Impact of atrial programmed electrical stimulation techniques on unipolar electrogram morphology.

Introduction: Intra-atrial conduction abnormalities are associated with the development of atrial fibrillation (AF) and cause morphological changes of the unipolar atrial electrogram (U-AEGM). This study examined the impact of different atrial programmed electrical stimulation (APES) protocols on U-AEGM morphology to identify the most optimal APES protocol provoking conduction abnormalities.

Methods: APES techniques (14 protocols) were applied in 30 patients referred for an electrophysiology study, consisting of fixed rate, extra, and decremental stimuli at different frequencies. U-AEGM morphologies including width, amplitude, and fractionation for patients without (control group) and with a history of AF (AF group) were examined during APES. In addition, sinus rhythm (SR) U-AEGMs preceding different APES protocols were compared to evaluate the morphology stability over time.

Results: U-AEGM morphologies during SR before the APES protocols were comparable (all P > .396). Atrial refractoriness was longer in the AF group compared to the control group (298 ± 48 vs 255 ± 33 ms; P ≤ .020), but did not differ between AF patients with and without amiodarone therapy (278 ± 48 vs 311 ± 40 ms; P ≥ .126). Compared to the initial SR morphology, U-AEGM width, amplitude, and fractionation changed significantly during the 14 different APES protocols, particularly in the AF group. In both groups, U-AEGM changes in morphology were most pronounced during fixed-rate stimulation with extra stimuli (8S1-S2 = 400-250 ms).

Conclusion: APES results in significant changes in U-AEGM morphology, including width, amplitude, and fractionation. The impact of APES differed between APES sequence and between patients with and without AF. These findings suggest that APES could be useful to identify AF-related conduction abnormalities in the individual patient.