How, Why, and When May Atrial Defibrillation Find a Specific Role in Implantable Devices? A Clinical Viewpoint

Abstract

This viewpoint article discusses the potential for incorporation of atrial defibrillation capabilities in modern multi-chamber devices. In the late 1990s, the possibility of using shock-only therapy to treat selected patients with recurrent atrial fibrillation (AF) was explored in the context of the stand-alone atrial defibrillator. The failure of this strategy can be attributed to the technical limitations of the stand-alone device, low tolerance of atrial shocks, difficulties in patient selection, a lack of predictive knowledge about the evolution of AF, and, last but not least, commercial considerations. An open question is how atrial defibrillation capability may now assume a specific new role in devices implanted for sudden death prevention or cardiac resynchronization. For patients who already have indications for implantable devices, device-based atrial defibrillation appears attractive as a "backup" option for managing AF when preventive pharmacological/electrical measures fail. This and several other personalized hybrid therapeutic approaches await exploration, though assessment of their efficacy is methodologically challenging. Achievement of acceptance by patients is an essential premise for any updated atrial defibrillation strategy. Strategies that are being investigated to improve patient tolerance include waveform shaping, pharmacologic modulation of pain, and patient-activated defibrillation (patients might also perceive the problem of discomfort somewhat differently in the context of a backup therapy). The economic impact of implementing atrial defibrillation features in available devices is progressively decreasing, and financial feasibility need not be a major issue. Future studies should examine clinically relevant outcomes and not be limited (as occurred with stand-alone defibrillators) to technical or other soft endpoints.

Atrial Fibrillation Therapy in Patients with a CRT Defibrillator with Wireless Telemetry

“…Atrial shock therapy with or without sedation has been demonstrated to be very efficacious and surprisingly well tolerated in patients with single‐chamber, dual‐chamber, or atrial defibrillators 15–18 . However, ICD‐based atrial shock therapy has not been extensively studied in patients with CRT defibrillators 12,19–21 …”

“…Atrial shock therapy with or without sedation has been demonstrated to be very efficacious and surprisingly well tolerated in patients with single-chamber, dual-chamber, or atrial defibrillators. [15][16][17][18] However, ICD-based atrial shock therapy has not been extensively studied in patients with CRT defibrillators. 12,[19][20][21] This study therefore was performed to analyze the safety of the Medtronic Concerto CRT-D system (Medtronic, Inc., Minneapolis, MN, USA) and the efficacy of the atrial shock therapy in patients with an indication for a CRT-D. We defined efficacy as the percentage of acute conversion of atrial fibrillation.…”

Painless Shock Therapy: More Than Just an Attempt to Square the Circle?

“…The pain related to electrical shocks delivered by a cardioverter defibrillator (ICD) is usually poorly tolerated by patients and constitutes one of the main limitations of defibrillation therapy for ventricular or atrial tachyarrhythmias 1,2 . At the same time, shock therapy has the unique characteristic of providing a highly effective “rescue” measure to restore a normal rhythm 2 .…”

“…The pain related to electrical shocks delivered by a cardioverter defibrillator (ICD) is usually poorly tolerated by patients and constitutes one of the main limitations of defibrillation therapy for ventricular or atrial tachyarrhythmias 1,2 . At the same time, shock therapy has the unique characteristic of providing a highly effective “rescue” measure to restore a normal rhythm 2 . The role of the ICD is enhanced in all clinical settings where pharmacological prevention strategies are of limited efficacy, such as in patients at risk of sudden death due to malignant ventricular tachyarrhythmias or in heart failure patients experiencing atrial fibrillation (AF) recurrences 1–3 …”

“…At the same time, shock therapy has the unique characteristic of providing a highly effective “rescue” measure to restore a normal rhythm 2 . The role of the ICD is enhanced in all clinical settings where pharmacological prevention strategies are of limited efficacy, such as in patients at risk of sudden death due to malignant ventricular tachyarrhythmias or in heart failure patients experiencing atrial fibrillation (AF) recurrences 1–3 …”