[How many leads are needed for an ICD?].

In addition to secondary prevention of sudden cardiac death (SCD), the number of cardioverter defibrillator implantations (ICD) for primary prevention is increasing. An indication for primary prevention of SCD is supported by results of the MADIT II, Companion and SCD-HeFT trials. The main risk factor for SCD is the reduced left ventricular function (LVEF < or = 35%). For selecting the appropriate ICD device and the number of leads, several clinical parameters are important. For the primary prevention of SCD a single-lead VVI ICD is usually sufficient. In case of AV conduction delay and symptomatic heart failure with a prolonged QRS duration a biventricular ICD device is preferred in favor of a ventricular resynchronization. The use of a dual-chamber device should be limited to sinus nodal disease and better discrimination capabilities for slow ventricular tachycardias.