Electrophysiological characteristics of Purkinje potentials and the conduction system in premature ventricular contractions triggering ventricular fibrillation after myocardial infarction

Catheter ablation for premature ventricular contractions (PVCs) triggering ventricular fibrillation (VF) after acute myocardial infarction (AMI) has proven effective, with Purkinje potentials often serving as the target. However, the electrophysiological features of Purkinje potentials and their relationship with the conduction system in VF-triggering PVCs remain unclear.

This multicentre retrospective study analysed patients who underwent catheter ablation for VF-triggering PVCs during the acute or subacute phase of AMI. Characteristics of Purkinje potentials, including retrograde conduction from the Purkinje network and subsequent anterograde conduction to the right bundle branch (RB), were evaluated for PVC morphology.

Fifty-three patients (mean age 66±11 years; 13% female) with 67 VF-triggering PVCs were analysed. The mean PVC width was 157 ± 42 ms, with 87% showing RB branch block morphology. Purkinje potentials preceded 72% of PVCs (mean interval 68 ± 42 ms). PVCs with preceding Purkinje potentials had narrower QRS duration (145 ± 26 ms vs. 198 ± 57 ms, P < 0.0001). The coupling interval from the preceding sinus beat was inversely correlated with the interval from Purkinje potential to PVC onset (P < 0.0001). Retrograde Purkinje conduction with subsequent anterograde RB conduction was identified in 9%. In these cases, the coupling interval from the preceding sinus beat was longer (391 ± 12 ms vs. 467 ± 34 ms, P = 0.041).

Purkinje potentials show distinct properties that influence both QRS duration and PVC timing. The presence of preceding Purkinje potentials together with QRS duration may help guide ablation strategies. In rare cases, Purkinje activity conducts retrogradely from the left bundle and anterogradely through the RB, modifying PVC morphology.