Socioeconomic deprivation and racialised disparities in competitive athletes with sudden cardiac arrest from the USA

OBJECTIVE

To explore the association of socioeconomic deprivation and racialised outcomes in competitive athletes with sudden cardiac arrest (SCA) in the USA.

METHODS

SCA cases from the National Center for Catastrophic Sports Injury Research (July 2014 to June 2021) were included. We matched Area Deprivation Index (ADI) scores (17 metrics to grade socioeconomic conditions) to the 9-digit zip codes for each athlete's home address. ADI is scored 1-100 with higher scores indicating greater neighbourhood socioeconomic deprivation. Analysis of variance was used to assess differences in mean ADI by racial groups. Tukey post hoc testing was used for pairwise comparisons.

RESULTS

391 cases of SCA in competitive athletes (85.4% male; 16.9% collegiate, 68% high school, 10.7% middle school, 4.3% youth) were identified via active surveillance. 79 cases were excluded due to missing data (19 race, 60 ADI). Of 312 cases with complete data, 171 (54.8%) were white, 110 (35.3%) black and 31 (9.9%) other race. The mean ADI was 40.20 (95% CI 36.64, 43.86) in white athletes, 57.88 (95% CI 52.65, 63.11) in black athletes and 40.77 (95% CI 30.69, 50.86) in other race athletes. Mean ADI was higher in black versus white athletes (mean difference 17.68, 95% CI 10.25, 25.12; p=0.0036) and black versus other race athletes (mean difference 17.11, 95% CI 4.74, 29.47; p<0.0001).

CONCLUSIONS

Black athletes with SCA come from areas with higher neighbourhood socioeconomic deprivation than white or other race athletes with SCA. Our findings suggest that socioeconomic deprivation may be associated with racialised disparities in athletes with SCA.

Risk Factors for Sudden Cardiac Arrest Among Hispanic or Latino Adults in Southern California: Ventura PRESTO and HCHS/SOL

Background Out-of-hospital sudden cardiac arrest (SCA) is a leading cause of mortality, making prevention of SCA a public health priority. No studies have evaluated predictors of SCA risk among Hispanic or Latino individuals in the United States. Methods and Results In this case-control study, adult SCA cases ages 18-85 (n=1,468) were ascertained in the ongoing Ventura Prediction of Sudden Death in Multi-Ethnic Communities (PRESTO) study (2015-2021) in Ventura County, California. Control subjects were selected from 3033 Hispanic or Latino participants who completed Visit 2 examinations (2014-2017) at the San Diego site of the HCHS/SOL (Hispanic Community Health Survey/Study of Latinos). We used logistic regression to evaluate the association of clinical factors with SCA. Among Hispanic or Latino SCA cases (n=295) and frequency-matched HCHS/SOL controls (n=590) (70.2% men with mean age 63.4 and 61.2 years, respectively), the following clinical variables were associated with SCA in models adjusted for age, sex, and other clinical variables: chronic kidney disease (odds ratio [OR], 7.3 [95% CI, 3.8-14.3]), heavy drinking (OR, 4.5 [95% CI, 2.3-9.0]), stroke (OR, 3.1 [95% CI, 1.2-8.0]), atrial fibrillation (OR, 3.7 [95% CI, 1.7-7.9]), coronary artery disease (OR, 2.9 [95% CI, 1.5-5.9]), heart failure (OR, 2.5 [95% CI, 1.2-5.1]), and diabetes (OR, 1.5 [95% CI, 1.0-2.3]). Conclusions In this first population-based study, to our knowledge, of SCA risk predictors among Hispanic or Latino adults, chronic kidney disease was the strongest risk factor for SCA, and established cardiovascular disease was also important. Early identification and management of chronic kidney disease may reduce SCA risk among Hispanic or Latino individuals, in addition to prevention and treatment of cardiovascular disease.

Evaluation of Sudden Cardiac Arrest by Race/Ethnicity Among Residents of Ventura County, California, 2015-2020

IMPORTANCE

Sudden cardiac arrest (SCA) is a major public health problem. Owing to a lack of population-based studies in multiracial/multiethnic communities, little information is available regarding race/ethnicity-specific epidemiologic factors of SCA.

OBJECTIVE

To evaluate the association of race/ethnicity with burden, outcomes, and clinical profile of individuals experiencing SCA.

DESIGN, SETTING, AND PARTICIPANTS

A 5-year prospective, population-based cohort study of out-of-hospital SCA was conducted from February 1, 2015, to January 31, 2020, among residents of Ventura County, California (2018 population, 848 112: non-Hispanic White [White], 45.8%; Hispanic/Latino [Hispanic], 42.4%; Asian, 7.3%; and Black, 1.7% individuals). All individuals with out-of-hospital SCA of likely cardiac cause and resuscitation attempted by emergency medical services were included.

EXPOSURES

Data on circumstances and outcomes of SCA from prehospital emergency medical services records and data on demographics and pre-SCA clinical history from detailed archived medical records, death certificates, and autopsies.

