been established and limited clinical data are available. Mechanistic information and prospective study have the potential to identify patients at risk of SCD and preventive strategies.

Summary

Malignant MVP relates to unique properties and mechanical abnormalities in the mitral valve apparatus and adjacent myocardium. Increased understanding of disease mechanisms and determinants of arrhythmias is needed to establish effective therapies.

Sex Disparities in Sudden Cardiac Death

The overall incidence of sudden cardiac death is considerably lower among women than men, reflecting significant and often under-recognized sex differences. Women are older at time of sudden cardiac death, less likely to have a prior cardiac diagnosis, and less likely to have coronary artery disease identified on postmortem examination. They are more likely to experience their death at home, during sleep, and less likely witnessed. Women are also more likely to present in pulseless electrical activity or systole rather than ventricular fibrillation or ventricular tachycardia. Conversely, women are less likely to receive bystander cardiopulmonary resuscitation or receive cardiac intervention post-arrest. Underpinning sex disparities in sudden cardiac death is a paucity of women recruited to clinical trials, coupled with an overall lack of prespecified sex-disaggregated evidence. Thus, predominantly male-derived data form the basis of clinical guidelines. This review outlines the critical sex differences concerning epidemiology, cause, risk factors, prevention, and outcomes. We propose 4 broad areas of importance to consider: physiological, personal, community, and professional factors.

Sex and Racial Differences in Autopsy-Defined Causes of Presumed Sudden Cardiac Death

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Gender differences in sudden cardiac death in the young-a nationwide study

Background

Hitherto, sudden cardiac death (SCD) in the young has been described with no distinction between genders. SCD occurs more often in men (SCDm) than women (SCDw), but this disparity is not understood and has not been investigated systematically in a nationwide setting. Our objective was to report gender differences in SCD in the young in a nationwide (Denmark) setting.

Methods

All deaths in persons aged 1–35 years nationwide in Denmark between 2000 and 2009 were included. Death certificates and autopsy reports were obtained. The extensive health care registries in Denmark were used to investigate any known disease prior to death. SCDw were compared to SCDm.

Results

During the 10-year study period there were a total of 8756 deaths in 23.7 million person-years. In total, 635 deaths were SCD. SCDw constituted 205 deaths (32%). Women had a higher proportion of witnessed deaths (51 vs. 41%, p = 0.02) and died less often in a public place (16 vs. 26%, p = 0.01). Age at death, ratios of autopsies and sudden unexplained deaths, and comorbidities, did not differ. Causes of SCD were largely comparable between genders. The incidence rate of SCDw was half of that of SCDm (1.8 vs. 3.6 per 100,000 person-years, incidence rate ratio 2.0 (95% CI 1.7–2.4), p < 0.01).

Conclusions

Incidence rate ratio of SCDm vs SCDw is 2. Young SCDw and SCDm are equally investigated, have comparable comorbidity, and causes of SCD. SCD due to potentially inherited cardiac diseases is less often in young women and could reflect a protection of female gender.

Acute Myocardial Infarction in Women: A Scientific Statement From the American Heart Association

Cardiovascular disease is the leading cause of mortality in American women. Since 1984, the annual cardiovascular disease mortality rate has remained greater for women than men; however, over the last decade, there have been marked reductions in cardiovascular disease mortality in women. The dramatic decline in mortality rates for women is attributed partly to an increase in awareness, a greater focus on women and cardiovascular disease risk, and the increased application of evidence-based treatments for established coronary heart disease. This is the first scientific statement from the American Heart Association on acute myocardial infarction in women. Sex-specific differences exist in the presentation, pathophysiological mechanisms, and outcomes in patients with acute myocardial infarction. This statement provides a comprehensive review of the current evidence of the clinical presentation, pathophysiology, treatment, and outcomes of women with acute myocardial infarction.

