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Racial Differences in Sudden Cardiac Death
Study Questions:
What is the lifetime incidence of sudden cardiac death (SCD) among blacks and whites? Are there risk factors that could account for racial disparities in cumulative risk of SCD?
Methods:
The study population was comprised of 15,069 (3,832 black) participants from the Atherosclerosis Risk in Communities Study (ARIC), a long-term community-based and multi-center cohort study of risk factors for coronary artery disease. SCD was defined as death from a sudden pulseless condition occurring out of hospital or in the emergency room from a cardiac cause in a previously stable individual. For witnessed cases, there had to be no noncardiac cause of the cardiac arrest. For unwitnessed cases, the patient must have been last known to be in a stable condition within 24 hours of the cardiac arrest. Expert physicians adjudicated cases with an interviewer agreement of 83.2%. Competing risk survival analysis modeling was used to determine cumulative incidence. Development of cardiovascular risk factors was collected at baseline and with each follow-up visit (median follow-up 27.4 years).
Results:
Overall, blacks were more likely to have hypertension, diabetes, elevated body mass index, left ventricular hypertrophy, lower educational level, and lack of insurance; 547 (215 black) participants had SCD. Cumulative incidence was highest in black men, followed by white men, black women, and white women. In sex-adjusted analysis, blacks had over 2 times the risk of SCD. The most important mediating factors accounting for the racial disparity were income (50.5% change in hazard ratio), hypertension, diabetes, education, and left ventricular hypertrophy. In subgroup analysis, the strongest association between race and SCD was in women and nonobese participants.
Conclusions:
In this cohort, blacks had a significantly higher risk for SCD than whites, more pronounced in women. The combination of socioeconomic and traditional cardiovascular risk factors accounted for approximately 65% of the increased risk in blacks.
Perspective:
Previous studies have shown that black patients have a higher risk of out-of-hospital sudden cardiac arrest and lower risk of survival from in-hospital sudden cardiac arrest. This study from ARIC investigators is the first to assess the influence of race and other risk factors on SCD cumulative risk in a large community-based cohort. Studies of SCD or sudden death or sudden unexpected death, especially with limited or no autopsy data, are often difficult to compare due to differing definitions, data ascertainment, and study population characteristics. The authors used a definition that included definitive and possible/probably sudden arrhythmic death and yet the agreement among experts was just 83.2%. One factor could be limited information on ARIC rates of life-threatening arrhythmias and information on resuscitation efforts; both are potential confounding factors that also have racial differences. Nevertheless, this large and robust cohort study emphasizes the urgent need for improved education, emergency preparedness, and preventative strategies to reduce the disproportionate incidence of SCD in black patients.
Clinical Topics: Arrhythmias and Clinical EP, Prevention, Atherosclerotic Disease (CAD/PAD), Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Hypertension
Keywords: African Continental Ancestry Group, Arrhythmias, Cardiac, Atherosclerosis, Body Mass Index, Coronary Artery Disease, Death, Sudden, Cardiac, Diabetes Mellitus, Emergency Service, Hospital, Hypertension, Hypertrophy, Left Ventricular, Out-of-Hospital Cardiac Arrest, Risk Factors, Secondary Prevention, Socioeconomic Factors
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