Efficacy and Safety of an Extravascular Implantable Cardioverter–Defibrillator

This prospective, multicenter, nonrandomized trial evaluated the safety and efficacy of a novel extravascular implantable cardioverter-defibrillator (ICD) that uses a substernal lead for pacing and defibrillation. A total of 356 patients were enrolled, with implantation attempted in 316. Among 302 patients who completed the defibrillation protocol, 98.7% had successful arrhythmia termination. At 6-month follow-up, the Kaplan-Meier estimate of freedom from major system- or procedure-related complications was 92.6%, exceeding safety benchmarks. The device enabled pause-prevention and antitachycardia pacing, though pacing sensation led to therapy deactivation in select patients. Antitachycardia pacing terminated 70% of monomorphic ventricular tachyarrhythmia episodes; shock conversion efficacy was 100% for discrete arrhythmias. Inappropriate shocks occurred in 9.7% of patients, mainly due to atrial oversensing. Device revisions were infrequent; eight systems were explanted without replacement. The study supports extravascular ICDs as a safe and effective alternative to transvenous and subcutaneous systems, with the added benefit of pacing and reduced defibrillation energy

This prospective, multicenter, nonrandomized trial evaluated the safety and efficacy of a novel extravascular implantable cardioverter-defibrillator (ICD) that uses a substernal lead for pacing and defibrillation. A total of 356 patients were enrolled, with implantation attempted in 316. Among 302 patients who completed the defibrillation protocol, 98.7% had successful arrhythmia termination. At 6-month follow-up, the Kaplan-Meier estimate of freedom from major system- or procedure-related complications was 92.6%, exceeding safety benchmarks. The device enabled pause-prevention and antitachycardia pacing, though pacing sensation led to therapy deactivation in select patients. Antitachycardia pacing terminated 70% of monomorphic ventricular tachyarrhythmia episodes; shock conversion efficacy was 100% for discrete arrhythmias. Inappropriate shocks occurred in 9.7% of patients, mainly due to atrial oversensing. Device revisions were infrequent; eight systems were explanted without replacement. The study supports extravascular ICDs as a safe and effective alternative to transvenous and subcutaneous systems, with the added benefit of pacing and reduced defibrillation energy