EDITOR’S PERSPECTIVE What We Already Know about This Topic The incidence of major adverse cardiac events after electroconvulsive therapy is not known What This Article Tells Us That Is New Major adverse cardiac events and death after electroconvulsive therapy are infrequent and occur in about 1 of 50 patients and after about 1 of 200 to 500 electroconvulsive therapy treatments Background Cardiac events after electroconvulsive therapy have been reported sporadically, but a systematic assessment of the risk is missing. The goal of this study was to obtain a robust estimate of the incidence of major adverse cardiac events in adult patients undergoing electroconvulsive therapy. Methods Systematic review and meta-analysis of studies that investigated electroconvulsive therapy and reported major adverse cardiac events and/or mortality. Endpoints were incidence rates of major adverse cardiac events, including myocardial infarction, arrhythmia, pulmonary edema, pulmonary embolism, acute heart failure, and cardiac arrest. Additional endpoints were all-cause and cardiac mortality. The pooled estimated incidence rates and 95% CIs of individual major adverse cardiac events and mortality per 1,000 patients and per 1,000 electroconvulsive therapy treatments were calculated. Results After screening of 2,641 publications and full-text assessment of 284 studies, the data of 82 studies were extracted (total n = 106,569 patients; n = 786,995 electroconvulsive therapy treatments). The most commonly reported major adverse cardiac events were acute heart failure, arrhythmia, and acute pulmonary edema with an incidence (95% CI) of 24 (12.48 to 46.13), 25.83 (14.83 to 45.00), and 4.92 (0.85 to 28.60) per 1,000 patients or 2.44 (1.27 to 4.69), 4.66 (2.15 to 10.09), and 1.50 (0.71 to 3.14) per 1,000 electroconvulsive therapy treatments. All-cause mortality was 0.42 (0.11 to 1.52) deaths per 1,000 patients and 0.06 (0.02 to 0.23) deaths per 1,000 electroconvulsive therapy treatments. Cardiac death accounted for 29% (23 of 79) of deaths. Conclusions Major adverse cardiac events and death after electroconvulsive therapy are infrequent and occur in about 1 of 50 patients and after about 1 of 200 to 500 electroconvulsive therapy treatments.