Work

Mapping the unseen: Programmed electrical stimulation to detect concealed conduction block

Year: 2025

Type: article

Abstract: Background Conduction blocks (CB) play an important role in the initiation and perpetuation of atrial fibrillation and may be masked due to its direction- or rate dependency. Objective We aim to investigate how the highest amount and most severe CB at the right atrium (RA) can be unmasked by delivering programmed electrical stimulation (PES) from various directions and at different frequencies. Methods High-resolution epicardial mapping was performed at the middle of RA on 40 patients during sinus rhythm (SR) and PES from the four sides of the mapping array at the average SR cycle length minus 50 ms (SR 50 ) and three different S1S2 trains (S1 400 , S2 300 , S2 250 or S2 200 ). CBA% was defined as the proportion of electrodes with a local conduction time >12 ms. CB severity was defined as the 95 th percentile of the conduction times over the lines of CB. Results CBA% increased from 0.6 [0-7.0] % during SR to 15.4 [12.3-19.2] % during S2 200 (P<0.001). CB severity increased from 18 [14-29] ms during SR to 46 [29-53] ms during S2 200 (p<0.001). PES increased CBA% over SR from 58% of patients during SR50 to 100% during S2200. The largest increase in CBA% occurred during S2 250 during pacing from perpendicular (+7.3 [0.5-10.8] %) and opposite (+7.4 [3.5-15.5] %) to the direction of SR. Conclusions Perpendicular pacing opposite to the direction of SR using premature stimuli is optimal for unmasking conduction block. PES may also reduce CB in patients who already exhibit complex activation patterns during SR.

Source: Heart Rhythm

DOI: 10.1016/j.hrthm.2025.10.053