Abstract 9983: Low Heart Rate Variability and the Risk of Sudden Cardiac Death in the General Population: The Atherosclerosis Risk in Communities (ARIC) Study

Abstract

Background Low heart rate variability (HRV) is associated with an increased risk of sudden cardiac death (SCD) in post-myocardial infarction and heart failure patients. However, it is unclear whether low HRV is associated with an increased risk of SCD in the general population. We sought to determine whether low HRV predicts risk of SCD in the ARIC study, a large US population-based cohort study.

Methods We included 14,071 subjects (aged 45-64 years, 55% female, 27% black) enrolled 1987-89, and followed through 2001. Measures of HRV (RR interval, standard deviation of all normal RR intervals [SDNN], root mean square of successive differences [r-MSSD], low frequency power [LF], and high frequency power [HF]) were obtained from 2-minute rhythm strips at baseline. SCD was physician-adjudicated and was defined as death from a sudden, pulseless condition from a cardiac origin in a previously stable individual. We used Cox proportional hazards models to assess association between HRV measures and SCD. We also assessed interactions by sex and race.

Results During follow-up (median 13.0 yrs), there were 264 SCD cases. Compared with the lowest tertile, the highest tertile of RR, SDNN, and LF were significantly associated with a lower risk of SCD (Table 1). Greater r-MSSD and HF were also non-significantly associated with a lower risk of SCD. In addition, there was an interaction between SDNN and sex (P for interaction=0.004): Hazard ratios (95% CI) of SCD in the highest tertile compared with the lowest tertile in women and men were 0.41 (0.21-0.80), P=0.009 and 0.96 (0.66-1.40), P=0.83, respectively. We did not find an interaction by race.

Conclusions Low HRV is associated with an increased risk of SCD in the general population. Before low HRV can be used as a marker for the risk stratification of SCD in the general population, additional studies to validate this novel association and to define the role of HRV in risk stratification of SCD in the general population are warranted.