The relationship between resting heart rate and peak VO₂: A comparison of atrial fibrillation and sinus rhythm

Resting heart rate is a surrogate marker associated with achieved exercise capacity, which has been observed in patients with sinus rhythm. The aim of this study was to examine and compare the relationships between resting heart rate and peak oxygen consumption in atrial fibrillation and sinus rhythm.

A total of 2160 consecutive patients undergoing cardiopulmonary exercise testing in our single-hospital cohort were divided into two groups according to rhythm status: an atrial fibrillation group (N = 320) and a sinus rhythm group (N = 1840). In the total cohort and sinus rhythm group, resting heart rate was negatively correlated with percentage of predicted peak oxygen consumption (P_trend < 0.0001); in atrial fibrillation patients, this correlation was apparently positive (P_trend = 0.032). Multivariate analysis of the total cohort showed a significant interaction between resting heart rate and rhythm status for peak oxygen consumption after adjustments for age, sex, ejection fraction, structural heart diseases and heart rate-lowering drugs. In the sinus rhythm group, resting heart rate was an independent, negative contributing factor for peak oxygen consumption, even after the adjustments for patient background. However, in the atrial fibrillation group, resting heart rate was a weak positive or non-independent contributing factor for peak oxygen consumption after the same adjustments.

The impact of resting heart rate on exercise capacity differed completely between atrial fibrillation and sinus rhythm, suggesting that heart rate control may need to be managed differently for atrial fibrillation and sinus rhythm, in light of exercise capacity that is related to quality of life and prognosis.