Sex Difference in Arrhythmic Risks and Prognosis in Patients with Nonischemic Cardiomyopathy

Background: Heart failure (HF) carries high mortality and comorbidities. Guidelines-directed medical and device therapy improves prognosis significantly. Although automatic intracardiac defibrillator (AICD) had 50% relative reduction in sudden cardiac deaths in patients with nonischemic cardiomyopathy (NICMP), there is no significant difference in overall mortality. Subgroup analysis of the two randomized controlled NICMP trials indicates no significant mortality benefits in female patients. Subjects and Methods: This single-center, retrospective study recruited 447 patients with HF and left ventricular ejection fraction (LVEF) <40% due to NICMP etiology, and those with significant coronary artery disease with more than 70% stenosis were excluded based on coronary angiogram. The primary endpoint was appropriate therapy from the device for ventricular arrhythmias and primary composite endpoints included death, appropriate therapy from device for ventricular arrhythmias and hospitalization for HF. Results: Female patients were older, had smaller left ventricles, narrower QRS, and higher LVEF at baseline. The mean follow-up duration was 6.18 ± 4.16 years. There were 61 deaths (13% vs . 2.20% deaths per year, 20 females and 41 males). Mean LVEF increased significantly from 24.88 ± 8.17% to 39.92 ± 13.88% in female patients and from 22.05 ± 8.52% to 36.14 ± 8.17% in male patients ( P = 0.023). LVEF increased to or more than 35% in 190 patients (43%). Forty patients (9%) received AICD or cardiac resynchronization therapy and the other 81% received primary prevention. The median time from diagnosis of NICMP to appropriate device therapy for ventricular arrhythmias was 7.13 years (interquartile range 2.92–10.92 years). All the device therapy occurred in patients with LVEF <35%. 18/21 patients (86%) had appropriate therapy for ventricular arrhythmias were males. Male patients also had significantly higher composite endpoints ( P = 0.0022). Conclusions: Guidelines-directed medical therapy improves left ventricular systolic function, reduces arrhythmic risks, and improves prognosis. The arrhythmic risk and composite endpoints are significantly higher in male than female patients.