Implantable cardioverter defibrillator resistant mortality in ischemic and dilated cardiomyopathy across therapeutic eras: a single, tertiary center experience

Abstract Background Since landmark trials conducted more than 2 decades ago, the implantable cardioverter defibrillator (ICD) has served as cornerstone in the prevention of sudden cardiac death in high-risk patients. Yet, recent improvements in cardiovascular preventive care and heart failure treatment raise questions about the role of ICDs in current clinical practice. Purpose To study the evolution of ICD-resistant mortality (ICDRM) in ischemic and dilated cardiomyopathy across different therapeutic eras. Methods All patients with an ischemic (ICM) or dilated cardiomyopathy (DCM) who have received an ICD in a tertiary care hospital were included in a single-center retrospective study. ICDRM is defined as (1) mortality within one year after implantation, (2) mortality without ever receiving appropriate ICD-therapy, or (3) mortality within 1 month after the first appropriate shock. The incidence of ICDRM was assessed across three different therapeutic eras (era 1:1996-2004; era 2: 2005-2013; era 3: 2014-2022), separated by changes in guidelines for primary prevention ICD-implantation and improvements in heart failure treatment, in the overall population and in different subgroups (primary (PP) vs. secondary prevention (SP), and ICM vs. DCM). The incidence of ICDRM was assessed as a proportion of the incidence of all-cause mortality. Results A total of 1,615 patients were included: 289 (17.9%) from era 1, 568 (35.2%) from era 2 and 758 (46.9%) from era 3. Across eras, the median age at implant (66, 64 and 67; p<0.001); the proportion of females (33 (11.4%), 105 (16.0%) and 164 (21.6%); p <0.001), the proportion of DCM implants (53 (18.3%), 228 (40.1%) and 317 (41.8%); p <0.001) and the proportion of primary prevention indications (75 (26.0%), 389 (68.5%) and 586 (77.3%); p <0.001) increased. Incidences and proportions in the overall population, and in ICM and DCM, are shown in figure 1 and 2. Across therapeutic eras, the proportion of ICDRM has risen in the overall population and in the subgroups. In the total population, the incidence of ICDRM per 100 person-years was 3.6% in era 1, 3.7% in era 2 and 4.7% in era 3, respectively. ICDRM accounted for 43.4%, 56.9% and 87.0% of total mortality, respectively. The proportion of ICDRM in ICM and DCM was 45.5% and 38.3% in era 1, 56.0% and 56.4% in era 2 and 85.5% and 91.2% in era 3, respectively. The proportion of ICDRM in PP and SP was 50.0% and 43.0% in era 1, 56.7% and 54.5% in era 2, and 90.2% and 73.8% in era 3. Conclusion This retrospective analysis shows that in the current era the majority of patients die without having received antiarrhythmic benefit of their ICD. The decline in the clinical utility of ICDs was consistent across recent eras for patients with ICM and DCM, and in both PP and SP groups. These findings confirm the need for updated evidence to guide ICD use in current clinical practice.Figure 1 Figure 2.