Abstract 13731: Randomized Trial of CMR Guidance for Cardiac Resynchronization Therapy: Findings in Nonischemic Cardiomyopathy From an Interim Analysis

Abstract

Introduction: Cardiac resynchronization therapy (CRT) response rates in unselected cohorts are suboptimal. Cardiac magnetic resonance (CMR) provides high-quality imaging of strain and scar, and post-CRT CMR offers reliable assessment of left ventricular (LV) reverse remodeling. Hypothesis: Cardiac magnetic resonance (CMR) guidance for CRT will increase CRT response rates, particularly in nonischemic cardiomyopathy (NICM). Methods: Patients were randomized 1:1 to standard CRT or CMR guidance for CRT using circumferential strain from Displacement Encoding with Stimulated Echoes (DENSE) and scar (late gadolinium enhancement [LGE]) by CMR. The primary endpoint is the percent change in LV end-systolic volume (LVESV) calculated from CMRs before CRT and 6 months after CRT. A pre-specified interim analysis by cardiomyopathy type was performed after completion of enrollment of 45 of the projected 90 patients needed for adequate power. Results: Of 45 patients enrolled (age 65.9 +/- 10.3 years, 29% female), two patients did not undergo a CRT procedure, and the LV lead could not be placed in one patient. Of the remaining 42 patients, 26/42 had NICM and 21/42 were randomized to CMR guidance. In a linear regression model for the primary endpoint adjusted for baseline QRS duration (p=0.04) and cardiomyopathy type (p=0.01), a favorable trend for the intervention on response was noted (p=0.06). Box plots demonstrate a significant difference in the primary endpoint among NICM patients (p=0.03) and a favorable trend for QRS shortening (0.07) in NICM patients (Figure). In all patients (including ICM patients), the overall p-value for the intervention relative to the primary endpoint was 0.08. Conclusion: An interim analysis in CRT patients with NICM demonstrated a favorable effect of CMR guidance on LV reverse remodeling after CRT, as assessed with post-CRT CMRs. Enrollment is continuing to evaluate the effect of the intervention on the entire cohort and other endpoints.