PO-02-183 ATRIO-VENTRICULAR DISSOCIATION IN PREMATURE VENTRICULAR CONTRACTION WITH DIFFERENT COUPLING INTERVALS

Abstract

The pathophysiology of Premature ventricular contraction (PVC) induced cardiomyopathy (PVC-CM) remains unclear. AV dissociation (AVD) during PVCs is known as atrial contraction at the time of the PVC. AVD has been implicated as a potential trigger and predictor of PVC-CM, especially early AVD since it results in an increase in LA pressure due to mitral valve closure. The goal of this study was to assess AVD during short- and long-coupled PVCs, and its correlation with the development of PVC-CM. Thirty-one canines underwent implantation of 1) a modified pacemaker to reproduce RV apical PVCs and 2) a telemetry device with a bipole implanted in the LA appendage and RV to record local electrograms and assess AVD during PVCs. Animals were randomized to short-coupled (200ms, n=14), long-coupled (330ms, n=8) bigeminal PVCs, or no PVCs (sham, n=11). AVD was categorized as absent (no P wave during QT interval), early (P wave present between QRS and the peak of the T wave of PVC), or late AVD (P wave between peak and end of T wave of PVC). AVD for four 1-minute segments (6 AM, 12 PM, 6 PM, and 12 AM) for 24 hours and LV ejection fraction were assessed after weeks 1, 4, and 12 of bigeminal PVCs. Ponemah software was used for HR analysis to calculate the minimum, maximum, and average HR and PVC burden. Overall AVD was similar between short- and long-coupled PVCs throughout the 12 weeks (Panel A). Short-coupled PVCs had 35% and 21% of early and late AVD, respectively and no AVD in 44%. Long-coupled PVCs had 50% and 13% of early and late AVD, respectively, without AVD in 37% (Panel B). The early AVD was significantly higher in long-coupled PVCs compared to short-coupled PVCs (50% vs. 35%, Two-Way ANOVA P<0.001), while late AVD was higher in short-coupled PVCs compared to long-coupled PVCs (22% vs. 13%, Two-Way ANOVA, p=0.018) (Panel A &C). Neither short nor long-coupled PVCs showed a significant correlation between AVD and reduction in LVEF at 12 weeks (r=0.09, r=0.06 with p=0.5, p=0.8, respectively). The short- and long-coupled PVCs had increased HR relative to the sham groups (121 vs. 105 vs. 83, Two-Way ANOVA p<0.001). Moreover, HR was significantly higher in short-coupled PVCs than in Long-coupled PVCs (121 vs. 105, Two-Way ANOVA p< 0.001). Early AVD is more pronounced in long-coupled PVCs. AVD does not predict the development of PVC-CM regardless of PVC coupling interval, suggesting that AVD does not play a role in the pathophysiology of PVC-CM.