Association of Myocardial Degeneration With Delayed Recovery of Left Ventricular Function in Atrial Fibrillation-Induced Cardiomyopathy

Abstract

Background: Atrial fibrillation-induced cardiomyopathy (AF-CM) is a secondary cardiomyopathy characterized by recovery of left ventricular (LV) dysfunction after restoration of sinus rhythm from atrial fibrillation (AF); however, the pathological evidence of AF-CM remains limited.

Methods and Results: We retrospectively analyzed AF-CM patients who underwent both endomyocardial biopsy (EMB) from the right ventricle and catheter ablation (CA) for AF at Kyushu University Hospital between 2014 and 2023. We investigated the relationships between histological features and the recovery process of LV function in AF-CM after CA for AF. Recovery of LV ejection fraction (EF) was defined as an improvement ≥15%. EMB specimens were evaluated for myocardial fibrosis, cytoplasmic vacuolization, and nuclear expression of phosphorylated histone H2A variant X (γ-H2A.X) and poly(ADP-ribose) (PAR). Among 23 patients, the median time from CA to LVEF recovery was 145 days [90–220], and 83% achieved an LVEF ≥50%. Greater myocardial fibrosis, cytoplasmic vacuolization, and higher nuclear expression of γ-H2A.X and PAR were associated with delayed LVEF recovery (r=0.43, 0.42, 0.49, and 0.47, respectively). AF-CM severity scores derived from these histological features demonstrated associations with LVEF recovery time (R²=0.33 for the “structural damage score” and R²=0.29 for the “DNA damage score”).

Conclusions: In AF-CM patients undergoing CA, severe myocardial degeneration and DNA damage were associated with delayed recovery of LV systolic function.