Absence of left bundle branch block and blood urea nitrogen predict improvement in left ventricular ejection fraction in patients with cardiomyopathy and wearable cardioverter defibrillators

OBJECTIVE: To identify predictors of left ventricular ejection fraction (LVEF) improvement in patients with newly detected cardiomyopathy using wearable cardioverter defibrillators (WCDs). BACKGROUND: WCDs are useful in preventing sudden cardiac death in patients with reduced LVEF <35% while awaiting implantable cardioverter defibrillator (ICD) placement. In many patients, LVEF improves and an ICD is not indicated. METHODS: Patients who received WCDs from November 2013 to November 2015 were identified and followed over a period of 2 years. Clinical variables were examined. The primary outcome was improvement in LVEF ≥35%. Predictors of outcome were determined using a multivariate logistic regression model. RESULTS: A total of 179 patients were followed. Median age was 65 (interquartile range [IQR]: 56, 73) years, 69.3% were men. Median baseline LVEF was 20% (IQR: 15, 30). LVEF improved ≥35% in 47.5% patients, with patients being younger (62 vs 68.5 years, P = .006), having lower blood urea nitrogen (BUN) (19 vs 24 mg/dL, P = .002), fewer left bundle branch block (LBBB 9.5% vs 25.8%, P = .004), shorter QRS duration (98 vs 112 ms, P < .001), and higher use of angiotensin converting enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB) (92.9% vs 74.4%, P = .001) compared to those without LVEF improvement. Absence of LBBB (odds ratio [OR] 0.28, 95% confidence interval [CI] 0.11‐0.70), lower BUN (OR 0.13, 95% CI 0.02‐0.76), and ACEI/ARB use (OR 3.53, 95% CI 1.28‐9.69) were identified as independent predictors. Ventricular tachycardia/ventricular fibrillation was observed in three patients, all of whom received successful WCD shocks. CONCLUSION: Absence of LBBB, lower BUN, and ACEI/ARB use predicts LVEF improvement. WCDs help treat arrhythmic events.