Invited commentary: sex-steroid hormones and QT-interval duration

In this issue of the Journal, Zhang et al. (Am J Epidemiol. 2011;174(4):403-411) make a substantial contribution to research in the area of hormonal influences on cardiac repolarization by demonstrating an inverse association between testosterone levels and the Bazett's adjusted QT interval (QTc) and RR-adjusted QT interval in men but not in postmenopausal women. They suggest that testosterone levels might explain the difference in QTc-interval duration between men and women and could contribute to population variability in QTc-interval duration among men. In this commentary, the gender difference and the role of testosterone in human cardiac repolarization are addressed. In addition, the gender differences in the congenital long-QT syndrome, drug-induced ventricular arrhythmias, and sudden cardiac death are discussed.

Variation in rates of fatal coronary heart disease by neighborhood socioeconomic status: the atherosclerosis risk in communities surveillance (1992-2002)

PURPOSE

Racial and gender disparities in out-of-hospital deaths from coronary heart disease (CHD) have been well-documented, yet disparities by neighborhood socioeconomic status (nSES) have been less systematically studied in US population-based surveillance efforts.

METHODS

We examined the association of nSES, classified into tertiles, with 3,743 out-of-hospital fatal CHD events, and a subset of 2,191 events classified as sudden, among persons aged 35 to 74 years in four US communities under surveillance by the Atherosclerosis Risk in Communities (ARIC). Poisson generalized linear mixed models generated age-, race- (white, black) and gender-specific standardized mortality rate ratios and 95% confidence intervals (RR, 95% CI).

RESULTS

Regardless of nSES measure used, inverse associations of nSES with all out-of-hospital fatal CHD and sudden fatal CHD were seen in all race-gender groups. The magnitude of these associations was larger among women than men. Further, among blacks, associations of low nSES (vs. high nSES) were stronger for sudden cardiac deaths (SCD) than for all out-of-hospital fatal CHD.

CONCLUSIONS

Low nSES was associated with an increased risk of out-of-hospital CHD death and SCD. Measures of the neighborhood context are useful tools in population-based surveillance efforts for documenting and monitoring socioeconomic disparities in mortality over time.

Frequency of cardiac events at four years among initially asymptomatic filipinos with the Brugada type 1 electrocardiographic pattern

Brugada type 1 electrocardiographic (ECG) pattern occurs in 0.2% of Filipinos. A knowledge gap exists on the natural course of asymptomatic patients with Brugada type 1 ECG pattern. Most studies that reported cohort event rates were taken from hospitals or referral centers. This is the first cohort from an entire country where the subjects were selected randomly. The objective of this study was to describe the frequency of cardiac events at 4 and 6 years of 7 patients with Brugada type 1 ECG pattern of 3,907 patients previously screened from the general population of the Philippines during the National Nutrition and Health Survey. Personal interviews at year 4 using a structured questionnaire were conducted by 1 of the investigators. Occurrences of major (syncope, seizure, unexplained accidents, sudden death) and minor events in subjects and their first- and second-degree relatives were elicited. Six-year follow-up by text messaging was conducted to ascertain vital status and occurrence of cardiac events. All 7 patients with Brugada type 1 ECG pattern were men. Three of the 7 initially asymptomatic subjects (43%, 95 confidence interval 6 to 80) developed a major cardiac event by the fourth year. Those with events were younger than those without events. All 7 were alive by the sixth year. No additional events were noted between the fourth and sixth years. In conclusion, cardiac events are considerable in initially asymptomatic Filipinos with Brugada type 1 ECG pattern.

Long-term outcome of 4 Korean families with hypertrophic cardiomyopathy caused by 4 different mutations

BACKGROUND

We sought to describe the long-term outcome of individuals in 4 Korean families with hypertrophic cardiomyopathy (HCM) with known mutations.

HYPOTHESIS

Long-term clinical features of familial HCM might be characterized according to the mutation causing HCM.

METHODS

We performed long-term (mean, 13.1 y) clinical evaluations on 46 subjects from 4 Korean families with different mutations.

