Background Frequent premature ventricular contractions (PVC) have been associated with PVC-induced cardiomyopathy (CM) in some patients. Objective Understand the cardiac consequences of different PVC burden and minimum burden required to induce LV dysfunction. Methods RV apical PVCs at a coupling interval of 240ms were introduced at different PVC burden in 9 mongrel canines. A stepwise increase in PVC burden was implemented every 8 weeks from 0% (baseline), 7%, 14%, 25%, 33% to 50% using our premature pacing algorithm. Echocardiogram and 24-hr Holter were obtained at 4- and 8-week period at each PVC burden with a single blinded reader assessing all echocardiographic parameters including speckle tracking imaging (GE EchoPAC). CM was defined as LVEF < 50% or a decrease >10% points. IL-6 and pro-BNP levels were obtained at the end of each PVC burden. Results LVEF±SD (mean heart rate ± SD) for 0%, 7%, 14%, 33%, and 50% at 8 weeks for each PVC burden were 57±2.9% (85±13bpm); 54.4±3% (81±10bpm); 53.3±5% (77±12bpm); 51.1±4.2% (79±14bpm); 47.7±3.8% (80±14bpm); 44.7±1.9% (157±43bpm). PVC-induced CM was present in 11.1%, 44.4%, and 100% of animals with 25%, 33% and 50% PVC burden, respectively. E/A ratio and radial strain decreased while LA size increased beyond 33% PVC burden. No changes in pro-BNP and IL-6 levels were noted at any PVC burden. Conclusion LV systolic function (LVEF, and radial strain) declined linearly as PVC burden increased. PVC-induced CM developed in some canines with 25% and 33% PVC burden, but developed in all animals with 50% PVC burden.

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ICD lead malfunction can occur following LVAD implantation but may improve over time. Intraoperative RV sensing and HV impedance changes were not detected until after weaning from cardiopulmonary bypass, suggesting the mechanism of RV lead malfunction may be related to LV unloading and concomitant leftward septal shift. A conservative approach is warranted in many patients with ICD parameter changes after LVAD implantation because parameter abnormalities may improve over time. (Implantable Cardioverter Defibrillator (ICD) Function During Ventricular Assist Device (VAD) Implantation; NCT01576562).

Increased utilization of cardiovascular implantable electronic devices (CIED) has seen a corresponding rise in related infections. Non-tuberculosis mycobacteria (NTM) are rarely the cause. Treatment involves susceptibilities, antimicrobials, and device removal. This study presents a patient who underwent a biventricular implantable cardioverter defibrillator upgrade with a multi-drug resistant Mycobacterium fortuitum located at the pocket site and a lead infection.

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