The ICD for Primary Prevention in Patients With Inherited Cardiac Diseases Indications, Use, and Outcome: A Comparison With Secondary Prevention

Background- Indications for prophylactic implantable cardioverter-defibrillator (ICD) therapy in patients with inherited cardiac diseases stem from observational studies and are uncertain. This study evaluates the efficacy and harm rate of ICD implantations for primary prevention compared with secondary prevention in inherited cardiac diseases. Methods and Results- Between January 1, 1993, and April 1, 2011, 354 patients with inherited cardiac diseases were treated with ICDs. Incidence rates of appropriate shocks in primary prevention patients with arrhythmogenic right ventricular cardiomyopathy and hypertrophic cardiomyopathy were 4.2 to 6.7/100 patient-years, whereas the risk for appropriate shocks in primary prevention patients with Brugada syndrome, long QT syndrome, or carrying the DPP6 haplotype approached zero. Conversely, in secondary prevention patients there was a considerably higher incidence rate of appropriate shocks. None of the indications for primary prevention were associated with appropriate shock therapy. One hundred twenty-three patients (35%) experienced ICD-related adverse events. Conclusions- For Brugada syndrome, long QT syndrome, and DPP6 the efficacy of an ICD for primary prevention contrasts with the amount of harm, and factors that formed the indication for ICD implantation do not relate to the occurrence of appropriate shocks. The higher appropriate discharge rates in arrhythmogenic right ventricular cardiomyopathy and hypertrophic cardiomyopathy compared with primary electric diseases might result from a more advanced risk stratification scheme in these inherited cardiomyopathies.