Proarrhythmic effects from competitive atrial pacing and potential programming solutions.

Area of Science:

• Electrophysiology
• Medical Device Technology
• Cardiac Pacing

Background:

• Programmed long AV delays and intrinsic first-degree AV block can elevate the risk of competitive atrial pacing (CAP).
• Devices lacking CAP avoidance algorithms are particularly susceptible.
• This poses a risk for device-induced atrial proarrhythmia.

Purpose of the Study:

• To investigate the incidence and mechanisms of competitive atrial pacing (CAP).
• To evaluate strategies for preventing and managing CAP-induced mode switch episodes.
• To identify patient populations and device settings associated with increased CAP risk.

Main Methods:

• Clinical follow-up of 23 patients with CAP-induced mode switch episodes (September 2013 - August 2019).
• Interventions included shortening postventricular atrial refractory period (PVARP) or postventricular atrial blanking period (PVAB), and mode changes to AAI or DDI.
• Rate response inactivation was performed in a subset of patients with sensor-driven pacing.

Main Results:

• CAP was identified in 23 patients (22 St Jude Medical, 1 Boston Scientific).
• Atrial fibrillation (AF) was induced in 12 patients (52%), with durations ranging from 10 seconds to over 28 hours.
• In one patient, CAP-induced AF led to ventricular fibrillation, syncope, and shock. Shortening AV delays and PVARP were ineffective. Inactivating rate response resolved AF in 3/7 patients. AAI(R) pacing resolved CAP in two patients with intact AV conduction.

Conclusions:

• CAP predominantly occurs during sensor-driven atrial pacing when intrinsic atrial events coincide with the PVARP.
• Inactivating activity sensors or switching to atrial-based pacing modes (AAI/R) effectively prevents device-induced atrial proarrhythmia.
• A dedicated corrective algorithm is necessary to avoid CAP-induced proarrhythmia.