MAIN OUTCOMES AND MEASURES

Annual age-adjusted SCA incidence by race and ethnicity and SCA circumstances and outcomes by ethnicity. Clinical profile (cardiovascular risk factors, comorbidity burden, and cardiac history) by ethnicity, overall, and stratified by sex.

RESULTS

A total of 1624 patients with SCA were identified (1059 [65.2%] men; mean [SD] age, 70.9 [16.1] years). Race/ethnicity data were available for 1542 (95.0%) individuals, of whom 1022 (66.3%) were White, 381 (24.7%) were Hispanic, 86 (5.6%) were Asian, 31 (2.0%) were Black, and 22 (1.4%) were other race/ethnicity. Annual age-adjusted SCA rates per 100 000 residents of Ventura County were similar in White (37.5; 95% CI, 35.2-39.9), Hispanic (37.6; 95% CI, 33.7-41.5; P = .97 vs White), and Black (48.0; 95% CI, 30.8-65.2; P = .18 vs White) individuals, and lower in the Asian population (25.5; 95% CI, 20.1-30.9; P = .006 vs White). Survival to hospital discharge following SCA was similar in the Asian (11.8%), Hispanic (13.9%), and non-Hispanic White (13.0%) (P = .69) populations. Compared with White individuals, Hispanic and Asian individuals were more likely to have hypertension (White, 614 [76.3%]; Hispanic, 239 [79.1%]; Asian, 57 [89.1%]), diabetes (White, 287 [35.7%]; Hispanic, 178 [58.9%]; Asian, 37 [57.8%]), and chronic kidney disease (White, 231 [29.0%]; Hispanic, 123 [40.7%]; Asian, 33 [51.6%]) before SCA. Hispanic individuals were also more likely than White individuals to have hyperlipidemia (White, 380 [47.2%]; Hispanic, 165 [54.6%]) and history of stroke (White, 107 [13.3%]; Hispanic, 55 [18.2%]), but less likely to have a history of atrial fibrillation (White, 251 [31.2%]; Hispanic, 59 [19.5%]).

CONCLUSIONS AND RELEVANCE

The results of this study suggest that the burden of SCA was similar in Hispanic and White individuals and lower in Asian individuals. The Asian and Hispanic populations had shared SCA risk factors, which were different from those of the White population. These findings underscore the need for an improved understanding of race/ethnicity-specific differences in SCA risk.

Prevalence of Abnormal Heart Weight After Sudden Death in People Younger than 40 Years of Age

Background After sudden cardiac death in people aged <40 years, heart weight is a surrogate for cardiomegaly and a marker for cardiomyopathy. However, thresholds for cardiomegaly based on heart weight have not been validated in a cohort of cases of sudden cardiac death in young people. Methods and Results We surveyed medical examiner offices to determine which tools were used to assess heart weight norms. The survey determined that there was no gold standard for cardiomegaly (52 centers reported 22 different methods). We used a collection of heart weight data from sudden deaths in the Northwestern Sudden Death Collaboration (NSDC) to test the 22 methods. We found that the methods reported in our survey had little consistency: they classified between 18% and 81% of NSDC hearts with cardiomegaly. Therefore, we obtained biometric and postmortem data from a reference population of 3398 decedents aged <40 years. The reference population was ethnically diverse and had no known cardiac pathology on autopsy or histology. We derived and validated a multivariable regression model to predict normal heart weights and a threshold for cardiomegaly (upper 95% CI limit) in the young reference population (the Chicago model). Using the new model, the prevalence of cardiomegaly in hearts from the NSDC was 19%. Conclusions Medical examiner offices use a variety of tools to classify cardiomegaly. These approaches produce inconsistent results, and many overinterpret cardiomegaly. We recommend the model proposed to classify postmortem cardiomegaly in cases of sudden cardiac death in young people.

Bringing Critical Race Praxis Into the Study of Electrophysiological Substrate of Sudden Cardiac Death: The ARIC Study

Background Race is an established risk factor for sudden cardiac death (SCD). We sought to determine whether the association of electrophysiological substrate with SCD varies between black and white individuals. Methods and Results Participants from the ARIC (Atherosclerosis Risk in Communities) study with analyzable ECGs (n=14 408; age, 54±6 years; 74% white) were included. Electrophysiological substrate was characterized by ECG metrics. Two competing outcomes were adjudicated: SCD and non-SCD. Interaction of ECG metrics with race was studied in Cox proportional hazards and Fine-Gray competing risk models, adjusted for prevalent cardiovascular disease, risk factors, and incident nonfatal cardiovascular disease. At the baseline visit, adjusted for age, sex, and study center, blacks had larger spatial ventricular gradient magnitude (0.30 mV; 95% CI, 0.25-0.34 mV), sum absolute QRST integral (18.4 mV*ms; 95% CI, 13.7-23.0 mV*ms), and Cornell voltage (0.30 mV; 95% CI, 0.25-0.35 mV) than whites. Over a median follow-up of 24.4 years, SCD incidence was higher in blacks (2.86 per 1000 person-years; 95% CI, 2.50-3.28 per 1000 person-years) than whites (1.37 per 1000 person-years; 95% CI, 1.22-1.53 per 1000 person-years). Blacks with hypertension had the highest rate of SCD: 4.26 (95% CI, 3.66-4.96) per 1000 person-years. Race did not modify an association of ECG variables with SCD, except QRS-T angle. Spatial QRS-T angle was associated with SCD in whites (hazard ratio, 1.38; 95% CI, 1.25-1.53) and hypertension-free blacks (hazard ratio, 1.52; 95% CI, 1.09-2.12), but not in blacks with hypertension (hazard ratio, 1.15; 95% CI, 0.99-1.32) (P-interaction=0.004). Conclusions Race did not modify associations of electrophysiological substrate with SCD and non-SCD. Electrophysiological substrate does not explain racial disparities in SCD rate.

