Background: Sinus rhythm restoration (SRR) in patients in atrial fibrillation and heart failure may improve systolic function and impact on consecutive clinical management such as ICD-implantation.

Purpose: To investigate time course and potential predictors of the response to SSR.

Methods: We prospectively studied 50 consecutive patients who presented in heart failure with reduced ejection fraction and concomitant AF. After exclusion of valvular and coronary artery disease patients underwent electrical cardioversion. Serial echocardiography, cardiac magnetic resonance imaging (cMRI), and 24h-ECGs were performed at baseline, and on days 3 and 40 following SRR.

Results: Baseline left ventricular ejection fraction (EF) of the study population (76% male, age 69±11y) was 30±7%. Sustained SRR (≥ three days) significantly improved EF (figure 1A; day 3: 43±7%, n=46; day 40: 53±9%, n=34; p<0.001) as quantified by echocardiography. Comparable results were obtained using cMRI (baseline: 29±8%; day 3: 42±9%).  Three patients showed no response to SRR (EF-improvement <15%). The percentage of patients meeting current criteria for ICD-implantation for primary prevention dropped from 76% (n=38) to 11% (n=3) on day 40 following SRR (figure 1B). No specific clinical or echocardiographic factor predicting improved EF after SRR could be identified.

Conclusions: The majority of patients presenting with non-ischemic, non-valvular heart failure with reduced ejection fraction and concomitant AF show a significant and rapid improvement in EF following SRR. An attempt at SRR and reassessment of the need for ICD implantation after 40 days may be warranted in all such patients.