Effectiveness, safety, and other factors associated with success of cardioversion (CV) of atrial fibrillation (AF) have not yet been evaluated in patients with reduced left ventricular ejection fraction. We studied 148 consecutive patients with left ventricular dysfunction (ejection fraction ≤45%), who underwent electrical CV for AF in our department. The patients had New York Heart Association heart failure ranging from class II to IV. The overall CV success rate was 71%. We relied on univariate and multivariate regression and sought variables influencing success rate. Conversion success did not correlate with New York Heart Association class. Instead, we found that the greatest predictor was the degree of heart failure treatment. Patients receiving β-blockers, angiotensin-converting enzyme inhibitors or angiotension receptor blockers, plus mineralocorticoid receptor blockers had the greatest chance for conversion success. Success was more likely in patients with coronary artery disease (91%) than in patients with nonischemic cardiomyopathy.

Cardioversion is a safe and effective method for the restoration of sinus rhythm in patients with AF and reduced left ventricular ejection fraction. Our findings underscore the value of aggressive heart failure treatment before CV in patients with AF.