Current Status of Implantable Cardioverter-Defibrillators (ICDs)/Cardiac Resynchronization Therapy With Defibrillators (CRT-Ds) for Primary Prevention of Sudden Cardiac Death.

Among recipients of implantable cardioverter-defibrillators (ICDs) or cardiac resynchronization therapy with defibrillators (CRT-Ds), non-ischemic etiology is predominant, accounting for more than 60% of cases in Japan, which is higher than that in the United States and other European countries. Despite recent concerns about primary prevention ICD/CRT-D implantation for non-ischemic patients with systolic heart failure in advanced guideline-directed medical therapy (GDMT), ICD/CRT-D therapy is likely effective in reducing the slope of the relationship between all-cause death and sudden cardiac death. Two cohort studies in Japan have shown that the cumulative incidence of appropriate ICD/CRT-D therapy is higher among non-ischemic patients than ischemic patients receiving primary prevention ICD/CRT-D implantation. Additionally, recent published cohort studies in the United States, Europe, and Japan reported a significant decrease in the risk of all-cause death in primary prevention ICD/CRT-D recipients compared to those without ICD/CRT-D therapy. Notably, ICD/CRT-D utilization in Japan is the lowest among the Group of Seven (G7) countries. Governmental acknowledgment of the value of primary prevention ICD/CRT-D therapy, as well as educational activities for non-cardiac electrophysiologists, are required to prevent a potential labor shortage and an excess of healthcare costs following out-of-hospital cardiac arrest (OHCA).