The spectrum of epidemiology underlying sudden cardiac death

Sudden cardiac death (SCD) from cardiac arrest is a major international public health problem accounting for an estimated 15%-20% of all deaths. Although resuscitation rates are generally improving throughout the world, the majority of individuals who experience a sudden cardiac arrest will not survive. SCD most often develops in older adults with acquired structural heart disease, but it also rarely occurs in the young, where it is more commonly because of inherited disorders. Coronary heart disease is known to be the most common pathology underlying SCD, followed by cardiomyopathies, inherited arrhythmia syndromes, and valvular heart disease. During the past 3 decades, declines in SCD rates have not been as steep as for other causes of coronary heart disease deaths, and there is a growing fraction of SCDs not due to coronary heart disease and ventricular arrhythmias, particularly among certain subsets of the population. The growing heterogeneity of the pathologies and mechanisms underlying SCD present major challenges for SCD prevention, which are magnified further by a frequent lack of recognition of the underlying cardiac condition before death. Multifaceted preventative approaches, which address risk factors in seemingly low-risk and known high-risk populations, will be required to decrease the burden of SCD. In this Compendium, we review the wide-ranging spectrum of epidemiology underlying SCD within both the general population and in high-risk subsets with established cardiac disease placing an emphasis on recent global trends, remaining uncertainties, and potential targeted preventive strategies.

Sudden cardiac death in young adult

Cardiovascular disease represents one of the most important public health problem in the Western countries, with sudden cardiac death (SCD) being the most common cause of death in adults under 65 years of age. The objective of the present study is to evaluate the leading causes of SCD in young adults who died suddenly in Northern Portugal between 2007 and 2012. This study included 288 cases of 20- to 45-year-old adults who died suddenly of a cardiac cause and whose forensic autopsy was performed in the North Branch of the National Institute of Legal Medicine and Forensic Sciences between 2007 and 2012. Data included the cause of death, forensic autopsy findings, previous medical history and cardiovascular risk factors. The mean age of the population was 37.36 years. Coronary artery disease (CAD) was the leading cause of death, representing 55.6 % of all cases (92.5 % of men and 7.5 % of women). Females died mostly from probable primary arrhythmia. From those who died of coronary disease, 72 (25 % of total cases) had histological evidence of a fatal acute infarction. Age, previous coronary disease, hypercholesterolemia, smoking habits and alcohol consumption seem to be associated with an increased risk of SCD by CAD. A total of 55.6 % of deaths were attributed to CAD. Prevention of cardiovascular risk factors should therefore be considered to prevent atherosclerosis in young adults.

Roadway proximity and risk of sudden cardiac death in women

BACKGROUND

Sudden cardiac death (SCD) is a major source of mortality and is the first manifestation of heart disease for the majority of cases. Thus, there is a definite need to identify risk factors for SCD that can be modified at the population level. Exposure to traffic, measured by residential roadway proximity, has been shown to be associated with an increased risk of cardiovascular disease. Our objective was to determine whether roadway proximity was associated with an increased risk of SCD and to compare that risk with the risk of other coronary heart disease outcomes.

METHODS AND RESULTS

A total of 523 cases of SCD were identified over 26 years of follow-up among 107 130 members of the prospective Nurses' Health Study. We calculated residential distance to roadways at all residential addresses from 1986 to 2012. In age- and race-adjusted models, women living within 50 m of a major roadway had an elevated risk of SCD (hazard ratio=1.56; 95% confidence interval, 1.18-2.05). The association was attenuated but still statistically significant after controlling for potential confounders and mediators (hazard ratio=1.38; 95% confidence interval, 1.04-1.82). The equivalent adjusted hazard ratios for nonfatal myocardial infarction and fatal coronary heart disease were 1.08 (95% confidence interval, 0.96-1.23) and 1.24 (95% confidence interval, 1.03-1.50), respectively.

CONCLUSIONS

Among this sample of middle-aged and older women, roadway proximity was associated with elevated and statistically significant risks of SCD and fatal coronary heart disease, even after controlling for other cardiovascular risk factors.