RESULTS

Myosin light chain 3 gene (MYL3) mutation was associated with late-onset HCM with relatively poor prognosis; 1 sudden cardiac death and 2 cases of heart failure with atrial fibrillation occurred among 12 subjects with this mutation. Myosin binding protein C gene (MYBPC3) mutation was associated with 2 cases of sudden cardiac death and 3 cases of heart failure among 7 affected members. Cardiac troponin I type 3 gene (TNNI3) mutation was associated with 5 deaths related to atrial fibrillation and stroke among 12 mutation-positive members. Myosin heavy chain 7 gene (MYH7) mutation was associated with 11 deaths in 15 affected members.

CONCLUSIONS

The clinical course was quite different for different HCM mutations. Even within the same family, individuals carrying the same mutation differed in disease expression and prognosis.

Clinical correlates and heritability of QT interval duration in blacks: the Jackson Heart Study

BACKGROUND

Electrocardiographic QT interval prolongation is a risk factor for sudden cardiac death and drug-induced arrhythmia. The clinical correlates and heritability of QT interval duration in blacks have not been well studied despite their higher risk for sudden cardiac death compared with non-Hispanic whites. We sought to investigate potential correlates of the QT interval and estimate its heritability in the Jackson Heart Study.

METHODS AND RESULTS

The Jackson Heart Study comprises a sample of blacks residing in Jackson, Miss, of whom 5302 individuals with data at the baseline examination were available for study. Jackson Heart Study participants on QT-altering medications, with bundle-branch block, paced rhythm, atrial fibrillation/flutter, or other arrhythmias were excluded, resulting in a sample of 4660 individuals eligible for analyses. The relation between QT and potential covariates was tested using multivariable stepwise linear regression. Heritability was estimated using Sequential Oligogenic Linkage Analysis Routine in a subset of 1297 Jackson Heart Study participants in 292 families; the remaining sample included unrelated individuals. In stepwise multivariable linear regression analysis, covariates significantly associated with QT interval duration included R-R interval, sex, QRS duration, age, serum potassium, hypertension, body mass index, coronary heart disease, diuretic use, and Sokolow-Lyon voltage (P < or = 0.01 for all). The heritability of QT interval duration in the age-, sex-, and R-R interval-adjusted model and in the fully adjusted model was 0.41 (SE, 0.07) and 0.40 (SE, 0.07; P < 10(-11) for both), respectively.

CONCLUSIONS

There is substantial heritability of adjusted QT interval in blacks, supporting the need for further investigation to identify its genetic determinants.

Multiple independent genetic factors at NOS1AP modulate the QT interval in a multi-ethnic population

Extremes of electrocardiographic QT interval are associated with increased risk for sudden cardiac death (SCD); thus, identification and characterization of genetic variants that modulate QT interval may elucidate the underlying etiology of SCD. Previous studies have revealed an association between a common genetic variant in NOS1AP and QT interval in populations of European ancestry, but this finding has not been extended to other ethnic populations. We sought to characterize the effects of NOS1AP genetic variants on QT interval in the multi-ethnic population-based Dallas Heart Study (DHS, n = 3,072). The SNP most strongly associated with QT interval in previous samples of European ancestry, rs16847548, was the most strongly associated in White (P = 0.005) and Black (P = 3.6×10⁻⁵) participants, with the same direction of effect in Hispanics (P = 0.17), and further showed a significant SNP × sex-interaction (P = 0.03). A second SNP, rs16856785, uncorrelated with rs16847548, was also associated with QT interval in Blacks (P = 0.01), with qualitatively similar results in Whites and Hispanics. In a previously genotyped cohort of 14,107 White individuals drawn from the combined Atherosclerotic Risk in Communities (ARIC) and Cardiovascular Health Study (CHS) cohorts, we validated both the second locus at rs16856785 (P = 7.63×10⁻⁸), as well as the sex-interaction with rs16847548 (P = 8.68×10⁻⁶). These data extend the association of genetic variants in NOS1AP with QT interval to a Black population, with similar trends, though not statistically significant at P<0.05, in Hispanics. In addition, we identify a strong sex-interaction and the presence of a second independent site within NOS1AP associated with the QT interval. These results highlight the consistent and complex role of NOS1AP genetic variants in modulating QT interval.

