Predictors and implications of early left ventricular ejection fraction improvement in new-onset idiopathic nonischemic cardiomyopathy with narrow QRS complex: A NEOLITH substudy.

Background: Predictors and implications of early left ventricular ejection fraction (LVEF) improvement with guideline-directed medical therapy (GDMT) in new-onset idiopathic nonischemic cardiomyopathy (NICM) with narrow QRS complex are not well described. The objectives were to describe predictors of LVEF improvement after 3 months on GDMT and adverse cardiac events based on post-GDMT LVEF status (≤35% vs. >35%).

Methods: A retrospective cohort study was performed in subjects with new-onset NICM, LVEF ≤35%, and narrow QRS complex. Associations for baseline variables with post-GDMT LVEF improvement and absolute change in LVEF (∆LVEF ) were assessed. Cox proportional hazards models assessed associations for post-GDMT LVEF status with adverse cardiac events.

Results: In 70 subjects, 31 (44%) had post-GDMT LVEF ≤35% after a median follow-up time of 97.5 days (interquartile range, 84-121 days). In final multivariable models, severely dilated left ventricular end-diastolic diameter (LVEDD), compared with normal LVEDD, strongly predicted post-GDMT LVEF ≤35% (odds ratio, 7.77; 95% confidence interval [CI], 1.39-43.49; p = .02) and ∆LVEF (β = -15.709; standard error = 4.622; p = .001). Subjects with post-GDMT LVEF ≤35% were more likely to have adverse cardiac events over a median follow-up time of 970.5 days (unadjusted hazard ratio, 2.15; 95% CI, 0.93-4.96; p = .07). In the post-GDMT LVEF ≤35% group, 9 of 26 subjects (35%) had long-term LVEF > 35%.

Conclusion: In new-onset NICM with narrow QRS complex, nondilated LVEDD predicted early LVEF improvement. Those with post-GDMT LVEF ≤35% had higher risk of adverse cardiac events, but a substantial proportion demonstrated continued long-term LVEF improvement.