Videos to reduce racial disparities in ICD therapy Via Innovative Designs (VIVID) trial: Rational, design and methodology

BACKGROUND

Despite a higher prevalence of sudden cardiac death (SCD), black individuals are less likely than whites to have an implantable cardioverter defibrillator (ICD) implanted. Racial differences in ICD utilization is in part explained by higher refusal rates in black individuals. Decision support can assist with treatment-related uncertainty and prepare patients to make well-informed decisions.

METHODS

The Videos to reduce racial disparities in ICD therapy Via Innovative Designs (VIVID) study will randomize 350 black individuals with a primary prevention indication for an ICD to a racially concordant/discordant video-based decision support tool or usual care. The composite primary outcome is (1) the decision for ICD placement in the combined video groups compared with usual care and (2) the decision for ICD placement in the racially concordant relative to discordant video group. Additional outcomes include knowledge of ICD therapy and SCD risk; decisional conflict; ICD receipt at 90 days; and a qualitative assessment of ICD decision making in acceptors, decliners, and those undecided.

CONCLUSIONS

In addition to assessing the efficacy of decision support on ICD acceptance among black individuals, VIVID will provide insight into the role of racial concordance in medical decision making. Given the similarities in the root causes of racial/ethnic disparities in care across health disciplines, our approach and findings may be generalizable to decision making in other health care settings.

Sudden cardiac death in the Kazakh and Han peoples of Xinjiang, China: A comparative cross-sectional study

Sudden cardiac death (SCD) is a major cause of mortality in China. This study collected reference data for future programs of prevention of SCD among the ethnic Kazakh and Han populations in Xinjiang, China.From January 1, 2015 to December 31, 2015, 2 monitoring locations in northern Xinjiang China were utilized. These locations were selected based on the geographic, economic, and administrative structures of the ethnic Kazakh settlements in Xinjiang. Investigators were trained to investigate SCDs in Kazakh and Han people, a study population totaling more than 400,000. The populations were compared for SCD incidence.The average age of the Han population was significantly higher than that of the Kazakh. During the year 2015, there were 135 SCDs, specifically 67 and 68 in the Han and Kazakh populations, respectively, incidences of 37.94 and 36.2 per 100,000. After standardizing for age, the incidence in these populations was 29.36 and 51.85 per 100,000. Among those who experienced SCD, the prevalence of hypertension was higher in the Kazakh group than in the Han. The multivariate analysis of populations with SCD showed that, among the patients with coronary heart disease, the Kazakh were more likely to have SCD than the Han (odds ratio: 3.58, confidence interval: 1.18-10.95).Among the elderly, the incidence of SCD was much higher in the Kazakh population than in the Han population. Basic medical services and health education should be strengthened in the Kazakh pastoral areas.

Epidemiological investigation of sudden cardiac death in multiethnic Xinjiang Uyghur autonomous region in Northwest China

BACKGROUND

The epidemiological characteristics of sudden cardiac death (SCD) in the autonomous region of Xinjiang Uygur have been largely unknown. This study aimed to evaluate the incidence and demographic risk factors of SCD in Xinjiang, China.

METHODS

This retrospective study reviewed medical records from 11 regions in Xinjiang with different geography (north and south of the Tian Shan mountain range), gross domestic product, and ethnicity (Han, Uyghur, Kazakh, and Hui). SCD was defined as unexpected death due to cardiac reasons within 1 hour after the onset of acute symptoms, including sudden death, unexpected death, and nonviolent death. Monitoring was conducted throughout 2015. Demographic and mortality data were recorded and age-adjusted standardized risk ratio (SRR) was analyzed.

RESULTS

Among 3,224,103 residents, there were 13,308 all-cause deaths and 1244 events of SCD (784 men and 460 women; overall incidence 38.6 per 100,000 residents). SCD was associated with age (χ2 = 2105.3), but not geography. Men had an increased risk of SCD compared with women (SRR: 1.75, 95% CI: 1.10-2.79). The risk of SCD was highest in residents of the Uyghur (SRR: 1.59, 95% CI: 1.05-2.42) and Kazakh (SRR: 1.92, 95% CI: 1.29-2.87) compared with those of the Han. Poor economic development was associated with elevated risk of SCD (SRR: 1.55, 95% CI: 1.02-2.38).