Diffuse ventricular fibrosis is a late outcome of tachycardia-mediated cardiomyopathy after successful ablation

BACKGROUND

Successful arrhythmia ablation normalizes ejection fraction (EF) in tachycardia-mediated cardiomyopathy, but recurrent heart failure and late sudden death have been reported. The aim of this study was to characterize the left ventricle (LV) of tachycardia-mediated cardiomyopathy patients long after definitive arrhythmia cure.

METHODS AND RESULTS

Thirty-three patients with a history of successfully ablated incessant focal atrial tachycardia 64±36 months prior, and 20 healthy controls were recruited. At ablation, 18 patients had EF<50% (AT-low EF) that recovered within 3 months from 37±12 to 56±4% (P<0.001), whereas 15 patients had EF>55% (AT-normal EF). No subjects had EF of 50% to 55%. Subjects underwent echocardiography with speckle tracking and contrast-enhanced cardiac MRI with ventricular T1 mapping as an index of diffuse fibrosis. Contrast-enhanced cardiac MRI was performed using a clinical 1.5-T scanner and 0.2 mmol/kg gadolinium-diethylene triamine penta-acetic acid for contrast. Subject characteristics were similar across the 3 groups. Compared with AT-normal EF patients and controls, AT-low EF patients had lower EF (60±6 versus 64±4 and 65±4%; P<0.05), greater indexed LV end-diastolic volume (102±34 versus 84±14 and 85±16 mL/m(2); P<0.05), and greater indexed LV end-systolic volume (41±11 versus 31±7 and 30±8 mL/m(2); P<0.01) on contrast-enhanced cardiac MRI. Compared with controls, AT-low EF patients had reduced global LV corrected T1 time (442±53 versus 529±61; P<0.05) consistent with diffuse fibrosis.

CONCLUSIONS

Tachycardia-mediated cardiomyopathy patients exhibit differences in LV structure and function including diffuse fibrosis long after arrhythmia cure, indicating that recovery is incomplete.

Distinctive profile of sudden cardiac arrest in middle-aged vs. older adults: a community-based study

BACKGROUND

While sudden cardiac arrest (SCA) rates increase with age, middle-aged adults (35-59 years) may comprise a significant proportion of SCA cases in the community (30-40%). However, there is a lack of studies evaluating SCA risk factors specifically associated with this age-group of the population.

METHODS

Using prospective multiple-source surveillance methodology we identified cases of SCA ≥35 years in the ongoing Oregon Sudden Unexpected Death Study (Portland, Oregon metropolitan area, population≈1,000,000). Out-of-hospital SCA cases, aged 35-59 years were compared to older SCA cases (≥60 years) in a comprehensive analysis of clinical profile of SCA.

RESULTS

The middle-aged (n=753) compared to older (n=1251) cases were more likely to be male, obese, have sleep apnea and seizure disorder (all p≤0.001); and were less likely to have a history of hypertension, diabetes mellitus, known coronary artery disease, congestive heart failure and syncope (all p<0.01). In multivariable analyses the middle-aged group had higher likelihood of male sex (O.R. 1.67, 95% C.I. 1.29-2.18), obesity (2.20, 1.52-3.19), sleep apnea (2.30, 1.44-3.68) and seizure disorder (2.69, 1.64-4.42); and lower rates of known coronary artery disease (0.57, 0.43-0.74) and congestive heart failure (0.35, 0.25-0.48).

CONCLUSIONS

SCA in the middle-aged adult was distinguishable from older subjects by higher rates of obesity, sleep apnea and seizure disorder; and lower prevalence of traditional clinical risk markers. With the growing epidemic of obesity, these findings have implications for SCA burden; and suggest the need for a clinical and investigational focus on SCA prediction and prevention in the middle-aged adult, that is distinct from older adults.

