Managing atrial tachyarrhythmias in patients with implantable cardioverter defibrillators.

The implantable cardioverter defibrillator (ICD) is accepted as the therapy of choice in preventing sudden cardiac death. Multiple studies, such as Antiarrhythmics Versus Implantable Defibrillators (AVID), the Canadian Implantable Defibrillator Study (CIDS), the Cardiac Arrest Study Hamburg (CASH), and the Multicenter Automatic Defibrillator Implantation Trial (MADIT), have shown a substantial benefit in survival rates for patients treated with ICDs compared with antiarrhythmic drug treatment. The detection of spontaneous ventricular tachycardias (VT) is based primarily on the programmed heart rate for intervention of the device. Supraventricular tachycardias (SVTs) cause unnecessary therapy delivery in about 10-20% of patients with ICDs. ICD therapy needs to be improved to become more specific for VT detection, by implementing algorithms that discriminate between VTs and SVTs. The enhanced detection criteria in currently available ICD devices are able to decrease the rate of unnecessary therapy to < 5% of patients. Atrial tachyarrhythmias can be managed with programmable features of the device, antiarrhythmic drug treatment, and in rare cases, ablation procedures. Dual-chamber ICDs, requiring an additional atrial lead, are indicated in specific situations of slow VT and concurrent, continuous SVTs at very similar heart rates. Using all these options, SVTs can be managed to achieve an acceptably low incidence of unnecessary therapy delivery in < 5% of ICD patients.