Purkinje activity influenced the morphology and timing of PVCs that triggered ventricular fibrillation (VF) after acute myocardial infarction (AMI). A multicentre retrospective study published in EP Europace evaluated the electrophysiological characteristics of Purkinje potentials and their relationship with the cardiac conduction system.

The analysis included 53 patients with acute or subacute myocardial infarction who underwent catheter ablation for VF-triggering PVCs. The mean age was 66 ± 11 years, and 13% were female. A total of 67 PVCs were analysed. The mean PVC width was 157 ± 42 ms, and 87% of PVCs demonstrated right bundle branch block (RBBB) morphology.

Purkinje potentials preceded 72% of PVCs, with a mean interval of 68 ± 42 ms. PVCs with preceding Purkinje potentials had a narrower QRS duration than those without Purkinje activity (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 the Purkinje potential to PVC onset (P < 0.0001). Retrograde conduction from the Purkinje network with subsequent anterograde conduction through the right bundle branch was identified in 9% of cases. In these PVCs, the coupling interval from the preceding sinus beat was longer (391 ± 12 ms vs 467 ± 34 ms; P = 0.041).

These findings show that Purkinje potentials have distinct electrophysiological properties that influence QRS duration and PVC timing in VF-triggering beats after AMI.