Impact of exercise capacity on the long-term incidence of atrial arrhythmias in heart failure.

We sought to demonstrate the impact of improved peak exercise oxygen consumption (V̇O2) during maximal exercise testing after cardiac rehabilitation (CR) on the incidence of arrhythmias in patients with heart failure (HF). The present study comprised of 220 patients with HF, and peak V̇O2 was examined at 2 and 5 months after CR. Of the 220 patients, 110 (50%) had a low peak V̇O2 of < 14 mL/min/kg at 2 months. The peak V̇O2 improved in 86 of these 110 (78%) patients at 5 months after CR. During a median follow-up of 6 years, the patients with improvement in peak V̇O2, compared to those without peak V̇O2 improvement, had a lower rate of mortality (4% vs. 29%, log-rank, P < 0.001) and HF hospitalization (6 vs. 17%, log-rank, P = 0.044) and a lower incidence of new-onset atrial arrhythmias (9 vs. 27%, log-rank, P = 0.013), with no difference in the incidence of ventricular arrhythmias between groups (1 vs. 4%, log-rank, P = 0.309). The majority of deaths in the patients without an improved peak V̇O2 were because of cardiovascular events (73%), particularly progressive HF (55%). Early detection and management of atrial arrhythmias may improve outcomes in patients without peak V̇O2 improvement after CR.