Ankle-Brachial Index and Risk of Sudden Cardiac Death in the Community: The ARIC Study

BACKGROUND: Sudden cardiac death (SCD) is a significant global public health problem accounting for 15% to 20% of all deaths. A great majority of SCD is associated with coronary heart disease, which may first be detected at autopsy. The ankle-brachial index (ABI) is a simple, noninvasive measure of subclinical atherosclerosis. The purpose of this study was to examine the relationship between ABI and SCD in a middle-aged biracial general population. METHODS AND RESULTS: Participants of the ARIC (Atherosclerosis Risk in Communities) study with an ABI measurement between 1987 and 1989 were included. ABI was categorized as low (<= 0.90), borderline (0.90-1.00), normal (1.00-1.40), and noncompressible (>1.40). SCD was defined as a sudden pulseless condition presumed to be caused by a ventricular tachyarrhythmia in a previously stable individual and was adjudicated by a committee of cardiac electrophysiologists, cardiologists, and internists. Cox proportional hazards models were used to evaluate the associations between baseline ABI and incident SCD. Of the 15 081 participants followed for a median of 23.5 years, 556 (3.7%) developed SCD (1.96 cases per 1000 person-years). Low and borderline ABIs were associated with an increased risk of SCD (demographically adjusted hazard ratios [HRs], 2.27 [95% CI, 1.64-3.14] and 1.52 [95% CI, 1.17-1.96], respectively) compared with normal ABI. The association between low ABI and SCD remained significant after adjustment for traditional cardiovascular risk factors (HR, 1.63 [95% CI, 1.15-2.32]). CONCLUSIONS: Low ABI is independently associated with an increased risk of SCD in a middle-aged biracial general population. ABI could be incorporated into future SCD risk prediction models.