Prophylactic implantable defibrillators in dilated cardiomyopathy

Arrhythmia risk stratification with regard to prophylactic implantable cardioverter–defibrillator (ICD) therapy was investigated in the Marburg Cardiomyopathy Study, which revealed left ventricular ejection fraction to be the only significant independent arrhythmia risk predictor in a relatively large dilated cardiomyopathy (DCM) patient population. Based of the favorable results of the SCD-HeFT Trial, prophylactic ICD therapy became a class I indication for patients with DCM, NYHA class II or III heart failure and a left ventricular ejection fraction ≤ 35% despite optimized medical therapy. In addition, prophylactic ICD therapy combined with cardiac resynchronization became standard treatment in DCM patients with complete left bundle branch block and an ICD indication according to SCD-HeFT criteria. Unresolved issues of prophylactic ICD therapy in DCM include a high number to treat in order to save one patient from sudden death due to difficult arrhythmia risk stratification which is largely based on reduced left ventricular ejection fraction. Second, optimal timing of prophylactic ICD implant remains difficult, because a significant but unpredictable number of DCM patients show a marked improvement of left ventricular function during follow-up, thus, averting the need prophylactic ICD therapy. Finally, prophylactic ICD therapy is associated with a considerable complication rate with painful inappropriate shocks and lead-related problems being the most frequent complications during long-term follow-up.