Time-dependence of appropriate implantable defibrillator therapy in patients with ischemic cardiomyopathy

Area of Science:

• Cardiology
• Electrophysiology
• Medical Devices

Background:

• Limited data exists on implantable cardioverter-defibrillator (ICD) therapy outside clinical trials.
• Routine practice patient follow-up and device replacement questions are critical.
• Understanding long-term outcomes in primary prevention is essential.

Purpose of the Study:

• To assess the incidence and time-dependence of appropriate ICD therapy.
• To evaluate outcomes in a primary prevention population with prior myocardial infarction (MI) and reduced left ventricular ejection fraction (LVEF).
• To inform clinical practice regarding device longevity and replacement strategies.

Main Methods:

• Retrospective analysis of 525 patients receiving ICDs for primary prevention (1995-2005).
• Inclusion criteria: prior MI and LVEF ≤35%.
• Determination of incidence and time-dependence of first appropriate ICD therapy for ventricular arrhythmia (VA) and rapid VA.

Main Results:

• 22% of patients (115/525) received appropriate ICD therapy.
• First appropriate ICD therapy incidence was 20% in year 1, decreasing to 12% in year 2, and 6-11% annually thereafter.
• A similar trend was observed for rapid VA, with a persistent risk up to year 7.

Conclusions:

• Appropriate ICD therapy incidence is highest in the first year post-implant for primary prevention patients.
• The risk of ventricular arrhythmia requiring ICD therapy persists for at least seven years.
• ICD replacement appears indicated for all patients due to persistent risk.