Abstract 14932: Effects of Cardiac Resynchronization Therapy in Ischemic Cardiomyopathy Patients by Revascularization Procedures in MADIT-CRT

Abstract

Background: The Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT) showed that patients with ischemic cardiomyopathy (ICM) had similar reductions in clinical events with implanted CRT-D vs. ICD-only when compared to patients with non-ischemic cardiomyopathy (NICM). Frequency of revascularizations may serve as a surrogate for severity of coronary artery disease in patients with ICM and severely reduced left ventricular ejection fraction. However, it is unknown whether the number of revascularizations plays a role in clinical outcomes in ICM patients implanted with CRT-D vs. ICD-only. Methods: Using a multivariable analysis of MADIT-CRT data, we evaluated the effect of CRT-D vs. ICD-only on combined heart failure (HF) or death and combined ventricular tachycardia (VT), ventricular fibrillation (VF) or death in ICM patients by the number of pre-enrollment revascularizations (1 or ≥ 2 revascularizations) compared to those with no need for revascularization. Follow-up over a median period of 5.6 years for HF/death and 4.0 years for VT/VF/death was assessed among 1374 ICM patients with a Left Bundle Branch Block (LBBB). Results: There was a significant and similar risk reduction with CRT-D vs. ICD-only in HF/death in all three sub-groups: ICM with no need for revascularization (HR 0.45 [0.26-0.80]; p < 0.006), ICM with one revascularization (HR 0.46 [0.31-0.69]; p <0.001), and ICM with 2 or more revascularization (HR 0.50 [0.30-0.84]; p = 0.008). However, significant risk reduction of VT/VF/death with CRT-D vs. ICD-only was only observed in patients with no need for revascularization (HR 0.52 [0.30-0.89]; p = 0.017), less so in those with ICM with one revascularization (HR 0.72 [0.49-1.06]; p = 0.10), and no reduction was seen in those with ICM with 2 or more revascularization (HR 0.94 [0.54-1.62]; p = 0.81). Conclusions: In ischemic cardiomyopathy patients, CRT-D vs. ICD-only is associated with a significant risk reduction in heart failure events or death irrespective of the frequency of pre-enrollment revascularization procedures; however, the benefit of CRT-D vs. ICD-only to reduce ventricular tachyarrhythmias is attenuated with the increasing number of revascularization procedures.