Low Heart Rates Predict Incident Atrial Fibrillation in Healthy Middle-Aged Men

CIRCEP: July 21, 2013

Background—Low resting heart rate (HR) has been associated with atrial fibrillation (AF) in athletes. We aimed to study if low HR at rest or during exercise testing was a predictor of AF in initially healthy middle-aged men.

Methods and Results—A total of 2014 healthy Norwegian men participated in a prospective cardiovascular survey including a standardized bicycle exercise test in 1972-1975. During up to 35 years follow-up (53.000 person-years of observation) 270 men developed incident AF, documented by scrutiny of health charts in all Norwegian hospitals. Risk estimation was analyzed with Cox proportional hazard models. Low exercise HR after 6 min exercise on the moderate workload 100W (HR100W) was a predictor of incident AF. Men with HR100W <100 bpm (n=260) were characterized by high physical fitness, low resting and low maximum HR, and they had 1.60-fold AF risk (95% CI, 1.11 to 2.26) compared to men with HR100W ≥100 bpm when adjusted for age, systolic blood pressure (BP) and physical fitness. Additional adjustment for relative heart volume slightly reduced the association. The subgroup of men (n=860) with hypertensive BP measurements at baseline had the highest risk with hazard ratio 2.08 (1.19 to 3.45). Read more