Concerning reports of cardiac arrhythmias, a significant increased ROR was found for anti-PD-1 monotherapy [ROR 1.11 (1.03–1.21), IC025 0.06] and anti-PD-L1 monotherapy [ROR 1.37 (1.27–1.49), IC025 0.29], with the exception of anti-CTLA-4 monotherapy [ROR 0.62 (0.57–0.67), IC025 −1.21]. This evidence concerns the gene CTLA4 and cardiac arrhythmia.