Sudden cardiac death: epidemiology, circadian variation, and triggers

Sudden cardiac death (SCD) remains a major health issue accounting for over 5% of annual mortality in the Western world. There are several causes of SCD, most commonly, coronary artery disease. Although identifying the prodrome of SCD has attracted considerable interest, a large proportion of patients die before any medical contact is established. SCD onset seems to follow a circadian pattern, most likely because of exposure to endogenous and exogenous triggers. The aim of the present report is to review the current knowledge of epidemiology, patterns of onset, and triggers of SCD and present directions for future research with a focus on coronary artery disease.

Women have less severe and extensive coronary atherosclerosis in fatal cases of ischemic heart disease: an autopsy study

OBJECTIVE

The study aims to evaluate sex differences in extent and severity of coronary artery disease (CAD) and myocardial findings at autopsy among young people with fatal ischemic heart disease (IHD).

BACKGROUND

Women with acute coronary syndrome are less likely than men to display obstructive CAD at angiography. This suggests unique mechanisms of acute coronary syndrome exist in women or may reflect prehospital death of women with the most severe CAD.

METHODS

Reports of autopsies by the Office of the Chief Medical Examiner of New York City on people aged 21 to 54 years who died between January 1, 2006, and December 31, 2008, were reviewed. A total of 639 cases of death due to atherosclerotic or arteriosclerotic cardiovascular disease according to the medical examiner were analyzed. Significant CAD was defined as ≥75% cross-sectional area stenosis in an epicardial vessel or ≥50% left main.

RESULTS

Women were less likely to have obstructive CAD (63% vs 77% of men, P = .002). There was pathologic evidence of myocardial infarction (MI) in 43% of cases, 17% of which had nonobstructive CAD. Frequency of MI did not vary by sex overall (38% of women vs 45% of men, P = .18) or among those without significant CAD (23% vs 29%, P = .45).

CONCLUSIONS

Among young people determined at autopsy to have died of IHD, fewer women had obstructive CAD, consistent with angiographic data in other IHD syndromes. Pathologic evidence of MI may exist in the absence of obstructive CAD.

Increase in sudden death from coronary artery disease in young adults

BACKGROUND

Sudden cardiac death (SCD) is the most common cause of death in adults aged <65 years, making it a major public health problem. A growing incidence in coronary artery disease (CAD) in young individuals has been predicted in developed countries, which could in turn be associated with an increase in SCD in this population. The aim of the study was to assess the prevalence of CAD among autopsies of young individuals (<40 years) who had sudden death (SD).

METHODS

We selected all the autopsies referred to the Montreal Heart Institute and Maisonneuve-Rosemont Hospital from January 2002 to December 2006 that corresponded to individuals <40 years old who had died suddenly. For each decedent, the following data were collected: cause of death, autopsy findings, available clinical history, toxicological findings, and cardiovascular risk factors.

RESULTS

From a total of 1,260 autopsies, 243 fulfilled the inclusion criteria. Coronary artery disease was the main cause of SCD from age 20 years, representing the 37% of deaths in the group of 21 to 30 years old, and up to 80% of deaths in the group of 31 to 40 years old. Among individuals who died of CAD, 3-vessel disease was observed in 39.7% of cases. Moreover, among the whole population <40 years old, at least 1 significant coronary lesion was observed in 39.5% of cases, irrespective to the cause of death. In the multivariable analysis, an increased BMI (hazard ratio 1.1 for each kg/m(2), 95% CI 1.01-1.1) and hypercholesterolemia (hazard ratio 2.4, 95% CI 1.7-333.3) showed to be the modifiable factors related to an increased risk of SD from CAD.

CONCLUSIONS

In our population, CAD was the main cause of SD from age 20 years. These data bring into question whether present prevention strategies are sufficient and reinforce the need to extend prevention to younger ages.

N-terminal pro-B-type natriuretic peptide is associated with sudden cardiac death risk: the Cardiovascular Health Study

BACKGROUND

Sudden cardiac death (SCD), the cause of 250,000-450,000 deaths per year, is a major public health problem. The majority of those affected do not have a prior cardiovascular diagnosis. Elevated B-type natriuretic peptide levels have been associated with the risk of heart failure and mortality as well as with sudden death in women.

