Left Ventricular Ejection Fraction Normalization in Cardiac Resynchronization Therapy and Risk of Ventricular Arrhythmias and Clinical Outcomes

Abstract

BACKGROUND: -Appropriate guideline criteria for use of ICDs do not take into account potential recovery of left ventricular ejection fraction (LVEF) in patients treated with CRT-D.METHODS AND RESULTS: -Patients randomized to CRT-D from the MADIT-CRT trial, who survived and had paired echocardiograms at enrollment and at 12-months (n=752) were included. Patients were evaluated by LVEF recovery in 3 groups (LVEF≤35% (reference), LVEF:36-50%, and LVEF>50%) on outcomes of ventricular tachyarrhythmias (VTA), VTA≥200 bpm, ICD-shock, heart failure or death and inappropriate ICD therapy by multivariable Cox models. A total of 7.3% achieved LVEF normalization>50%. Average follow-up hereafter was 2.2±0.8 years. The risk of VTA was reduced in LVEF>50% (HR:0.24, CI:0.07-0.82, p=0.023) and LVEF:36-50% (HR:0.44, CI:0.28-0.68 p<0.001). Among patients with LVEF>50% only 1 had VTA≥200 bpm (HR:0.16, CI:0.02-1.51), none were shocked by the ICD and 2 died of non-arrhythmic causes. The risk of HF/death was reduced with improvements in LVEF (>50%: HR:0.29, CI:0.09-0.97 p=0.045 and LVEF:36-50%: HR:0.44, CI:0.28-0.69 p<0.001). For inappropriate ICD therapy no additional risk reduction for LVEF>50% was seen when compared to LVEF:36-50%. A total of 6 factors were associated with LVEF normalization and patients with all factors present (n=42) did not experience VTAs (PPV=100%).CONCLUSIONS: -Patients who achieve LVEF normalization (>50%) have very low absolute and relative risk of VTAs and a favorable clinical course within 2.2 years of follow-up. Risk of inappropriate ICD therapy is still present and these patients could be considered for downgrade from CRT-D to CRT-P at time of battery-depletion if no VTAs have occurred. Clinical Trial Registration Information-www.clinicaltrials.org. Identifier: NCT00180271.