TOP2B and cardiac arrhythmia: Radiotherapy induces oxidative stress (OS) and matrix remodeling, which alters the cardiac microvascular and macrovascular environment and induces coronary artery disease, myocardial fibrosis, and cardiomyopathy, valvular disease, pericardial disease, and arrhythmias (9, 10); chemotherapies can cause cardiotoxicity through OS, lipid peroxidation, and inhibition of topoisomerase IIβ (Top2β), leading to cardiomyocytes (CMs) damage (11).