CONCLUSION

SCD is an important public health issue in China. Our understanding of the demographic differences on SCD in Xinjiang, China may improve the risk stratification and management to reduce the incidence and lethality of SCD.

Associations between common ion channel single nucleotide polymorphisms and sudden cardiac death in adults: A MOOSE-compliant meta-analysis

BACKGROUND

We sought to identify common ion channel single nucleotide polymorphisms (SNPs) associated with the occurrence of sudden cardiac death (SCD) to predict the incidence of SCD in clinical settings.

METHODS

This study involved a systematic review and meta-analysis of ion channel SNPs and risk of SCD in adults. We searched public databases for studies published up to September 19, 2017. We examined relationships between SNPs in common ion channel genes and the incidence of SCD.

RESULTS

We collected data for 22 trials that included a total of 4149 patients who experienced SCD or had a high risk of SCD and assessed these data in our meta-analysis. An allelic model showed that rs11720524 in SCN5A clearly protected against SCD (odds ratio [OR]: 0.76; 95% confidence interval [95% CI]: 0.67-0.85; P < .001). Subgroup analysis showed that rs11720524 in SCN5A protected against SCD in Europeans and Caucasians but not in Koreans. The allelic model indicated that rs12296050 in KCNQ1 also had significant protective effects against SCD (OR: 0.85; 95% CI: 0.76-0.96; P = .007). Moreover, this model demonstrated that rs2283222 in KCNQ1 had a significant negative relationship with SCD (OR: 0.73; 95% CI: 0.62-0.85; P < .001). Rs12296050 in KCNQ1 protected against SCD in Koreans and Americans. Our results also showed that rs790896 in RYR2 was negatively associated with SCD in a dominant model (OR: 0.66; 95% CI: 0.45-0.97; P = .033).

CONCLUSIONS

Rs11720524 in SCN5A is negatively related to SCD in Europeans and Caucasians, and rs12296050 and rs2283222 in KCNQ1 and rs790896 in RYR2 clearly have protective effects against SCD.

Critical Roles of Xirp Proteins in Cardiac Conduction and Their Rare Variants Identified in Sudden Unexplained Nocturnal Death Syndrome and Brugada Syndrome in Chinese Han Population

BACKGROUND

Sudden unexplained nocturnal death syndrome (SUNDS) remains an autopsy negative entity with unclear etiology. Arrhythmia has been implicated in SUNDS. Mutations/deficiencies in intercalated disc components have been shown to cause arrhythmias. Human cardiomyopathy-associated 1 (XIRP1) and 3 (XIRP2) are intercalated disc-associated, Xin repeats-containing proteins. Mouse Xirp1 is necessary for the integrity of intercalated disc and for the surface expression of transient outward and delayed rectifier K+ channels, whereas mouse Xirp2 is required for Xirp1 intercalated disc localization. Thus, XIRP1 and XIRP2 may be potentially causal genes for SUNDS.

METHODS AND RESULTS

We genetically screened XIRP genes in 134 sporadic SUNDS victims and 22 Brugada syndrome (BrS) cases in a Chinese Han population. We identified 16 rare variants (6 were in silico predicted as deleterious) in SUNDS victims, including a novel variant, XIRP2-E215K. There were also four rare variants (2 were in silico predicted as deleterious) detected in BrS cases, including a novel variant, XIRP2-L2718P. Interestingly, among these 20 variants, we detected 2 likely pathogenic variants: a nonsense variant (XIRP2-Q2875*) and a frameshift variant (XIRP2-T2238QfsX7). Analyzing available Xirp2 knockout mice, we further found that mouse hearts without Xirp2 exhibited prolonged PR and QT intervals, slow conduction velocity, atrioventricular conduction block, and an abnormal infranodal ventricular conduction system. Whole-cell patch-clamp detected altered ionic currents in Xirp2-/- cardiomyocytes, consistent with the observed association between Xirp2 and Nav1.5/Kv1.5 in co-immunoprecipitation.

CONCLUSIONS

This is the first report identifying likely pathogenic XIRP rare variants in arrhythmogenic disorders such as SUNDS and Brugada syndrome, and showing critical roles of Xirp2 in cardiac conduction.

Ethnic Differences in Genetic Ion Channelopathies Associated with Sudden Cardiac Death: A Systematic Review and Meta-Analysis

BACKGROUND AND AIMS

Reports of allele frequencies encoding ion channel, or their interacting proteins associated with sudden cardiac death among different ethnic groups have been inconsistent. Here, we aimed to characterize the distribution of these genes and their alleles among various ethnicities through meta-analysis.

