Diagnostic gain of cardiac MR in patients with premature ventricular complexes and structurally normal hearts on echocardiography

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: Public Institution(s). Main funding source(s): KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway BACKGROUND: An important part of the diagnostic evaluation of patients with premature ventricular complexes (PVCs) is to identify underlying cardiac disease. The majority of these patients referred to catheter ablation have PVCs with inferior axis and left bundle branch block morphology (I-LBBB). Although this is the most common morphology in patients with idiopathic PVCs, cardiac magnetic resonance (CMR) is recommended to exclude potential other underlying pathology. However, the diagnostic gain of CMR in patients with I-LBBB PVCs is uncertain. PURPOSE: The purpose of this study was to explore the prevalence of cardiac abnormalities identified by CMR in patients with I-LBBB PVCs evaluated for catheter ablation without signs of underlying cardiac disease from resting ECG, stress test, or echocardiography. METHODS: We retrospectively collected data from consecutive patients with I-LBBB PVCs evaluated for catheter ablation at our tertiary referral centre from 2011 to 2022. We included patients with normal ECG and stress test, and no evidence of functional or structural heart disease by echocardiography. We categorized CMR examinations as normal or as having signs of functional or structural abnormalities. RESULTS: We identified a total of 63 patients with I-LBBB PVCs evaluated for catheter ablation, with no signs of underlying conditions from sinus rhythm ECG, stress test or echocardiography. All were studied by CMR at our institution. The median age was 49 years (IQR 36-61), and 39 were females (62 %). The maximum PVC burden recorded in each patient prior to referral was 20 % (IQR 11-29.5). Left ventricular (LV) ejection fraction by echocardiography was 56±4 %. CMR was normal in 52 patients (83 %), while functional or structural abnormalities were detected in 11 patients (17 %). These abnormalities comprised reduced LV systolic function (2 patients), dilated right ventricle (2 patients), dilated LV (1 patient), ventricular septal defect (2 patients), non-compaction cardiomyopathy (1 patient), mitral annular disjunction (2 patients), tricuspidal annular disjunction (1 patient), and myocardial fibrosis by late contrast enhancement (3 patients). CONCLUSIONS: In patients with I-LBBB PVCs evaluated for catheter ablation, and with no signs of underlying pathology from standard diagnostic work-up, CMR detected abnormalities in 17 %. These results support the routine use of CMR in the evaluation of patients with I-LBBB PVCs referred for catheter ablation.