OBJECTIVE

The purpose of this study was to examine the relationship between N-terminal pro-B-type natriuretic peptide (NT-proBNP) and SCD in the Cardiovascular Health Study population.

METHODS

The risk of SCD associated with baseline NT-proBNP was examined in 5,447 participants. Covariate-adjusted Cox model regressions were used to estimate the hazard ratios of developing SCD as a function of baseline NT-proBNP.

RESULTS

Over a median follow-up of 12.5 years (maximum 16), there were 289 cases of SCD. Higher NT-proBNP levels were strongly associated with SCD, with an unadjusted hazard ratio of 4.2 (95% confidence interval [2.9, 6.1]; P <.001) in the highest quintile compared with in the lowest. NT-proBNP remained associated with SCD even after adjustment for numerous clinical characteristics and risk factors (age, sex, race, and other associated conditions), with an adjusted hazard ratio for the fifth versus the first quintile of 2.5 (95% confidence interval [1.6, 3.8]; P <.001).

CONCLUSION

NT-proBNP provides information regarding the risk of SCD in a community-based population of older adults, beyond other traditional risk factors. This biomarker may ultimately prove useful in targeting the population at risk with aggressive medical management of comorbid conditions.

Light-to-moderate alcohol consumption and risk of sudden cardiac death in women

BACKGROUND

Moderate alcohol intake is associated with lower risk of coronary heart disease (CHD), but the association with sudden cardiac death (SCD) is less clear. In men, heavy alcohol consumption may increase risk of SCD, whereas light-to-moderate alcohol intake may lower risk. There are no parallel data among women.

OBJECTIVE

The purpose of this study was to assess the association between alcohol intake and risk of SCD among women and to investigate how this risk compared to other forms of CHD.

METHODS

We conducted a prospective cohort study among 85,067 women from the Nurses' Health Study who were free of chronic disease at baseline. Alcohol intake was assessed every 4 years through questionnaires. Primary endpoints included SCD, fatal CHD, and nonfatal myocardial infarction.

RESULTS

We found a U-shaped association between alcohol intake and risk of SCD, with the lowest risk among women who drank 5.0-14.9 g/day of alcohol (P for quadratic trend = 0.02). Compared to abstainers, the multivariate relative risk (95% confidence interval) for SCD was 0.79 (0.55-1.14) for former drinkers, 0.77 (0.57-1.06) for 0.1-4.9 g/day, 0.64 (0.43-0.95) for 5.0-14.9 g/day, 0.68 (0.38-1.23) for 15.0-29.9 g/day, and 1.15 (0.70-1.87) for ≥30.0 g/day. In contrast, the relationship of alcohol intake and nonfatal and fatal CHD was more linear (P for linear trend <.001).

CONCLUSION

In this cohort of women, the relationship between light-to-moderate alcohol intake and SCD is U-shaped, with a nadir at 5.0-14.9 g/day. Low levels of alcohol intake do not raise the risk of SCD and may lower risk in women.

Association of early repolarization pattern on ECG with risk of cardiac and all-cause mortality: a population-based prospective cohort study (MONICA/KORA)

BACKGROUND

Early repolarization pattern (ERP) on electrocardiogram was associated with idiopathic ventricular fibrillation and sudden cardiac arrest in a case-control study and with cardiovascular mortality in a Finnish community-based sample. We sought to determine ERP prevalence and its association with cardiac and all-cause mortality in a large, prospective, population-based case-cohort study (Monitoring of Cardiovascular Diseases and Conditions [MONICA]/KORA [Cooperative Health Research in the Region of Augsburg]) comprised of individuals of Central-European descent.

