Bradyarrhythmias Associated with Oncologic Treatment—An Updated Review

Background/Objectives: Bradyarrhythmias are an under-recognized component of cancer therapy-related cardiovascular toxicity. As survivorship improves and exposure to targeted and immune therapies increases, clinicians increasingly face clinically relevant sinus node dysfunction and atrioventricular (AV) conduction disease that may interrupt otherwise effective oncologic treatment. We aimed to synthesize evidence on the incidence, phenotype, mechanisms, and management of bradyarrhythmias across major anticancer drug classes. Methods: We performed a narrative review of PubMed and major clinical guidelines, prioritizing prospective trials and large observational cohorts for incidence estimates, and case reports/series for phenotype and management details. Regulatory prescribing information and pharmacovigilance datasets were consulted to complement trial data. Evidence was organized by drug class and prototypical agents. Results: Bradyarrhythmias ranged from transient sinus bradycardia to high-grade atrioventricular block requiring pacing. The most severe phenotype was associated with immune checkpoint inhibitor-related myocarditis, whereas ALK inhibitors, thalidomide, antimetabolites—particularly 5-fluorouracil—and taxanes showed more reproducible signals for sinus bradycardia. Bradyarrhythmic events were also described with proteasome inhibitors, BTK (Bruton tyrosine kinase) inhibitors, anthracyclines, platinum compounds, high-dose cyclophosphamide, corticosteroids, and other agents, but the strength of evidence varied from regulatory or cohort-based data to isolated case reports. Conclusions: Bradyarrhythmias during cancer therapy are heterogeneous but clinically consequential. Recognition of class-specific patterns, proactive ECG/electrolyte monitoring, and context-specific management (e.g., drug interruption/dose modification, pacing when indicated, risk-factor control) can minimize therapy interruption while maintaining oncologic efficacy.