METHODS

We conducted a systematic review and meta-analysis to assess the mean allele frequencies of channelopathy genes SCN5A, NOS1AP, KCNH2, KCNE1, and KCNQ1 among the Black, Caucasian, Asian, and Hispanic ethnicities. Searches in PubMed, Google Scholar, and Web of Science resulted in 18 reports published before July 2015 that met the eligible criteria. Allele frequencies were averaged by weight, and pooled values were calculated by inverse variance. Fixed-effects and random-effects models were used to pool effect sizes within each study and across different studies, respectively. Moreover, to extend our findings, we used sequenced genomic data from the Exome Aggregation Consortium to compare allele frequencies between different ethnicities.

RESULTS

Meta-analysis of published studies supports that Asians had the highest overall mean allele frequencies of NOS1AP (0.36%, 95% CI: 0.30, 0.43; P<0.001), and SCN5A frequencies (0.17%, 95% CI: 0.07, 0.27, P=0.001), and whereas Caucasians had the highest KCNH2 frequency (0.21%, 95% CI: 0.16, 0.25; P<0.001), and Hispanics the highest KCNQ1 frequency (0.16%). Analysis of the Exome Aggregation Consortium also provided consistent data in agreement the meta-analysis.

CONCLUSION

Overall, Asians carried the most alleles of genes associated with sudden cardiac death. The meta-analysis reveals significant differences in allele distribution of channelopathy-associated genes among different ethnic groups.

Comparison of QRS Duration and Associated Cardiovascular Events in American Indian Men Versus Women (The Strong Heart Study)

Electrocardiographic QRS duration at rest is associated with sudden cardiac death and death from coronary heart disease in the general population. However, its relation to cardiovascular events in American Indians, a population with persistently high cardiovascular disease mortality, is unknown. The relation of QRS duration to incident cardiovascular disease during 17.2 years of follow-up was assessed in 1,851 male and female Strong Heart Study participants aged 45 to 74 years without known cardiovascular disease at baseline. Cox regression with robust standard error estimates was used to determine the association between quintiles of QRS duration and incident cardiovascular disease in gender-stratified analyses, adjusted for age, systolic blood pressure, hypertension, antihypertensive medication use, body mass index, current smoking, diabetes, total cholesterol, high-density lipoprotein cholesterol, and albuminuria. In women only, QRS duration in the highest quintile (≥105 ms) conferred significantly higher risk of cardiovascular disease than QRS duration in the lowest quintile (64 to 84 ms) (hazard ratio 1.6, 95% CI 1.1 to 2.4) likely because of higher risks of coronary heart disease (hazard ratio 1.8, 95% CI 1.1 to 3.1) and myocardial infarction (hazard ratio 2.1, 95% CI 1.0 to 4.7). Furthermore, when added to the Strong Heart Study Coronary Heart Disease Risk Calculator, QRS duration significantly improved prediction of future coronary heart disease events in women (Net Reclassification Index 0.17, 95% CI 0.06 to 0.47). In conclusion, QRS duration is an independent predictor of cardiovascular disease in women in the Strong Heart Study cohort and may have value in estimating risk in populations with similar risk profiles and a high lifetime incidence of cardiovascular disease.

Long-Term Prognosis of Patients with an Implantable Cardioverter-Defibrillator in Korea

PURPOSE

The objective of this study was to elucidate the long-term prognosis of patients with implantable cardioverter-defibrillators (ICDs) in Korea.

MATERIALS AND METHODS

We enrolled 405 patients (age, 57.7±16.7 years; 311 men) who had undergone ICD implantation. The patients were divided into three groups: heart failure (HF) and ICD for primary (group 1, n=118) and secondary prevention (group 2, n=93) and non-HF (group 3, n=194). We compared appropriate and inappropriate ICD therapy delivery among the groups and between high- (heart rate ≥200 /min) and low-rate (<200 /min) ICD therapy zones.

RESULTS

During the follow-up period (58.9±49.8 months), the annual appropriate ICD therapy rate was higher in group 2 (10.4%) than in groups 1 and 3 (6.1% and 5.9%, respectively, p<0.001). There were no significant differences in annual inappropriate ICD therapy rate among the three groups. In group 1, the annual appropriate ICD therapy rate was significantly lower in patients with a high-rate versus a low-rate therapy zone (4.5% and 9.6%, respectively, p=0.026). In group 3, the annual inappropriate ICD therapy rate was significantly lower in patients with a high-rate versus a low-rate therapy zone (3.1% and 4.0%, respectively, p=0.048).

CONCLUSION

Appropriate ICD therapy rates are not low in Korean patients with ICD, relative to prior large-scale studies in Western countries. Appropriate and inappropriate ICD therapy could be reduced by a high-rate therapy zone in patients with HF and ICD for primary prevention, as well as non-HF patients, respectively.

