Carotid Intima‐Media Thickness and the Risk of Sudden Cardiac Death: The ARIC Study and the CHS

BACKGROUND: Sudden cardiac death (SCD) is associated with severe coronary heart disease in the great majority of cases. Whether carotid intima‐media thickness (C‐IMT), a known surrogate marker of subclinical atherosclerosis, is associated with risk of SCD in a general population remains unknown. The objective of this study was to investigate the association between C‐IMT and risk of SCD. METHODS AND RESULTS: We examined a total of 20 862 participants: 15 307 participants of the ARIC (Atherosclerosis Risk in Communities) study and 5555 participants of the CHS (Cardiovascular Health Study). C‐IMT and common carotid artery intima‐media thickness was measured at baseline by ultrasound. Presence of plaque was judged by trained readers. Over a median of 23.5 years of follow‐up, 569 participants had SCD (1.81 cases per 1000 person‐years) in the ARIC study. Mean C‐IMT and common carotid artery intima‐media thickness were associated with risk of SCD after adjustment for traditional risk factors and time‐varying adjustors: hazard ratios (HRs) with 95% CIs for fourth versus first quartile were 1.64 (1.15–2.63) and 1.49 (1.05–2.11), respectively. In CHS, 302 participants developed SCD (4.64 cases per 1000 person‐years) over 13.1 years. Maximum C‐IMT was associated with risk of SCD after adjustment: HR (95% CI) for fourth versus first quartile was 1.75 (1.22–2.51). Presence of plaque was associated with 35% increased risk of SCD: HR (95% CI) of 1.37 (1.13–1.67) in the ARIC study and 1.32 (1.04–1.68) in CHS. CONCLUSIONS: C‐IMT was associated with risk of SCD in 2 biracial community‐based cohorts. C‐IMT may be used as a marker of SCD risk and potentially to initiate early therapeutic interventions to mitigate the risk.