METHODS AND FINDINGS

Electrocardiograms of 1,945 participants aged 35-74 y, representing a source population of 6,213 individuals, were analyzed applying a case-cohort design. Mean follow-up was 18.9 y. Cause of death was ascertained by the 9th revision of the International Classification of Disease (ICD-9) codes as documented in death certificates. ERP-attributable effects on mortality were determined by a weighted Cox proportional hazard model adjusted for covariables. Prevalence of ERP was 13.1% in our study. ERP was associated with cardiac and all-cause mortality, most pronounced in those of younger age and male sex; a clear ERP-age interaction was detected (p = 0.005). Age-stratified analyses showed hazard ratios (HRs) for cardiac mortality of 1.96 (95% confidence interval [CI] 1.05-3.68, p = 0.035) for both sexes and 2.65 (95% CI 1.21-5.83, p = 0.015) for men between 35-54 y. An inferior localization of ERP further increased ERP-attributable cardiac mortality to HRs of 3.15 (95% CI 1.58-6.28, p = 0.001) for both sexes and to 4.27 (95% CI 1.90-9.61, p<0.001) for men between 35-54 y. HRs for all-cause mortality were weaker but reached significance.

CONCLUSIONS

We found a high prevalence of ERP in our population-based cohort of middle-aged individuals. ERP was associated with about a 2- to 4-fold increased risk of cardiac mortality in individuals between 35 and 54 y. An inferior localization of ERP was associated with a particularly increased risk. Please see later in the article for the Editors' Summary.

Women have a lower prevalence of structural heart disease as a precursor to sudden cardiac arrest: The Ore-SUDS (Oregon Sudden Unexpected Death Study)

OBJECTIVES

Our aim was to utilize a community-based approach to identify sex-related differences in risk factors for sudden cardiac arrest (SCA).

BACKGROUND

There are significant sex-based differences in prevalence and manifestation of SCA. Any differences related to predictors of SCA in women versus men are likely to have implications for risk stratification and prevention.

METHODS

The Ore-SUDS (Oregon Sudden Unexpected Death Study) is an ongoing prospective investigation of SCA in the Portland, Oregon, metropolitan area (population approximately 1 million). All cases meeting criteria for SCA were ascertained using multiple sources. Medical records were reviewed to identify clinical conditions that may contribute to SCA risk, and comparisons were made between male and female SCA cases using Pearson's chi-square tests for categorical variables, t tests for continuous variables, and multivariate logistic regression analysis.

RESULTS

During 2002 to 2007, 1,568 adult SCA cases were identified (women 36% vs. men 64%; p < 0.0001) and women were older (mean age 71 +/- 14 years vs. 65 +/- 14 years, p < 0.0001). There were no significant sex differences in prevalence of obesity, dyslipidemia, history of chronic obstructive pulmonary disease/asthma, left ventricular (LV) hypertrophy, or history of myocardial infarction. In multivariate analysis, women were significantly less likely to have severe LV dysfunction (odds ratio: 0.51; 95% confidence interval: 0.31 to 0.84) or previously recognized coronary artery disease (odds ratio: 0.34; 95% confidence interval: 0.20 to 0.60) compared with men.

CONCLUSIONS

Women were significantly less likely than men to have a diagnosis of structural heart disease (LV dysfunction or coronary artery disease) before SCA. These findings suggest that fewer women may be eligible for prophylactic implantable cardioverter-defibrillator placement based on current guidelines and therefore may not have equal opportunity for prevention. Enhancement of SCA risk stratification may have even higher importance for women.

Intake of total trans, trans-18:1, and trans-18:2 fatty acids and risk of sudden cardiac death in women

BACKGROUND

Total intake of trans fat is associated with coronary heart disease (CHD), and recent reports in primarily male populations suggest that blood levels of specific trans isomers may have different effects on risk, particularly risk of sudden cardiac death (SCD).

METHODS

We prospectively examined the association between dietary intake of trans fat and SCD among 86,762 women from the Nurses' Health Study. Coronary heart disease risk factors, including diet and lifestyle factors, were updated via questionnaires every 2 to 4 years, beginning in 1980.