Referral Patterns for Primary Prophylaxis Implantable Cardioverter Defibrillator Therapy for an Urban US Population

Implantable cardioverter defibrillators (ICDs) have been demonstrated to improve survival for both primary and secondary prevention of sudden cardiac arrest. However, studies suggest that ICD therapy is underused in appropriate candidates. Sex and racial disparities in ICD use have been suggested. We sought to characterize the referral patterns of high-risk patients for the primary prophylaxis of sudden cardiac arrest at a tertiary academic medical center serving a diverse population in an urban US setting. Electronic hospital databases were retrospective reviewed for patients meeting criteria for prophylactic ICD implantation. We evaluated the association of gender, age, race, and primary language with the referral and subsequent implantation of an ICD. We identified 1,055 patients satisfying prophylactic ICD criteria: 600 men, mean age 62.6 years, 27.6% black, 19.3% white, 23.3% Hispanic, and 49.8% primary language of English. Of the 673 patients (63.7%) referred for ICD evaluation, 345 underwent implantation, 125 declined, and 203 had significant co-morbidities that precluded implantation. Gender, race, and primary language were not associated with referral for ICD or with decision to proceed with implantation. Patients of increased age were less likely to be referred for ICD and were more likely to refuse implantation. ICD therapy was not considered in 146 patients eligible for prophylactic implantation. In conclusion, referral rates for ICD consideration were higher at our institution than in previous reports. Nonetheless, 14% of appropriate patients were not considered. This argues for the importance of increased education for patients and referring physicians.

Ethnic differences among implantable cardioverter defibrillators recipients in Israel

Heart failure is an increasingly common condition arising from a variety of different pathophysiological processes. Little is known about the unique features of Israeli Arabs who present with heart failure and who undergo cardiac device implantation. The study population comprised of 4,671 patients who were enrolled in the national Israeli Implantable Cardioverter Defibrillator registry. We compared demographic, clinical, and echocardiographic characteristics; device-related indications; and outcomes between Israeli Arabs (n = 733) and Jews (n = 3,938), who were enrolled in the registry from July 2010 through December 2013. Israeli Arabs constituted 15.7% of the study population. They were younger at presentation compared with Jews (57 ± 15 vs 66 ± 12 years, respectively; p <0.001), with a greater burden of co-morbidities, including diabetes mellitus and chronic obstructive lung disease and smoking. In addition, Arab patients had a greater frequency of non-ischemic cardiomyopathy (40.2% vs 24.6%, respectively; p <0.001), which was associated with a greater frequency of familial history of sudden cardiac death. During 15 ± 9 month follow-up, the mortality rates and appropriate device therapy were similar in both ethnic groups. In conclusion, Israeli Arab patients implanted with implantable cardioverter defibrillators display unique clinical features with greater prevalence of non-ischemic cardiomyopathy characterized by an early-onset and rapid deterioration.

Rationale and design of the Pan-African Sudden Cardiac Death survey: the Pan-African SCD study

BACKGROUND

The estimated rate of sudden cardiac death (SCD) in Western countries ranges from 300,000 to 400,000 annually, which represents 0.36 to 1.28 per 1 000 inhabitants in Europe and the United States. The burden of SCD in Africa is unknown. Our aim is to assess the epidemiology of SCD in Africa.

METHODS

The Pan-Africa SCD study is a prospective, multicentre, community-based registry monitoring all cases of cardiac arrest occurring in victims over 15 years old. We will use the definition of SCD as 'witnessed natural death occurring within one hour of the onset of symptoms' or 'unwitnessed natural death within 24 hours of the onset of symptoms'. After approval from institutional boards, we will record demographic, clinical, electrocardiographic and biological variables of SCD victims (including survivors of cardiac arrest) in several African cities. All deaths occurring in residents of districts of interest will be checked for past medical history, circumstances of death, and autopsy report (if possible). We will also analyse the employment of resuscitation attempts during the time frame of sudden cardiac arrest (SCA) in various patient populations throughout African countries.

CONCLUSION

This study will provide comprehensive, contemporary data on the epidemiology of SCD in Africa and will help in the development of strategies to prevent and manage cardiac arrest in this region of the world.

Prevalence and significance of early repolarisation in a black African population: data of 246 individuals with cardiovascular morbidity

BACKGROUND

Early repolarisation (ER) is commonly seen on electrocardiograms (ECG). Recent reports have described the relationship between ER and sudden cardiac death (SCD). The prevalence and significance of ER have not been studied in black Africans.

METHOD

We matched clinical and ECG records of subjects over 18 years of age who consulted a cardiac unit in two medical centres of Douala, Cameroon. A questionnaire focusing on past history of syncope or family history of sudden unexplained death (SUD) was filled in by each subject. A 12-lead ECG was recorded by a trained nurse and analysed by two independent physicians.