Racial disparity in the utilization of implantable-cardioverter defibrillators among patients with prior myocardial infarction and an ejection fraction of <or=35%

Age-adjusted sudden cardiac death rates are highest for black patients compared with other racial groups. The prophylactic implantation of an implantable cardioverter-defibrillator (ICD) provides a significant reduction in sudden cardiac death and overall mortality in patients after myocardial infarctions with significant left ventricular systolic dysfunction. The purpose of this study was to determine whether black patients with left ventricular systolic dysfunction were less likely than white patients to receive ICDs for the primary prevention of sudden cardiac death. Data from the National Registry to Advance Heart Health (ADVANCENT) were analyzed to determine which patients with histories of myocardial infarctions and ejection fractions<or=35% received ICDs for the primary prevention of sudden cardiac death. Multivariate logistic regression was used to evaluate the association of patients' race with ICD implantation. Overall, 7,830 patients were identified as eligible candidates for ICDs. Black patients (n=660) were younger, more often women, had less education, had more co-morbidities, and had a lower mean ejection fraction compared with white patients (n=7,170). More than 90% of the study population were insured, and approximately 88% of participants in the registry were enrolled by cardiologists. Blacks were significantly less likely than whites to receive ICDs (30% vs 41%, p<0.001). This difference in ICD use persisted after adjusting for demographics, clinical characteristics, and socioeconomic factors (odds ratio 0.62, 95% confidence interval 0.50 to 0.75, p<0.001). In conclusion, among patients at an increased risk for sudden cardiac death, blacks were significantly less likely to receive ICDs than whites.

Racial disparity and technology diffusion: the case of cardioverter defibrillator implants, 1996-2001

BACKGROUND

Although implantable cardioverter defibrillator (ICD) therapy is widely endorsed for preventing sudden cardiac death (SCD), prior research documented a large black-white disparity in ICD therapy among the elderly. No studies have examined this disparity among nonelderly adults or over time as ICD therapy became widely diffused.

OBJECTIVE

This study compares disparity in use of ICD therapy for 1996-1998 to 1999-2001 between African Americans and other adults.

METHODS

The National Hospital Discharge Survey is used to compare ICD utilization between black and other adults diagnosed with ventricular tachycardia, ventricular fibrillation or cardiac arrest.

RESULTS

Adjusting for patient and hospital characteristics, ICD use per 100 at-risk patients rose from 11.0 to 27.3 among African Americans and from 24.0 to 37.5 among other adults between 1996-1998 and 1999-2001. Although the disparity was evident throughout the study period, it declined by 40%. Compared with their nonblack counterparts, black adults at risk for SCD were five years younger on average (p < 0.01) and more likely to be female (p < 0.01).

CONCLUSIONS

As ICD therapy became more widely available, use of this technology increased faster for black versus other adults, and the disparity in use declined but was not eliminated. Policymakers and clinicians should focus on increasing access among underserved populations to promising new technologies. Research focusing only on the elderly may miss important racial disparities when there is a race difference in the age distribution of disease risk. Further research should explore the relationship of technology diffusion to disparities in health service use.

Association between angiotensin-converting enzyme gene polymorphisms and QT duration in a multiethnic population in Hawaii

OBJECTIVES

Recent studies have suggested that heart-rate corrected QT interval (QTc) in normal populations may be influenced by genetic factors. We report findings of a study of the relationship between QTc, increased QTc (> 440 ms) and angiotensin-converting enzyme (ACE) genotype in a multiethnic, population-based study completed in rural Hawaii.

