Implantable cardioverter defibrillator therapy in adults with congenital heart disease: who is at risk of shocks?

BACKGROUND: The value of implantable cardioverter defibrillators (ICDs) in adults with congenital heart disease (CHD) is unknown. We investigated the long-term outcome after ICD implantation and developed a simple risk stratification score for ICD therapy. METHODS AND RESULTS: A total of 136 adults with CHD and ICD (mean age+/-SD, 41+/-13 years; 67% male) were identified from 10 tertiary referral centers in the Netherlands and Belgium. The indication for ICD implantation was primary prevention in 50% of patients. Diagnoses included tetralogy of Fallot (51%), septal defects (20%), (congenitally corrected) transposition of the great arteries (13%), and other (16%). Thirty-nine patients (29%) received appropriate ICD shocks during a median follow-up of 4.6 years. Secondary prevention indication (hazard ratio [HR], 3.6; 95% CI, 1.3-9.5; P=0.009), coronary artery disease (HR, 2.7; 95% CI, 1.0-7.2; P=0.042), and symptomatic nonsustained ventricular tachycardia (NSVT; HR, 9.1; 95% CI, 2.8-29.2; P=0.001) were associated with appropriate ICD shocks. A risk score was developed to evaluate the likelihood of appropriate ICD shocks. The 8-year survival curve to first appropriate shocks was 94%, 57%, and 26% for low-, intermediate-, and high-risk patients, respectively. In primary prevention, symptomatic NSVTs (HR, 8.0; 95% CI, 2.3-27.1; P=0.001) and subpulmonary ventricular dysfunction (HR, 3.0; 95% CI, 1.2-12.6; P=0.02) were associated with appropriate shocks in univariable analysis. Inappropriate shocks occurred in 41 patients (30%). In addition, 40 patients (29%) experienced 45 implantation-related complications. CONCLUSIONS: Adults with CHD and ICDs receive high rates of appropriate and effective shocks. Patients with secondary prevention indication, coronary artery disease, and symptomatic NSVT are at highest risk of receiving appropriate ICD shocks. ICD implantation is accompanied by considerable morbidity, including inappropriate shocks and procedure- related complications