RESULTS

Of the 752 ECGs recorded, we studied 246 index cases. The mean age of subjects was 45 ± 16 years and 53% were female. Almost 57% had hypertension, 41% had palpitations and 18% reported a history of syncope. ER pattern was found in 20% [slurring in three (3%), notching in 13% and both in three (7%)]. ER subjects were younger than those without (41 ± 16 vs 49 ± 16 years, p = 0.0048). Lead localisation was predominantly the laterals for the slurring pattern, whereas the inferior and lateral leads were equally involved for the notching pattern. Negative T waves in the infero-lateral leads were associated with ER (p = 0.00025). Among the subjects with syncope, 41% displayed ER and 13% did not have ER (p = 0.00014). The notching pattern seemed to be associated with syncope (p = 0.00011).

CONCLUSION

Early repolarisation is frequent in black Africans, especially in the setting of cardiovascular morbidity. Early repolarisation may be associated with a past history of syncope, especially the notched pattern.

Educational videos to reduce racial disparities in ICD therapy via innovative designs (VIVID): a randomized clinical trial

BACKGROUND

Black individuals eligible for an implantable cardioverter/defibrillator (ICD) are considerably less likely than white individuals to receive one. This disparity may, in part, be explained by racial differences in patient preferences. We hypothesized that a targeted patient-centered educational video could improve knowledge of sudden cardiac arrest (SCA) and ICDs and reduce racial differences in ICD preferences. We conducted a pilot study to assess the feasibility of testing this hypothesis in a randomized trial.

METHODS

We created a video that included animation, physician commentary, and patient testimonials on SCA and ICDs. The primary outcome was the decision to have an ICD implanted as a function of race and intervention. Between January 1, 2011, and December 31, 2011, 59 patients (37 white and 22 black) were randomized to the video or health care provider counseling/usual care.

RESULTS

Relative to white patients, black patients were younger (median age, 55 vs 68 years) and more likely to have attended college or technical school. Baseline SCA and ICD knowledge was similar and improved significantly in both racial groups after the intervention. Black patients viewing the video were as likely as white patients to want an ICD (60.0% vs 79.2%, P = .20); and among those in the usual care arm, black patients were less likely than white patients to want an ICD (42.9% vs 84.6% P = .05).

CONCLUSION

Among individuals eligible for an ICD, a video decision aid increased patient knowledge and reduced racial differences in patient preference for an ICD.

Characteristics of sudden arrhythmic death in a diverse, urban community

BACKGROUND

Sudden cardiac death (SCD) remains a major public health problem; however, its true burden remains unknown with widely variable estimates of its incidence. We aimed to examine the contemporary epidemiology and autopsy characteristics of SCD in an ethnically diverse community.

METHODS

Three physicians reviewed all deaths of individuals aged ≥20 years reported to the San Francisco medical examiner in 2007 for presentations fitting World Health Organization (WHO) SCD criteria-within 1 hour of symptom onset (witnessed) or within 24 hours of being observed alive and symptom free (unwitnessed). After comprehensive review of medical examiner investigation, WHO SCDs were classified as sudden arrhythmic death (SAD) or nonarrhythmic death. Coronary artery disease (CAD) and cardiac mass were evaluated in all SADs undergoing autopsy and compared with demographically similar accidental trauma control deaths.

RESULTS

We identified 252 WHO SCDs; 145 were SADs. Men had a 2.2-fold higher SAD rate (P < .0005). Blacks had a 3.15-fold higher SAD rate compared with whites (P = .003). Significant CAD was present in 38.9% of SADs and associated with higher SAD risk compared with control deaths (OR 2.58, 95% CI 1.12-5.97, P = .026). Mean cardiac mass was linearly associated with risk for SAD in cases without significant CAD (OR 2.06 per 100 g, 95% CI 1.43-2.98, P < .0005).

CONCLUSIONS

In a diverse, urban population, SAD incidence varied substantially by gender and race. Significant CAD accounted for far fewer SADs than previous studies but remained associated with a 2.6-fold higher risk as compared with control deaths. These findings may reflect the evolving contemporary epidemiology of SCD.

Sudden death after pediatric heart transplantation: analysis of data from the Pediatric Heart Transplant Study Group

BACKGROUND

Sudden death is a well-recognized complication of heart transplantation. Little is known about the incidence and risk factors for sudden death after transplant in children. The purpose of this study was to determine the incidence of and risk factors for sudden death.

METHODS

This retrospective multicenter cohort study used the Pediatric Heart Transplant Study Group (PHTS) database, an event-driven registry of children aged <18 at listing undergoing heart transplantation between 1993 and 2007. Standard Kaplan-Meier and parametric analyses were used for survival analysis. Multivariate analysis in the hazard-function domain was used to identify risk factors for sudden death after transplant.

RESULTS

Of 604 deaths in 2,491 children who underwent heart transplantation, 94 (16%) were classified as sudden. Freedom from sudden death was 97% at 5 years, and the hazard for sudden death remained constant over time at 0.01 deaths/year. Multivariate risk factors associated with sudden death included black race (hazard ratio [HR], 2.6; p < 0.0001), United Network of Organ Sharing (UNOS) status 2 at transplant (HR, 1.8; p = 0.008), older age (HR, 1.4/10 years of age; p = 0.03), and an increased number of rejection episodes in the first post-transplant year (HR, 1.6/episode; p = 0.03).