METHODS

Blood samples were obtained while fasting and after an oral glucose challenge from 1452 individuals between 1997 and 2000. The clinical examination included an electrocardiogram. Medical histories, behavioral and socio-demographic information were obtained during the interview. Ethnicity was estimated by self-report. The insertion/deletion (I/D) polymorphism in intron 16 of the ACE gene was determined by polymerase chain reaction (PCR) from a random sample of 588 participants. Multiple linear and logistic regression was used to test for associations between QTc and ACE gene polymorphisms.

RESULTS

The overall crude prevalence of increased QTc was 21.2%. The prevalence of increased QTc was lowest among those with ACE DD genotype, and highest among those with ACE insertion/insertion (II) genotype. The adjusted odds ratio for increased QTc was 2.29 (95% CI 1.02-5.12) and 3.61 (95% CI 1.60-8.13) for ID and II genotypes, respectively, compared to the DD genotype. The test for trend was highly significant (p < 0.001).

CONCLUSIONS

The ACE insertion allele was associated with increased prevalence of prolonged QTc independent of ethnicity, age, gender, and BMI. These findings may implicate the ACE gene as an important genetic risk factor for cardiovascular disease morbidity and mortality.

A Comparison of ICD Implantations in the United States Versus Italy

BACKGROUND

The benefits conferred by implantable cardioverter defibrillators (ICDs) have expanded to primary prevention. The advancements in ICD therapy (ACT) registry in the United States and the Italian ICD registry (IIR) examine changing trends in ICD implantation in their respective countries. Data from these registries may be useful for comparison of transcontinental differences in ICD utilization.

METHODS

This study includes initial implantations in patients enrolled in ACT and IIR. A comparative analysis was performed for device indications based on primary or secondary prevention. Sub-group analyses by device types (single, dual chamber, or cardiac resynchronization) were performed.

RESULTS

This analysis included 4,547 primary implantations in ACT and 6,491 in IIR. The groups were similar with respect to age. There were 82% primary and 18% secondary prevention indications in ACT, versus 42% primary and 58% secondary prevention indications in IIR (P < 0.001). There was a significantly higher rate of dual chamber ICD implants in ACT than in IIR for both primary (35.7% vs 23.7%, P < 0.001) and secondary prevention (52.3% vs 36.9%, P < 0.001). Conversely, more CRT-D were implanted in IIR than in ACT (primary prevention 46.5% vs 32.0%; secondary prevention 29.0% vs 13.0%, P < 0.001).

CONCLUSIONS

Significant differences were observed in the types of indications for ICDs between ACT and IIR. Device prescription differed significantly between countries. The specific reasons for differences in ICD implantation patterns in these two countries are unclear. These observations warrant further investigations to determine if these differences are associated with different qualities of life and clinical outcomes.

Brugada Syndrome in Japan

The incidence of Brugada syndrome (BS) is relatively high in Japan compared with the rest of the world, ranging between 0.1% and 0.2% in the general population. BS in Japan, as in other countries, is most prevalent in middle-aged men, and has characteristics ECG changes, a high recurrence rate in symptomatic patients, and relatively low incidence of SCN5A mutations. In contrast, both the incidence of a family history of BS and/or sudden cardiac death and the rate of developing cardiac events in asymptomatic patients are less in Japan than in other countries. Increased vagal tone and/or decreased sympathetic activity are suggested as provoking cardiac events. Several factors should be evaluated in risk stratification for recurrence of life-threatening arrhythmias, because there appears to be no single determinant for risk stratification: spontaneous ST elevation of coved-type (Type 1), family history of sudden cardiac death, inducible ventricular tachycardia/ventricular fibrillation and positive late potentials. An implantable cardioverter defibrillator is recommended for patients with aborted sudden cardiac death.

