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

Area of Science:

• Cardiology
• Medical Devices
• Clinical Practice Guidelines

Background:

• Current guidelines differ on primary prevention implantable cardioverter-defibrillator (ICD) use for patients with severely reduced left ventricular ejection fraction (LVEF ≤30%).
• American guidelines recommend ICD for LVEF ≤30% irrespective of heart failure (HF) symptoms.
• European guidelines restrict ICD indication to symptomatic HF (NYHA class ≥II).

Purpose of the Study:

• To evaluate the long-term survival advantage of primary ICD therapy in post-myocardial infarction patients with LVEF ≤30%.
• To compare ICD effectiveness across different New York Heart Association (NYHA) functional classes (I, II, III) in the MADIT-II trial.
• To determine if HF symptoms influence the mortality benefit of ICD therapy.

Main Methods:

• Analysis of 1,164 patients from the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II) with LVEF ≤30%.
• Patients were stratified by baseline NYHA class (I, II, III).
• Multivariate Cox proportional hazards regression analyzed 8-year mortality risk reduction with ICD vs. non-ICD therapy.

Main Results:

• At 8 years, cumulative mortality in the non-ICD arm was 57% for NYHA I, 57% for NYHA II, and 76% for NYHA III.
• ICD therapy demonstrated a consistent, significant mortality risk reduction across all evaluated NYHA classes (NYHA I: HR 0.63; NYHA II: HR 0.68; NYHA III: HR 0.68).
• No significant interaction was found between NYHA class and treatment arm, indicating similar ICD benefit regardless of HF symptom severity.

Conclusions:

• Primary ICD therapy provides a consistent long-term survival benefit for patients with previous myocardial infarction and severe left ventricular dysfunction.
• The mortality benefit of ICDs in this population is independent of the presence or severity of heart failure symptoms.
• Findings support the American guideline recommendation for primary ICD use in patients with LVEF ≤30% regardless of HF symptoms.