Temporal and Spatial Changes of Proarrhythmic Substrate in Premature Ventricular Contraction–Induced Cardiomyopathy

The changes in proarrhythmic substrates and malignant ventricular arrhythmia mechanisms caused by premature ventricular contraction-induced cardiomyopathy (PVCCM) remain unclear.The goal of this study was to establish the electrophysiological mechanism of how high-load PVC causes malignant arrhythmia.Thirteen swine were exposed to 50% paced PVC from the right ventricular apex for 12 weeks (PVCCM, n = 6) and no pacing for 12 weeks (control, n = 7). Cardiac function was quantified biweekly with echocardiography. Computed tomography scans and electrophysiological examinations were performed monthly to dynamically evaluate the changes in the cardiac structure and the arrhythmogenic substrate.The decreases in the cardiac function and ventricular enlargement in the PVCCM group were significant after 12 weeks of PVC stimulation compared with the control group (P < 0.001). Electrophysiological examination found that the ventricular effective refractory period dispersion (0.071 ± 0.008), area of the low-voltage zone (9.41 ± 1.55 cm2), and malignant ventricular arrhythmia inducibility (33.3%) of the PVCCM group increased significantly at week 8 after pacing (P < 0.001 vs the control group); these changes slowed down after 8 weeks. Moreover, the distribution of the low-voltage zone presented obvious spatial heterogeneity, especially in the anterior wall of the right ventricle, accompanied by delayed activation in the sinus rhythm (67 ± 13 milliseconds). Consistently, the proportion of ventricular fibrosis- and expression-related proteins were significantly increased in the PVCCM group (P < 0.001), especially in the right ventricle. Moreover, proteomic analysis confirmed the spatial profile of these fibrotic changes in the PVCCM group.High-burden PVC can cause significant temporal and spatial heterogeneity changes in proarrhythmic substrates, which are potentially related to the upregulation of calcium signaling caused by asynchronous activation.