Effectiveness of the implantable cardioverter defibrillator in blacks versus whites (from MADIT-II)

The aim of this study was to examine the effectiveness of implantable cardioverter-defibrillator (ICD) therapy in whites and blacks who were enrolled in the Multicenter Automatic Defibrillator Implantation Trial-II (MADIT-II). The study population involved 1,232 subjects, with 1,073 white patients (87%) and 102 black patients (8%). Univariate analyses revealed a significant reduction in mortality in white patients treated with ICD therapy (p <0.02), but not in black patients (p = 0.96). White patients had a significant reduction of sudden cardiac death (p <0.01), but no benefit was evident in black patients (p = 0.62). Adjusting for relevant covariates, the ICD therapy/conventional therapy hazard ratios for total mortality were favorable in whites (0.75, 95% confidence interval [CI] 0.55 to 1.02), but not in blacks (1.25, 95% CI 0.42 to 3.60); the hazard ratios for sudden cardiac death were significantly (p = 0.04) lower in whites (0.29, 95% CI 0.17 to 0.49) than in blacks (1.71, 95% CI 0.33 to 8.84). Interaction analyses revealed a pattern of progressive improvement in ICD efficacy in whites as the end point became more specific for arrhythmic death, with exactly the reverse for blacks. In conclusion, ICD therapy in MADIT-II was associated with a reduction in total mortality, cardiac death, and sudden cardiac death in whites but not in blacks.

Sudden death is less common than might be expected in underprivileged ethnic minorities at high cardiovascular risk

Sudden cardiac death can be the presenting feature of coronary disease. Limited epidemiological studies from the US suggest an increased prevalence of sudden death in the African-American community. There are no reports in UK minority communities. We present sudden death data from an area with a high density of underprivileged ethnic minority groups.

METHODS

Ambulance data forms and accident and emergency records of all sudden unexpected deaths bought to City Hospital Birmingham in 2002 were extracted by retrospective review. The clinical characteristics and timing of the events were defined and analysed on the basis of the ethnic origins of the victims.

RESULTS

The prevalence of sudden death amongst Caucasians was substantially greater than among minorities. Both Indo-Asians and Afro-Caribbean groups had a lower than expected sudden death rate. Caucasian patients more commonly demonstrated a ventricular fibrillation (VF) rhythm at presentation while Indo-Asians and Afro-Caribbean's demonstrated a non-VF rhythm (asystole and pulseless electrical activity (PEA). Collapse with syncope was more common in Afro-Caribbean subjects while Indo-Asian subjects more often arrested in transit. There were no differences in call or transfer times.

CONCLUSIONS

Despite a well-described pattern of more aggressive coronary disease, particularly noted in South Asian communities in the UK, the sudden death rate are not increased and may be decreased. This implies a potentially separate mechanism or a confounding cultural influence in these events.

QT dispersion in adult hypertensives

Increased QT dispersion is associated with sudden cardiac death in congestive cardiac failure, hypertrophic cardiomyopathy and following myocardial infarction. Patients with hypertension--in particular, those with left ventricular hypertrophy (LVH)--are also at greater risk of sudden cardiac death. We examined whether QT dispersion, which is easily obtained from a routine ECG, correlates with LVH. One-hundred untreated patients with systemic hypertension and 78 normotensives had QT dispersion measured manually from a surface 12-lead electrocardiogram and two-dimensional echocardiography performed to measure interventricular septal thickness, posterior wall thickness and left ventricular internal diameter. Office blood pressure was also recorded. Multivariate analysis demonstrated significant relationships between QT dispersion and office systolic blood pressure, and left ventricular mass index. Manual measurement of QT dispersion might be a simple, noninvasive screening procedure to identify those hypertensives at greatest risk of sudden cardiac death in a third-world country.

HLa-class II (DRB & DQB1) in Thai sudden unexplained death syndrome (Thai SUDS) families (Lai-Tai families)

