Abstract
Frequent premature ventricular contractions (PVCs) can lead to cardiomyopathy; it is unclear if there are abnormal myocardial mechanics operative in the PVC and non-PVC beats. The aim of this study was to investigate regional and global myocardial mechanics, including dyssynchrony, in patients with frequent PVCs. Fifty-six consecutive patients referred for PVC ablation were prospectively studied. During sinus rhythm (SR) and PVC beats, left ventricular (LV) global longitudinal strain (GLS), LV dyssynchrony (measured as the SD of time to peak GLS), and dyssynergy (measured as maximum regional strain minus minimum regional strain at aortic valve closure) were quantified using 2-dimensional strain echocardiography. GLS, dyssynchrony, and dyssynergy were compared in remote SR, pre-PVC SR, PVC, and post-PVC SR beats. In SR beats remote from the PVC, GLS was-17.3% ± 4%, dyssynchrony was 49 ± 14ms, and dyssynergy was22% ± 9%. Myocardial mechanics were significantly abnormal during PVCs compared with remote SR beats (GLS-7.7% ± 3% [P< 0.001], dyssynchrony 115 ± 37 milliseconds [P< 0.001], and dyssynergy 26% ± 10% [P<0.001]). There were significant mechanical abnormalities in the SR beat preceding the PVC, which demonstrated significantly lower LV strain (pre-PVC SR,-13% ± 4%; P< 0.001) and more dyssynchrony (pre-PVC SR, 63 ± 19 milliseconds; P< 0.001) compared with remote SR beats. Dyssynergy was significantly higher for pre-PVC SR and PVC beats compared with remote SR (pre-PVC SR, 25% ± 8% [P< 0.001]; PVC, 26% ± 10% [P< 0.001]). In patients with frequent PVCs, the SR beat preceding the PVC demonstrates significant mechanical abnormalities. This finding suggests that perturbations in cellular physiological processes such as excitation-contraction coupling may underlie the generation of frequent PVCs.
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