Electrical cardioversion (ECV) is recommended for rhythm control in patients with atrial arrhythmia; yet, ECV use and outcomes in contemporary practice are unknown. We reviewed all nonemergent ECVs for atrial arrhythmias at a tertiary care center (2010 to 2013), stratifying patients by transesophageal echocardiography (TEE) use before ECV and comparing demographics, history, vitals, and laboratory studies. Outcomes included postprocedural success and complications and repeat cardioversion, rehospitalization, and death within 30 days. Overall, 1,017 patients underwent ECV, 760 (75%) for atrial fibrillation and 240 (24%) for atrial flutter; 633 underwent TEE before ECV and 384 did not. TEE recipients were more likely to be inpatients (74% vs 44%, p <0.001), have higher mean CHADS₂ scores (2.6 vs 2.4, p = 0.03), and lower mean international normalized ratios (1.2 vs 2.1, p <0.001). Overall, 89 patients (8.8%) did not achieve sinus rhythm and 14 experienced procedural complications (1.4%). Within 30 days, 80 patients (7.9%) underwent repeat ECV, 113 (11%) were rehospitalized, and 14 (1.4%) died. Although ECV success was more common in patients who underwent TEE before ECV (77% vs 68%, p = 0.01), there were no differences in 30-day death or rehospitalization rates (11.1% vs 13.0%, p = 0.37). In multivariate analyses, higher pre-ECV heart rate was associated with increased rehospitalization or death (adjusted hazard ratio 1.15/10 beats/min, 95% confidence interval 1.07 to 1.24, p <0.001), whereas TEE use was associated with lower rates (adjusted hazard ratio 0.58, 95% confidence interval 0.39 to 0.86, p = 0.007). In conclusion, failures, complications, and rehospitalization after nonemergent ECV are common and associated more with patient condition than procedural characteristics. TEE use was associated with better clinical outcomes.