Thai Sudden Unexplained Death Syndrome (Thai SUDS), or Lai-Tai, is a major health problem among rural residents of northeastern Thailand. The cause has been identified as a genetic disease. SUDS, a disorder found in Southeast Asia, is characterized by an abnormal electrocardiogram with ST-segment elevation in leads V1-V3, identical to that seen in Brugada Syndrome (Brugada Sign, BS) and sudden death due to ventricular fibrillation and cardiac arrest (represents an arrhythmogenic marker that identifies high-risk for SUDS). SUDS victims have a sleeping disorder (narcolepsy). The HLA-DR locus is tightly associated with narcoleptic Japanese patients and HLA-DR2, DQ haplotypes were also found in Oriental narcoleptic patients. These circumstances prompted us to study the association between the disease and HLA Class II by HLA DNA typing using a PCR-SSO method, with five Thai SUDS families (18 BS-positive subjects as the cases, and 27 BS-negatives as the controls). We found that the HLA-DRB1 *12021 allele was significantly increased in BS-positive subjects (p = 0.02; OR = 4.5), the same as the HLA-DRB1*12021-DQB1 *0301/09 haplotype (p = 0.01; OR = 7.95). Our data suggests that the HLA-DRB1* 12021 allele associated with BS and the HLA-DRB1*12021-DQB1 *0301/09 is a haplotype susceptible to arrhythmogenic markers that can identify a high risk for SUDS.

The incidence of coronary heart disease among Palestinians and Israelis in Jerusalem

BACKGROUND

Lifestyle factors relevant to coronary risk factors differ between Palestinians and Israelis. Both have been exposed, albeit differently, to the stressors of the long-term conflict. We determined the incidence of coronary heart disease, previously unreported in Palestinians, in these Mediterranean populations and made international comparisons with the MONICA Programme.

METHODS

We applied the rigorous World Health Organization MONICA protocol, which enables standardized international population-based comparisons, to determine all acute myocardial infarction events and coronary deaths among Palestinians and Israelis aged 25-74, residents of the Jerusalem district in 1997.

RESULTS

We confirmed a total of 265 coronary events among 76,200 Arabs and 698 among 226,500 Jews. Rates among Arabs were substantially higher than in Jews, particularly so in women. Age-adjusted rate ratios (RRs) for coronary events were 1.58 [95% confidence interval (95% CI) 1.34-1.87] among men and 2.37 (95% CI 1.81-3.10) among women. When restricted to coronary deaths, Arab: Jewish RRs were 2.79 (95% CI 2.09-3.73) in men and 2.66 (95% CI 1.77-4.00) in women. Compared with MONICA populations in 20 countries, Arabs ranked first in total coronary event rates and first in non-fatal myocardial infarction rates, exceeded populations in Finland, Scotland, and Northern Ireland, and showed striking differences from the participating Mediterranean centres.

CONCLUSIONS

Coronary risk appears to be particularly high in Palestinian Arabs. Determinants of these unexpected findings should be sought and prevention programmes initiated.

Disparities in the use of primary prevention and defibrillator therapy among blacks and women

OBJECTIVES

This study determines whether there are racial or gender disparities in the use of implantable cardioverter-defibrillator therapy for primary prevention of sudden cardiac death.

BACKGROUND

Primary prevention of sudden death with implantable cardioverter-defibrillator therapy has been shown to improve survival for high-risk patients with coronary artery disease and left ventricular dysfunction.

METHODS

The Center for Medicare and Medicaid Services Medicare database from the year 2002 was used to identify patients who were potential candidates for implantable cardioverter-defibrillator therapy on the basis of a combination of International Classification of Diseases, Ninth Revision, Clinical Modification codes that reflected the presence of an ischemic cardiomyopathy. This cohort was analyzed to determine which patients received implantable cardioverter-defibrillator therapy during the same year. The clinical characteristics of the potential implantable cardioverter-defibrillator candidates were compared with those who actually received an implantable cardioverter-defibrillator.

RESULTS

A total 132565 Medicare patients hospitalized during 2002 were identified as having an ischemic cardiomyopathy; 10370 (8%) of these patients underwent implantable cardioverter-defibrillator implantation during the same year. The percentage of patients who underwent implantable cardioverter-defibrillator implantation was higher for men compared with women (10.2% vs 3.5%; P<.001) and whites compared with blacks (8.1 vs 5.4; P<.001). After multivariate analysis, age, gender, and race remained independent predictors of implantable cardioverter-defibrillator implantation. Women with an ischemic cardiomyopathy were 65% less likely to receive implantable cardioverter-defibrillator therapy compared with men (P<.001), and black patients were 31% less likely to receive implantable cardioverter-defibrillator therapy compared with patients of other races (P < .001).