RESULTS

Over 26 years, we documented 317 SCD events. In the primary analysis, we found no significant association between intake of total trans fat, trans-18:1, or trans-18:2 isomers and risk of SCD. Compared to the lowest quintile of intake, the relative risk (95% CI) of SCD in the highest quintile was 1.28 (0.82-2.00) for total trans, 1.08 (0.64-1.83) for trans-18:1, and 1.19 (0.76-1.88) for trans-18:2. In a secondary prespecified analysis, total trans fat was significantly related to SCD among women who reported a diagnosis of CHD before SCD (relative risk 3.24, 95% CI 1.42-7.40 for the highest vs lowest quintile, P trend = .01); however, the test for interaction was not significant (P = .11).

CONCLUSIONS

In this large prospective cohort of women, neither dietary intake of trans fat nor the individual trans isomers, trans-18:1 and trans-18:2, were significantly associated with risk of SCD. However, trans fat intake may be associated with SCD risk among women with CHD, suggesting that trans fat intake may play a greater role in SCD risk among those with clinically manifest atherosclerosis.

Epidemiology of sudden cardiac death: clinical and research implications

The current annual incidence of sudden cardiac death in the United States is likely to be in the range of 180,000 to 250,000 per year. Coinciding with the decreased mortality from coronary artery disease, there is evidence pointing toward a significant decrease in rates of sudden cardiac death in the United States during the second half of the 20th century. However, the alarming rise in prevalence of obesity and diabetes in the first decade of the new millennium both in the United States and worldwide, would indicate that this favorable trend is unlikely to persist. We are likely to witness a resurgence of coronary artery disease and heart failure, as a result of which sudden cardiac death will have to be confronted as a shared and indiscriminate, worldwide public health problem. There is also increasing recognition of the fact that discovery of meaningful and relevant risk stratification and prevention methodologies will require careful prospective community-wide analyses, with access to large archives of DNA, serum, and tissue that link with well-phenotyped databases. The purpose of this review is to summarize current knowledge of sudden cardiac death epidemiology. We will discuss the significance and strengths of community-wide evaluations of sudden cardiac death, summarize recent observations from such studies, and finally highlight specific potential predictors that warrant further evaluation as determinants of sudden cardiac death in the general population.

Sudden cardiac death in younger adults: autopsy diagnosis as a tool for preventive medicine

Sudden death in children and younger adults can be caused by potentially heritable cardiovascular disorders, and the fatal outcome is often the first symptom in apparently healthy subjects. In these cases, a careful autopsy becomes the sole diagnostic tool to guide the clinical screening of the families. The aims of the present study were (1) to assess the pathological substrate of sudden cardiac death in children and younger adults (age, 1-40 years) in a large prospective series using strict morphological criteria; and (2) to perform cardiological assessment of the relatives of the deceased subjects with cardiomyopathies or structurally normal hearts, potentially consistent with a heritable cardiac disease. We studied 100 consecutive cases. Autopsy findings included coronary artery disease (30%, atherosclerotic in the majority of cases), cardiomyopathies (22%), and various cardiac abnormalities (28%). In the remaining 20% of cases, the presence of significant morphological abnormalities of the heart was ruled out. Twenty of 42 families in which the heart of the proband was either affected by a cardiomyopathy or failed to show significant structural abnormalities could be contacted and provided informed consent to cardiological assessment. A potentially inherited cardiac disease was diagnosed in 4 (20%). Molecular genetic analysis was restricted to 3 of these families and revealed a mutation in the ryanodine receptor type 2 gene (RyR2) in 1. Our results underline the implication of autopsy findings for relatives and the importance of cardiological screening of family members to uncover familial cardiomyopathies or genetic arrhythmias and to adopt the proper therapeutic and preventive strategies. Genetic testing is still time consuming and costly: accordingly, it should be restricted only to selected cases.

