Using Floating Atrial Electrodes to Combat the Rising Tide of Inappropriate Defibrillator Therapies

Abstract

Despite various implantable defibrillator algorithms and strategies used to improve discrimination between potentially life-threatening ventricular arrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]) and more benign supraventricular tachycardias (SVTs), this remains a problem. In addition to significant discomfort and impairment of quality of life, there is some suggestion that shocks may increase mortality.1 Recording atrial intracardiac electrograms during arrhythmic episodes would be expected to improve our ability to discriminate tachycardias and thus reduce the number of inappropriate shocks. It may also lead to the diagnosis of otherwise unsuspected atrial arrhyhmias that may require specific therapy, such as anticoagulation therapy for patients with atrial flutter or atrial fibrillation (AF). Article see p 56 The evidence available so far, however, does not clearly demonstrate that atrial electrograms reduce inappropriate shocks.2–7 Although some studies performed in patients with a dual-chamber device have shown a reduction in inappropriate detection, inappropriate shocks also were avoided in the single-chamber detection arm by using anti tachycardia pacing.2 In addition, placement of an atrial lead is associated with a risk of lead dislodgement (≈4.5%) and increased procedural and fluoroscopy times compared to a single-chamber defibrillator. Thus, there currently is no strong evidence to support the addition of an atrial lead for the sole purpose of SVT discrimination and reducing implantable cardioverter-defibrillator (ICD) shocks.8 Using a single-pass VDD defibrillator lead holds the promise of offering atrial electrograms without the additional risks and procedural time related to implantation of a separate atrial lead. Similar lead designs with integrated atrial electrodes have been used in VDD pacemakers.9 In a study published by Sticherling et al in this issue of Circulation: Arrythmia and Electrophysiology , the ADRIA (Study to Verify Proper Detection of Supraventricular Tachyarrhythmia With Single-Lead Dual-Chamber Implantable Cardioverter-Defibrillators) study, the authors investigated the use …