CONCLUSIONS

Use of implantable cardioverter-defibrillator therapy for primary prevention of sudden death among the elderly population identified as having an ischemic cardiomyopathy was significantly lower among women compared with men, and among blacks compared with whites. Further exploration of gender and racial barriers to appropriate implantable cardioverter-defibrillator use for primary prevention is needed.

Relationship of race to sudden cardiac death in competitive athletes with hypertrophic cardiomyopathy

OBJECTIVES

The goal of this study was to determine the impact of race on identification of hypertrophic cardiomyopathy (HCM).

BACKGROUND

Sudden death in young competitive athletes is due to a variety of cardiovascular diseases (CVDs) and, most commonly, HCM. These catastrophes have become an important issue for African Americans, although HCM has been previously regarded as rare in this segment of the U.S. population.

METHODS

We studied the relationship of race to the prevalence of CVDs causing sudden death in our national athlete registry, and compared these findings with a representative multicenter hospital-based cohort of patients with HCM.

RESULTS

Of 584 athlete deaths, 286 were documented to be due to CVD at ages 17 +/- 3 years; 156 (55%) were white, and 120 (42%) were African American. Most were male (90%), and 67% participated in basketball and football. Among the 286 cardiovascular deaths, most were due to HCM (n = 102; 36%) or anomalous coronary artery of wrong sinus origin (n = 37; 13%). Of the athletes who died of HCM, 42 (41%) were white, but 56 (55%) were African American. In contrast, of 1,986 clinically identified HCM patients, only 158 (8%) were African American (p < 0.001).

CONCLUSIONS

In this autopsy series, HCM represented a common cause of sudden death in young and previously undiagnosed African American male athletes, in sharp contrast with the infrequent clinical identification of HCM in a hospital-based population (i.e., by seven-fold). This discrepancy suggests that many HCM cases go unrecognized in the African American community, underscoring the need for enhanced clinical recognition of HCM to create the opportunity for preventive measures to be employed in high-risk patients with this complex disease.

Linkage analyses and SCN5A mutations screening in five sudden unexplained death syndrome (Lai-tai) families

Sudden Unexplained Death Syndrome (SUDS) (or in Thai Lai-tai) share the same ECG pattern as Brugada Syndrome: RSR' and ST segment elevation in V1 to V3. Brugada Syndrome is a genetic disorder with the inheritance pattern of autosomal dominant (using the ECG pattern and unexplained sudden death as phenotype) and the cardiac sodium channel gene (SCN5A) mutations caused this syndrome. To determine whether SUDS was associated with the same mutations as Brugada Syndrome, the authors performed a linkage studies on 5 SUDS families with the Brugada Syndrome ECG pattern and found one family could not be excluded from linkage to SCN5A. However, the direct sequencing in 8 reported mutations on exon 5, 12, 17, 18 and 28 in this family failed to demonstrate the mutations. It was concluded that SUDS mutations maybe a novel mutation different from previously reported mutations, further genetic studies in SCN5A and other candidate genes might elucidate the molecular basis of SUDS.

Traditional risk factors and the incidence of sudden coronary death with and without coronary thrombosis in blacks

BACKGROUND

Blacks have a high rate of sudden coronary death (SCD). We determined the rate of SCD in men and women 30 to 69 years of age in a 6-year period recorded at a state Medical Examiner's Office.

METHODS AND RESULTS

In a subset of 327 whites and 130 blacks, hearts were systematically studied to determine the extent of coronary disease, presence and type of thrombus (acute rupture, acute erosion, stable plaque), and heart weight. These parameters were correlated with the presence of conventional risk factors. The estimated rate of SCD in blacks was similar to that in whites under the age of 40 years but increased compared with whites with advancing age, becoming 1.5 times the rate for whites in the 7th decade (95% of the increase in the 6th decade was due to sudden death with stable plaque). Among the autopsied group with severe coronary atherosclerosis, HDL cholesterol was higher and hypertension more prevalent in blacks, but there was no difference in the prevalence of healed infarcts, plaque burden, heart weight, acute thrombi, or rates of diabetes, cigarette smoking, and total cholesterol.