Population-based analysis of sudden cardiac death with and without left ventricular systolic dysfunction: two-year findings from the Oregon Sudden Unexpected Death Study

OBJECTIVES

We sought to evaluate the contribution of left ventricular (LV) dysfunction toward occurrence of sudden cardiac death (SCD) in the general population, and to identify distinguishing characteristics of SCD in the absence of LV dysfunction.

BACKGROUND

Patients who manifest warning symptoms and signs are more likely to undergo evaluation before SCD. Although prevalence of LV dysfunction in this subgroup may overestimate the prevalence in overall SCD, this is the only means of assessment in the general population.

METHODS

All cases of SCD in Multnomah County, Oregon (population 660,486; 2002 to 2004) were prospectively ascertained in the ongoing Oregon Sudden Unexpected Death Study. We retrospectively assessed LV ejection fraction (LVEF) among subjects who underwent evaluation of LV function before SCD (normal: > or =55%; mildly to moderately reduced: 36% to 54%; and severely reduced: < or =35%). Of a total of 714 SCD cases (annual incidence 54 per 100,000), LV function was assessed in 121 (17%).

RESULTS

The LVEF was severely reduced in 36 patients (30%), mildly to moderately reduced in 27 (22%), and normal in 58 (48%). Patients with normal LVEF were distinguishable by younger age (66 +/- 15 years vs. 74 +/- 10 years; p = 0.001), higher proportion of females (47% vs. 27%; p = 0.025), higher prevalence of seizure disorder (14% vs. 0%; p = 0.002), and lower prevalence of established coronary artery disease (50% vs. 81%; p < 0.001).

CONCLUSIONS

In this community-wide study, only one-third of the evaluated SCD cases had severe LV dysfunction meeting current criteria for prophylactic cardioverter-defibrillator implantation. The SCD cases with normal LV function had several distinguishing clinical characteristics. These findings support the aggressive development of alternative screening methods to enhance identification of patients at risk.

Gender differences in autonomic modulation of ventricular repolarization in humans

BACKGROUND

Gender differences in the incidence of ventricular arrhythmias have been reported and torsades de pointes associated with long QT syndrome are more common in women than men. Although increased sympathetic tone has an important role in vulnerability to arrhythmia, little is currently known regarding gender differences in the dynamic electrophysiological response to sympathetic stimulation. Therefore, we investigated whether there is a gender difference in humans with respect to the dynamic response of ventricular repolarization to beta-adrenergic stimulation and to autonomic blockade.

METHODS

Twelve-lead ECGs were continuously recorded during isoproterenol infusion (protocol 1) and autonomic blockade with propranolol and atropine infusion (protocol 2) in 24 healthy volunteers (12 men, 23 +/- 2 years; 12 women, 23 +/- 5 years). QT (QTc) intervals were measured at the baseline and at a heart rate of 75, 100, and 120 beats/min.

RESULTS

(1) The morphology of the T wave dynamically and transiently changed to bifid or biphasic during the acute phase of isoproterenol infusion. The incidence of these morphologic changes was higher in women than men (P < 0.05). (2) The QTc interval was initially prolonged and then shortened in both men and women during isoproterenol administration. However, QTc prolongation was significantly greater in women (0.44 +/- 0.02 to 0.55 +/- 0.03 sec) than men (0.42 +/- 0.03 to 0.51 +/- 0.04 sec; P < 0.05). (3) The QTc interval was significantly prolonged under autonomic blockade and the intrinsic QTc interval was longer in women than men (P < 0.05).

CONCLUSION

While sympathetic stimulation and autonomic blockade modulated the dynamics of ventricular repolarization in both sexes, it was more pronounced in women. This gender difference may partially account for the susceptibility of women to arrhythmogenesis.

A woman's body and her vascular system are unique. How should we care for them?

Women must now gain the phenomenal care justified by new biologic evidence and a comprehensive understanding of fundamental differences from men-that go well beyond secondary sexual characteristics.