Abstract 4364406: Basal Septal Premature Ventricular Contractions are associated with Complete Heart Block Development: Case Series

Background: Premature ventricular contractions (PVCs) are one of the most common arrhythmias and can be associated with increased risk of mortality and major cardiovascular events including PVC-induced cardiomyopathy, ventricular fibrillation, and conduction system diseases. Hypothesis: This study seeks to identify electro-anatomical association of PVC origin in patients with elevated PVC burden who eventually develop Complete Heart Block (CHB). Methods: This retrospective case series included patients with cardiac magnetic resonance (CMR) imaging with elevated PVC burden (>1% burden, identified by Holter or implanted device). We also evaluated patients who had electrophysiology study confirmed location of PVCs to correlate morphological characteristics and electroanatomic localization. Records from 4217 patients between 2009 and 2023 were screened. Results: A total of 4 patients were identified with elevated PVC burden prior to the development of CHB, without reported septal scar on CMR. Each had a single PVC morphology which was left bundle branch morphology, V3/V4 transition, with left inferior axis with R or Rs morphology in lead 1 (Figure 1A), and all developed infrahisian CHB. PVC characteristics most closely matched PVCs originating from the right coronary cusp (RCC) and basal septum. Careful review of the CMR images in 2/4 (50%) patients found an area of focal fibrosis at the basal septum at the junction RCC and medial papillary muscle of the right ventricle (Figure 1B).In the other 2 patients, this area was not well imaged. Conclusion: We identified a consistent PVC morphology in patients who developed infrahisian CHB with imaging correlate of focal fibrosis at the site where the His bundle and proximal left and right bundles traverse (Figure 1C). This focal area of scar is in a site that is difficult to image by CMR, and often only visualized in one view and hence easily missed. This study demonstrates the need for careful electro-anatomic-imaging correlation in patients with frequent PVCs of this morphology.