Evolution of Primary Prevention Implantable Cardioverter-Defibrillator Clinical Utility Across Therapeutic Eras in Ischemic and Non-Ischemic Cardiomyopathy.

Background: The implantable cardioverter-defibrillator (ICD) serves as cornerstone in the prevention of sudden cardiac death (SCD). Improvements in heart failure treatment have led to a decrease in SCD incidence.

Objective: To evaluate temporal trends in appropriate ICD interventions and ICD-resistant mortality (ICDRM) in patients with ischemic (ICM) and non-ischemic cardiomyopathy (NICM), and a primary prevention (PP) ICD indication.

Methods: All patients with ICM or NICM and a PP ICD indication, who have received an ICD in a tertiary care hospital were included in a single-center retrospective study. Incidences of appropriate ICD interventions, ICDRM, and all-cause mortality were analyzed across three therapeutic eras (era 1:1996-2004; era 2: 2005-2013; era 3: 2014-2022) in the overall population, and for patients with ICM or NICM exclusively. ICDRM is defined as mortality occurring in ICD recipients (1) without the device delivering appropriate therapy, (2) within one year after ICD implantation, or (3) within one month after the first appropriate shock.

Results: A total of 1,050 patients were included (20.4% female, median age of 64 years, 44.7% CRT). Across eras, there was a significant decline in appropriate shock incidence for both ICM and NICM (p<0.001). For patients with ICM, the incidence of ICDRM increased from 3.7%/year (50.0% of all mortality) in era 1 to 5.6%/year (88.9%) in era 3. For NICM, incidences increased from 1.2%/year (26.1%) to 3.2%/year (97.0%), respectively.

Conclusion: The decline in clinical utility of PP ICDs in both ICM and NICM warrant updated evidence to guide ICD use in contemporary practice.