A 44-year-old woman with restrictive cardiomyopathy showed right-sided dominant heart failure after conversion to sinus rhythm from paroxysmal atrial fibrillation (AF). During cardiac catheterization, the hemodynamics were compared before and after cardioversion; that is, with AF and with sinus rhythm. The hemodynamic parameters worsened after conversion to sinus rhythm, with a significant decrease in heart rate, but improved with atrial pacing. Pacemaker implantation was performed to avoid bradycardia while keeping the sinus rhythm with amiodarone. As a result, the patient has been free from symptoms of heart failure for almost 1 year and her serum brain natriuretic peptide level also improved remarkably.