Significance of follow-up left ventricular ejection fraction measurements in the Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation trial (DEFINITE)

Abstract

Background: As left ventricular ejection fraction (LVEF) may improve, worsen, or remain the same over time, patients' prognosis may also be expected to change because of the change in LVEF, among other factors.

Objective: To evaluate the effect of LVEF change on outcome in the Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial.

Methods: Patients with nonischemic cardiomyopathy with LVEF<36%, history of symptomatic heart failure, and the presence of significant ventricular ectopic activity were enrolled in the DEFINITE trial. Follow-up LVEF measurements were obtained annually in only a minority (17%) of trial participants. This study therefore evaluated survival and arrhythmic end points in patients whose LVEF was reassessed between 90 and 730 days after enrollment.

Results: During the 90-730-day postrandomization period, 187 of 449 (42%) enrolled patients who survived at least 90 days had at least 1 follow-up LVEF measurement; these patients were younger and white; had diabetes, better 6-minute walk test results, and higher BMI; were more likely to have appropriate shocks; and had fewer deaths compared to those without follow-up LVEF measurements. Patients whose LVEF improved had reduced mortality compared to patients whose LVEF decreased (hazard ratio 0.09; 95% confidence interval 0.02-0.39; P = .001). Survival free of appropriate shocks was not significantly related to LVEF improvement during follow-up.

Conclusions: LVEF improvement was associated with improved survival, but not with a significant decrease in appropriate shocks. These data highlight that appropriate caution should be exercised not to extrapolate the positive effect of improved LVEF to the elimination of arrhythmic events.