CONCLUSIONS

When compared with a control autopsy group of 568 deaths, multivariate analysis showed a significant association in blacks between stable plaque and left ventricular hypertrophy (risk ratio, 7.6), type 1 diabetes (risk ratio, 3.6), hypertension (risk ratio, 3.5), elevated total cholesterol (risk ratio, 3.1) and type 2 diabetes (risk ratio, 2.9). Because these risk factors are associated with SCD in blacks, they may be important targets for reducing the disparately high rate of SCD in blacks as compared with whites.

The Hound of the Baskervilles effect: natural experiment on the influence of psychological stress on timing of death

OBJECTIVE

To determine whether cardiac mortality is abnormally high on days considered unlucky: Chinese and Japanese people consider the number 4 unlucky, white Americans do not.

DESIGN

Examination of cardiac and non-cardiac mortality on and around the fourth of each month in Chinese and Japanese subjects and white controls.

SETTING

United States.

SUBJECTS

All Chinese and Japanese (n=209 908) and white (n=47 328 762) Americans whose computerised death certificates were recorded between the beginning of January 1973 and the end of December 1998.

MAIN OUTCOME MEASURES

Ratio of observed to expected numbers of deaths on the fourth day of the month (expected number was estimated from mortality on other days of the month).

RESULTS

Cardiac mortality in Chinese and Japanese people peaked on the fourth of the month. The peak was particularly large for deaths from chronic heart disease (ratio of observed to expected deaths = 1.13, 95% confidence interval 1.06 to 1.21) and still larger for deaths from chronic heart disease in California (1.27, 1.15 to 1.39). Within this group, inpatients showed a particularly large peak on the fourth day(1.45, 1.19 to 1.81). The peak was not followed by a compensatory drop in number of deaths. White controls, matched on age, sex, marital status, hospital status, location, and cause of death, showed no similar peak in cardiac mortality.

CONCLUSIONS

Our findings of excess cardiac mortality on "unlucky" days are consistent with the hypothesis that cardiac mortality increases on psychologically stressful occasions. The results are inconsistent with nine other possible explanations for the findings-for example, the fourth day peak does not seem to occur because of changes in the patient's diet, alcohol intake, exercise, or drug regimens.

Sudden cardiac death in the United States, 1989 to 1998

BACKGROUND

Sudden cardiac death (SCD) is a major clinical and public health problem.

METHODS AND RESULTS

United States (US) vital statistics mortality data from 1989 to 1998 were analyzed. SCD is defined as deaths occurring out of the hospital or in the emergency room or as "dead on arrival" with an underlying cause of death reported as a cardiac disease (ICD-9 code 390 to 398, 402, or 404 to 429). Death rates were calculated for residents of the US aged >/=35 years and standardized to the 2000 US population. Of 719 456 cardiac deaths among adults aged >/=35 years in 1998, 456 076 (63%) were defined as SCD. Among decedents aged 35 to 44 years, 74% of cardiac deaths were SCD. Of all SCDs in 1998, coronary heart disease (ICD-9 codes 410 to 414) was the underlying cause on 62% of death certificates. Death rates for SCD increased with age and were higher in men than women, although there was no difference at age >/=85 years. The black population had higher death rates for SCD than white, American Indian/Alaska Native, or Asian/Pacific Islander populations. The Hispanic population had lower death rates for SCD than the non-Hispanic population. From 1989 to 1998, SCD, as the proportion of all cardiac deaths, increased 12.4% (56.3% to 63.9%), and age-adjusted SCD rates declined 11.7% in men and 5.8% in women. During the same time, age-specific death rates for SCD increased 21% among women aged 35 to 44 years.

CONCLUSIONS

SCD remains an important public health problem in the US. The increase in death rates for SCD among younger women warrants additional investigation.