Management of Atrial Flutter (AFL) Using Intrinsic Antitachycardia Pacing (iATP) Protocol.

Abstract

Background: Traditional management of atrial flutter (AFl) includes catheter ablation and pharmacological therapy. Antitachycardia pacing (ATP) has been explored as an alternative, with variable efficacy in terminating atrial arrhythmias. The intrinsic ATP (iATP) algorithm, previously validated for ventricular tachycardia, may offer enhanced efficacy in the atrium by leveraging programmed stimulation (PS).

Objective: This study evaluates the efficacy of iATP in terminating AFl and compares it to traditional ramp pacing protocols.

Methods: A prospective, randomized crossover trial was conducted in patients undergoing AFl ablation. Three ATP protocols were tested: (1) ramp pacing at 91% of tachycardia cycle length (TCL), (2) ramp pacing at 81% TCL, and (3) iATP, which incorporated PS with decrementing extra-stimuli. The primary endpoint was termination of AFl or acceleration to atrial fibrillation (AF), which was considered beneficial for rate control.

Results: Seventeen patients completed the protocol. AFl termination rates were 17.6% (Protocol 1), 20.5% (Protocol 2), and 38% (iATP). The iATP protocol also induced AF in 8 cases, compared to 1 and 4 cases in Protocols 1 and 2, respectively. The increased efficacy of iATP is attributed to its ability to introduce premature wavefronts into the excitable gap, enhancing termination rates.

Conclusion: iATP demonstrated superior efficacy in terminating AFl and accelerating it to AF compared to traditional ramp pacing. These findings support further exploration of iATP as a pacing-based intervention in atrial arrhythmia management. Future studies should assess its broader applicability in atypical AFl and AF.