Electrocardiographic Characteristics of Escape Rhythm During Complete Atrioventricular Block After Transcatheter Aortic Valve Replacement.

Background: Complete atrioventricular block (CAVB) following transcatheter aortic valve replacement (TAVR) is primarily attributed to mechanical compression of the penetrating or branching portions of the His bundle, and less commonly, the atrioventricular (AV) node. This study aimed to characterize the electrocardiographic features of stable escape rhythms (ERs) occurring during CAVB after TAVR. Methods: This retrospective study analyzed 12-lead electrocardiograms (ECGs) obtained at three time points: before TAVR (ECG 1), after TAVR but before CAVB (ECG 2), and during CAVB (ECG 3). The ERs on ECG 3 were classified as AV junctional if the rate was 40-60 beats per minute (bpm) and, compared with ECG 2, if the QRS morphology matched in ≥10/12 leads, the QRS duration differed by <10 ms, and the frontal QRS axis differed by <30°. The ERs not meeting these criteria were considered ventricular in origin. Three patients with ERs <40 bpm but matching AV junctional morphology were included in the AV junctional group. ECG 2 was unavailable in 12 patients. Results: Among the 58 patients included, 56.9% had no conduction abnormalities on baseline ECG 1. Following TAVR (ECG 2), left and right bundle branch blocks were observed in 69.6% and 17.4% of the patients, respectively. During CAVB (ECG 3), the ERs were presumed to originate from the AV junction in 23 patients (39.6%), from the ventricles in 28 (48.3%), and had an undetermined origin in 7 (12.1%). Conclusions: Consistent with the anatomical regions commonly affected by the prosthetic aortic valve during TAVR, a substantial proportion of patients exhibited ERs likely originating from the AV junction, suggesting a potential role for conduction system pacing in managing CAVB in this setting of patients.