Available online 24 September 2022

Impaired atrial functional reserve during exercise may represent an early stage of atrial cardiomyopathy. To test this hypothesis, we evaluated left atrial (LA) and left ventricular (LV) function reserve during exercise in patients with paroxysmal atrial fibrillation (PAF).

Sixty-one patients with PAF undergoing radiofrequency catheter ablation and 38 healthy controls were prospectively enrolled. LV global longitudinal strain (GLS) and LA reservoir strain (LA-RS) were measured at rest and during supine bicycle exercise. To identify the early stage of atrial cardiomyopathy without LA structural remodeling, patients with PAF were divided into two groups according to LA volume index (LAVI): AF group 1 (LAVI ≥34 mL/m2) and AF group 2 (LAVI <34 mL/m2).

LV ejection fraction and GLS did not differ between patients with AF and controls. LAVI and LA-RS did not differ between AF group 2 and the controls. During exercise, LV-GLS improved in all groups. Increases in LA-RS were attenuated in both AF groups, which also exhibited lower LA functional reserve index (LAFRI) than the controls. Although resting LA-RS was similar between AF group 2 and the controls, LAFRI was significantly lower in AF group 2. LAFRI was associated with the risk of AF recurrence (hazard ratio: 0.852; 95% confidence interval: 0.736–0.988).

Atrial cardiomyopathy could be anticipated by impaired LA functional reserve during exercise in patients with AF, even in those with normal-sized LA. Atrial cardiomyopathy occurs independently of changes in LV function, and is associated with the recurrence of AF in patients with PAF after radiofrequency catheter ablation.

2022 Published by Elsevier Inc. on behalf of the American Society of Echocardiography.