Long-Term Survival With Implantable Cardioverter-Defibrillator in Different Symptomatic Functional Classes of Heart Failure

Abstract

The ACC/AHA/HRS (American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society) guidelines recommend implantable cardioverter-defibrillator (ICD) therapy primary prevention in all patients with severely reduced left ventricular ejection fraction (≤30%) regardless of New York Heart Association (NYHA) functional class, whereas recent European guidelines limit the indication to those with symptomatic heart failure (NYHA ≥ II). We therefore aimed to evaluate the long-term survival benefit of primary ICD therapy among postmyocardial infarction patients with and without heart failure (HF) symptoms who were enrolled in MADIT-II (Multicenter Automatic Defibrillator Implantation Trial II). We classified 1,164 MADIT-II patient groups according to the baseline NYHA class (NYHA I [n = 442], NYHA II [n = 425], and NYHA III [n = 297]); patients with NYHA IV were excluded. Multivariate Cox proportional hazards regression modeling was performed to compare the mortality reduction with ICD versus non-ICD therapy during 8 years of follow-up between the 3 NYHA groups. The median (interquartile range) follow-up time was 7.6 (3.5 to 9) years. At 8 years of follow-up, the cumulative probability of mortality in the non-ICD treatment arm was 57% for NYHA I, 57% for NYHA II, and 76% for NYHA III (p <0.001). Multivariate models demonstrated similar long-term mortality risk reduction with ICD compared with the non-ICD treatment arm regardless of HF symptoms: NYHA I (HR = 0.63, 0.46 to 0.85, p = 0.003), NYHA II (HR = 0.68, 0.50 to 0.93, p = 0.017), and NYHA III (HR = 0.68, 0.50 to 0.94, p = 0.018); p for NYHA class by treatment arm interaction >0.10. In conclusion, primary ICD therapy provides consistent long-term survival benefit among patients with previous myocardial infarction and severe left ventricular dysfunction, regardless of HF symptoms.