Efficacy of atrial antitachycardia functions for treating atrial fibrillation: observations in patients with a dual-chamber defibrillator.

In patients with conventional indication for ICD implantation, atrial fibrillation may occur in more than 50% during the life-span of the device and may lead to severe adverse events. Dual chamber defibrillators with atrial antitachycardia functions, including prevention algorithms, arrhythmia detection capability and atrial therapy options (antitachy pacing and cardioversion) have been recently introduced. The aim of this review is to examine the effectiveness of these new devices and to identify patients who may benefit. We recently studied 112 patients who received the device because of life-threatening ventricular arrhythmias. Fifty-five percent of them had atrial fibrillation prior to implantation. During the follow-up (one year on average), 27% had at least one episode of sustained atrial tachyarrhythmia. Effectiveness of atrial antitachy pacing was 71% on regular atrial tachycardia and 36% on irregular atrial tachyarrhythmias. Atrial shock efficacy was over 90% when adequately programmed. Interestingly, near half of the episodes started as regular atrial tachycardia and accelerated and became less organized in few minutes. Early delivery of antitachy pacing may increase success rate and decrease the need for atrial shock. Furthermore, it may prevent atrial remodeling and reduce atrial fibrillation burden. Based on our experience, we recommend that all patients with a class I indication for defibrillator implantation (related to risk of ventricular arrhythmias) who have a history of or are at risk of developing atrial tachyarrhythmias should receive a dual chamber defibrillator equipped with atrial antitachycardia functions. Furthermore, patients either with a history of heart failure, with poor functional capacity (functional class III or IV), depressed left ventricular ejection fraction, a need for monitoring of atrial rhythm, or in whom there is some concern about appropriate detection of ventricular arrhythmias, may benefit from a single device capable of managing ventricular and supraventricular arrhythmias.