Comparative Cardiac Adverse-Event Reporting Patterns Across Antineoplastic Therapeutic Classes: A Global Analysis Using WHO VigiAccess

Background/Objectives: Cardiac adverse-event reports for antineoplastic agents may differ across regulatory coding categories, affecting disproportionality estimates. We compared anthracyclines, human epidermal growth factor receptor 2 (HER2)-targeted agents, and vascular endothelial growth factor (VEGF) inhibitors. Methods: We analyzed aggregated World Health Organization VigiAccess data retrieved on March 23, 2026, for eight drugs in three classes. Medical Dictionary for Regulatory Activities (MedDRA) System Organ Class and cardiac Preferred Term distributions were described; reporting odds ratios (RORs) with 95% confidence intervals (CIs) were calculated using a restricted antineoplastic comparator cohort. Pairwise within-cohort comparators and cardiac/vascular outcomes were explored; an external database-wide comparison was not feasible. Results: Across 389,068 drug-specific report observations, anti-HER2 agents had the highest proportion classified under Cardiac disorders (10.43%) and the strongest class-level ROR (2.04; 95% CI 1.99–2.10); trastuzumab had the highest drug-level ROR (2.22; 2.16–2.29). Anthracyclines contributed the most cardiac reports (11,273), whereas anti-VEGF agents showed greater proportional reporting in vascular disorders (10.86%) and prominent myocardial infarction reports among cardiac Preferred Terms. Exploratory analyses demonstrated sensitivity to comparator composition and outcome definition. Conclusions: Reporting patterns varied across classes, but these findings do not establish incidence, causality, comparative clinical risk, or independent grounds for changing surveillance protocols.