BACKGROUND
Cardiac autonomic perturbations frequently antecede onset of paroxysmal atrial fibrillation (AF). Interventions that influence autonomic inputs to myocardium may prevent AF. However, whether low heart rate or heart rate variability (HRV), which are noninvasive measures of cardiac autonomic dysfunction, are associated with AF incidence is unclear.
OBJECTIVES
We sought to study the association between HRV and risk of AF.
METHODS
We studied 11,715 middle-aged adults in the ARIC (Atherosclerosis Risk in Communities) cohort with heart rate and HRV measures obtained from 2-min electrocardiogram (ECG) recordings performed at baseline (1987 to 1989). These measures included standard deviation of RR intervals (SDNN), high frequency (HF) (0.15 to 0.40 Hz), low frequency (LF) (0.04 to 0.15 Hz), and the LF/HF ratio (denoting a higher sympathetic to parasympathetic dominance). Incident AF cases were ascertained by ECG at ARIC follow-up visits, hospital discharge diagnosis, or death certificates through 2011.
RESULTS
During an average follow-up of 19.4 years, 1,580 or 13.5% of participants developed AF. A baseline heart rate <60 beats/min was modestly associated with increased AF risk. Lower overall HRV as well as increased sympathetic/parasympathetic tone were independently associated with higher risk of AF; the hazard ratio for each 1 SD lower SDNN was 1.14 (95% confidence interval [CI]: 1.08 to 1.21), for HF was 1.12 (95% CI: 1.06 to 1.17), and for LF/HF was 1.08 (95% CI: 1.03 to 1.14).
CONCLUSIONS
Cardiac autonomic dysfunction denoted by low resting short-term HRV was associated with higher AF incidence. Also, a low heart rate may be associated with higher AF risk. Further studies are needed to determine whether interventions in the general population to restore autonomic balance may prevent AF.