Abstract 2688: Persistent Risk of Appropriate ICD Therapy for Up to 7 Years in Patients with Ischemic Cardiomyopathy and Low Ejection Fraction
BACKGROUND: In clinical trials of implantable cardioverter-defibrillators (ICD) for primary prevention of sudden death in patients with ischemic cardiomyopathy (ICMP) and left ventricular ejection fraction (LVEF) ≤ 35 %, the incidence of appropriate ICD therapy ranges from 7 to 12 % per year. Less is known about the incidence and timing of appropriate ICD therapy in such a population when treated outside the context of controlled clinical trials. Using a prospectively maintained single-center ICD registry, we assessed the incidence and time course of appropriate ICD therapy in a primary prevention population with ICMP and low LVEF.
METHODS: Patients with ICMP and LVEF ≤ 35 % who received an ICD at our institution between 1995 and 2005 were identified. Patients who presented with cardiac arrest, sustained ventricular tachycardia, or syncope were excluded. Incidence and time-dependence of first appropriate ICD therapy was determined.
RESULTS: We identified 529 patients with ICMP and LVEF ≤ 35 who received an ICD for primary prevention (82% male, median age 67 years, median LVEF 25%), of which 113 (21%) received appropriate ICD therapy a median of 8 months after implant (range 1 day to 8 years). Incidence of appropriate ICD therapy was highest in the first year post implant (20%), decreased to 11% in the second year, and remained within a stable range of 7 to 10% thereafter (FIGURE⇓).
CONCLUSION: In an uncontrolled primary prevention population with ICMP and low LVEF receiving ICDs, the incidence of appropriate ICD therapy is highest in the first year post implant. While the annual incidence decreases thereafter, it remains relatively constant at 7 to 10 % per year as far as 7 years post implant.