Long-term follow-up of implantable cardioverter defibrillator patients with regard to appropriate therapy, complications, and mortality

Background An implantable cardioverter defibrillator (ICD) is recommended for patients with symptomatic heart failure with ejection fraction <= 35% despite optimal medical therapy. More recently, the benefits of ICDs have been questioned in nonischemic cardiomyopathy (CM). Aim To examine the incidence of appropriate therapy, complications, mortality, and cause of death among ICD patients in an unselected validated cohort. In primary prevention, appropriate therapy in ischemic versus nonischemic CM will be evaluated. Methods A retrospective observational study of patients in Region Gavleborg, Sweden, who underwent ICD implantation or replacement between 2007 and 2017. Results In total, 438 patients (mean age at implant: 65.9 +/- 11.2 years, 82.0% males, mean follow-up: 5.2 +/- 4.0 years) were included. There were 108 (24.7%) deaths (49.1% due to heart failure) and 94.9% survived the first year. Cumulative incidence of appropriate therapy at 5-year was 31.6%. Cumulative incidence of inappropriate shock at 5-year was 9.1%. A total of 98 complications requiring surgical intervention occurred (annual rate: 4.3%). In total, 236 patients with primary prevention due to ischemic (61.9%) or nonischemic (38.1%) CM were included. During a mean follow-up of 3.9 +/- 2.5 years, for appropriate therapy, there was no significant difference (P = .985) between ischemic (cumulative incidence at 1, 3, and 5 years: 6.4%, 17.1%, and 19.6%) and nonischemic CM (cumulative incidence at 1, 3, and 5 years: 5.6%, 13.6%, and 24.4%). Conclusion Ischemic and nonischemic CM confer similar risk of ventricular arrhythmia. This supports current guidelines regarding primary-prevention ICD. Short-term survival is excellent but complications remain a problem.