Anti-CTLA-4 agents were not associated with over-reporting frequencies of reporting arrhythmias [ROR: 0.62 (0.57–0.67)], consistent with previous findings showing that anti-CTLA-4 was not associated with risk of reporting pericardial toxicities and less susceptible to myocarditis (Zhou et al., 2019; Ma et al., 2021). Here, CTLA4 is linked to cardiac arrhythmia.