CONCLUSION

Sudden death accounts for 1 in 6 deaths after heart transplant in children. Older recipient age, recurrent rejection within the first year, black race, and UNOS status 2 at listing were associated with sudden death. Patients with 1 or more of these risk factors may benefit from primary prevention efforts.

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.

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.

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.

Pattern of inheritance in three sudden unexplained death syndrome ("Lai-tai") families

Sudden Unexplained Death Syndrome (SUDS) (or Lai-tai) is sudden death in previously healthy young adults without any structural cause of death from autopsy findings. Our previous data showed that familial SUDS is not X-linked recessive. The objective of this study was to determine the pattern of inheritance in familial SUDS using the ECG markers of Brugada syndrome (RBBB and ST-segment elevation in V1 to V3), SUDS and presumptive SUDS as phenotypes. We employed the standard 12-lead ECG and higher intercostal space (ICS) V1 to V3 (-V1 to -V3 and -2V1 to -2V3) leads ECG in SUDS relatives after procainamide and drew the pedigree. We studied 62 relatives of 9 SUDS victims who died in Singapore and selected 3 families (n = 34) for the procainamide test and ECG. The mean age was 36.4 +/- 23.6 years (4-78 years). Three SUDS families showed the same pattern of inheritance of autosomal dominant.

The Brugada syndrome: a recently recognised genetic disease causing sudden cardiac death

Australian doctors need to be aware of this little-known syndrome, which is a cause of sudden cardiac death. It is more common among Southeast Asian people, who make up a considerable proportion of our population. We report two cases which represent very different clinical presentations of this condition.

Enrollment of sudden cardiac death victims into a limited cardiac autopsy study in the emergency department

The lack of balanced recruitment for racial and ethnic groups in research protocols is an important ethical issue. African Americans have a history of forced participation, unethical research, and unwilling human dissection/demonstration that leads to a lack of participation in clinical research. We have embarked on a study of the pathophysiology of sudden death among African Americans which requires a limited autopsy of the heart. Our objective was to improve the recruitment rate in this study when compared with historical rates seen in clinical research and organ donation. We have screened 14 and enrolled 10 African Americans with sudden death (95% CI 0.41-0.91). By addressing the concerns of the African-American community and involving qualified input in the planning stages of the study we have been able to significantly improve the recruitment rate for this important population subgroup.

Ethnicity and long-term outcome after an acute coronary event. Multicenter Myocardial Ischemia Research Group

BACKGROUND

The role of ethnicity on the long-term outcome after myocardial infarction is not fully understood.

METHODS AND RESULTS

We analyzed the data from the Multicenter Study of Myocardial Ischemia in North America and Japan. We enrolled patients after acute myocardial infarction (MI) or unstable angina, with follow-up for 6 to 43 months, an average of 26 months. Among patients enrolled, there were 627 white, 158 black, and 109 Asian patients. Unadjusted cardiac events (cardiac death or nonfatal MI) were more frequent in black patients than in the other 2 ethnic groups (12% in blacks, 6. 4% in whites, 4.0% in Asians, P =.022). Although insulin-dependent diabetes, history of hypertension, and female sex were most frequent in black subjects, coronary angioplasty and thrombolysis at index event were done equally. After adjusting for several covariates, Cox analyses revealed that the black group was significantly associated with cardiac events (hazard ratio 6.5, P =.002). Subgroup analyses showed that the event rate among patients who had a higher educational level (6.1% in whites, 5.9% in blacks, and 7.0% in Asian, P =.94) or who were in a professional occupational class (5.7% in whites, 4.0% in blacks, and 4.8% in Asians, P = 1.0) was not different among the 3 ethnic groups.

CONCLUSIONS

Blacks have an increased rate of cardiac events after MI, and a lower socioeconomic status may contribute to the adverse outcome in this ethnic group.

Sudden cardiac death in Hispanic Americans and African Americans

OBJECTIVES

The goal of this study was to estimate rates of sudden cardiac death in US Hispanics and African Americans.

METHODS

Data on coronary deaths occurring outside of the hospital or in emergency rooms were examined for 1992.

RESULTS

In 1992, 53% (8194) of coronary heart disease deaths among Hispanic Americans 25 years of age and older occurred outside of the hospital or in emergency rooms. The percentage was lower among Hispanics than among non-Hispanic Whites and Blacks. Age-adjusted rates per 100,000 were lower in Hispanics than in non-Hispanic Whites or Blacks (Hispanic men, 75; White men, 166; Black men, 209; Hispanic women, 35; White women, 74; Black women, 108). The percentages dying outside of the hospital or in emergency rooms were higher in young persons, those living in nonurban areas, and those who were single.

CONCLUSIONS

The percentage and rate of coronary deaths occurring outside of the hospital or in emergency rooms were lower in Hispanics than in non-Hispanics; African Americans had the highest rates. Further research is needed on sudden coronary death in Hispanic Americans and African Americans.