Mortality benefit of implantable cardioverter-defibrillators for primary prevention of sudden cardiac death: a real-world analysis

Abstract

Abstract Background Nearly 1,000 people suffer an out-of-hospital sudden cardiac arrest daily in the United States, with only 10% surviving when treated by emergency medical services. Implantable cardioverter-defibrillators (ICDs) are a proven first-line treatment in limiting sudden cardiac death, but the evidence has become dated. We sought to assess the survival benefit of ICDs in a contemporary population. Purpose Using a real-world database, we aimed to determine the current impact of ICDs on mortality in primary prevention patients. Methods Data were obtained from a de-identified electronic health record database. We included patients that met ICD primary prevention indication (PPI) implantation criteria between 2012 and 2019, had one year of available data before the PPI, and survived for at least one year post-PPI. Patients were split into 2 groups based on ICD implant status (implanted vs not implanted) within one year after PPI. The primary endpoint was the overall mortality rate, beginning at one-year post-PPI. Propensity matching was performed to account for baseline differences between patients that did and did not receive an ICD, and all-cause mortality rates were compared using the Kaplan-Meier method and Cox proportional hazard model. Results A total of 25,296 patients were identified as having a PPI for ICD implantation, of which 2,118 (8.4%) were implanted with an ICD within a year. Implanted patients were younger than non-implanted patients (63.4 vs 66.1 years) and had a smaller proportion of females (25.0% vs 36.7%). After 4 to 1 propensity matching, patients who did not have an ICD implanted had a mean age of 63.6 years and were 25.1% female. In the matched cohort, the 5-year all-cause mortality rate was 37.6% (CI: 33.2%-41.7%) in PPI patients who received an ICD and 44.9% (CI: 42.8%-47.0%) in those that did not receive an ICD. A Cox proportional hazard model revealed a 25.3% lower risk of all-cause mortality in PPI patients implanted with an ICD compared to PPI patients without an ICD (HR: 0.747; CI: 0.670-0.834; p<0.001 [Figure 1]). Conclusion In a large cohort of PPI patients that survived at least one year after indication, those implanted with an ICD during that year had a 25.3% lower risk of all-cause mortality than similar patients who did not receive an ICD, consistent with landmark trials. Thus, ICD implantation continues to be associated with a reduction in all-cause mortality in PPI patients at risk for sudden cardiac death.