Abstract 2198: Rhythmic Risk in Idiopathic Dilated Cardiomyopathy Depending on the Evolution of Left Ventricular Ejection Fraction in Patients with Implantable Cardioverter Defibrillators

Abstract

Background : Patients with idiopathic dilated cardiomyopathy (DCM) receiving an ICD often improve their left ventricular dysfunction in the year following implantation due to reverse remodelling and/or optimization of concomitant drug therapy. We examined whether this improvement impacts the benefit of ICD in terms of appropriate therapy. Methods : The study comprised 93 consecutive DCM patients with LVEF <35% and an indication for ICD (primary prevention = 37, secondary prevention = 56). Follow-up duration was 12 to 42 (median 25) months. LVEF was reassessed 5 to 13 (median 7) months after implantation and compared with baseline value at implantation. Concomitant drug therapy with ACE inhibitors and beta blockers was optimized during the same period, according to recent guidelines. All arrhythmic events were assessed by ICD memory interrogation during follow-up. Major (MaAE) and minor (MiAE) arrhythmic events were defined as appropriate shock or ATP for sustained ventricular tachyarrhythmias >200 bpm or <200 bpm respectively. Early events (before LVEF evaluation) were separated from late events (after LVEF evaluation). Results : Overall the mean LVEF increased by 7.2 % from 24.6±7% at baseline to 31.8±12% at revaluation. Two patterns were observed: 23 patients had a >14% LVEF increase (group 1) whereas 70 others had an increase <14% in LVEF (group 2). In group 1, 3 MaAE and 1 MiAE occurred in the early period but no event in the late period. In contrast, MaAE were observed in 15 and MiAE in 31 patients from group 2 during the late period. On multivariate analysis, changes in LVEF was an independent predictor of MaAE (OR=0.85; 95% CI 0.77 to 0.95; p=0.005) and MiAE (OR=0.91; 95% CI 0.84 to 0.99; p=0.02) during the late period. On multivariate analysis LVEF improvement was negatively correlated to diuretic use and QRS duration at baseline and to the absence of moderate or severe mitral regurgitation. Conclusions : In DCM, rhythmic risk is dynamic and inversely related to the improvement in LVEF. Reverse remodelling under optimal therapy is associated with a late favourable outcome, but 17% of these patients however benefit from ICD therapy in the early period.