Late gadolinium enhancement and outcome of cardiac resynchronization therapy in non-ischemic cardiomyopathy

Background: It is uncertain whether CRT with defibrillator (CRTD) is superior to CRT with pacemaker (CRTP) in NICM. Patients with low arrhythmic risk and high probability of response to CRT might be ideal candidates for CRTP. We aimed to evaluate predictors of ventricular arrhythmias and of echocardiographic response to cardiac resynchronization therapy (CRT) in non-ischemic cardiomyopathy (NICM). Methods: Multicenter, retrospective observational study of NICM patients with left ventricular ejection fraction (LVEF) <= 35 %, cardiac magnetic resonance with analysis of late gadolinium enhancement (LGE) available and de-novo CRT implant. Echocardiographic response to CRT was defined as an improvement in LVEF >= 10 %. The combined arrhythmic endpoint included sustained ventricular tachycardia, appropriate ICD therapy, resuscitated cardiac arrest and sudden death. Results: We included 167 patients, with a median follow-up of 63 months. LGE was present in 77 (46 %). Response to CRT occurred in 68 % of patients, more frequently in LGE- than in LGE+ (81 % vs 53 %, p < 0.001). Absence of LGE (OR 3.4, p = 0.002), was an independent predictor of response to CRT. The arrhythmic endpoint occurred in 19 patients (11 %). Among LGE- patients there were zero arrhythmic events as compared to a 25 % cumulative incidence in LGE+ (p < 0.001). Presence of LGE (HR 22.5, p < 0.001), was an independent predictor of the arrhythmic endpoint. Conclusion: Absence of LGE identifies patients at minimal arrhythmic risk and with high probability of response to CRT. Thus, they might be ideal candidates to CRT-P.