Clinical importance of new-onset atrial fibrillation after cardiac resynchronization therapy

BACKGROUND Data on the occurrence and implications of new-onset atrial fibrillation (AF) following cardiac resynchronization therapy (CRT) are scarce. We studied the incidence of new onset AF in CRT-defibrillator (CRT-D) recipients. The influence of new-onset AF on echocardiographic response to CRT and the rate of adverse events also were evaluated. OBJECTIVE The purpose of this study was to assess the incidence and implications of new-onset AF following CRT. METHODS The study population consisted of 223 consecutive patients with no history of AF. New-onset AF was defined as atrial high-rate episodes > 180 bpm for more than 10 minutes/day as detected by the device. Echocardiography was performed at baseline and after 6 months of biventricular pacing. Long-term events included implantable cardioverter-defibrillator therapy for ventricular arrhythmias, hospitalization for heart failure, and all-cause mortality. RESULTS Fifty-five (25%) patients developed new-onset AF during mean follow-up of 32 16 months. When compared to the patients who maintained sinus rhythm during follow-up, patients who developed AF showed less Left ventricular (LV) reverse remodeling (Delta LV end-systoLic volume 37 +/- 53 vs > 19 +/- 37 mL, P < .05) and Less improvement in LV function (Delta LV ejection fraction 6.7% +/- 8.9% vs 3.5% +/- 10.3%, P < .05). Importantly, patients who developed AF experienced more appropriate ICD shocks for ventricular arrhythmias, more inappropriate shocks, and more hospitalizations for heart failure. CONCLUSION Recipients of CRT-D who develop new-onset AF show less echocardiographic response to CRT and more cardiac adverse events during long-term follow-up.