Low-Energy Multistage Atrial Defibrillation Therapy Terminates Atrial Fibrillation With Less Energy Than a Single Shock

BACKGROUND—Implantable device therapy of atrial fibrillation (AF) is limited by pain from high-energy shocks. We developed a low-energy multistage defibrillation therapy and tested it in a canine model of AF. METHODS AND RESULTS—AF was induced by burst pacing during vagus nerve stimulation. Our novel defibrillation therapy consisted of 3 stagesstage (ST) 1 (1–4 low-energy biphasic [BP] shocks), ST2 (6–10 ultralow-energy monophasic [MP] shocks), and ST3 (antitachycardia pacing). First, ST1 testing compared single or multiple MP and BP shocks. Second, several multistage therapies were testedST1 versus ST1+ST3 versus ST1+ST2+ST3. Third, 3 shock vectors were comparedsuperior vena cava to distal coronary sinus, proximal coronary sinus to left atrial appendage, and right atrial appendage to left atrial appendage. The atrial defibrillation threshold (DFT) of 1 BP shock was