Background Several studies have shown improved outcomes in closed compared with open medical and surgical intensive care units. However, very little is known about the ideal organizational structure in the modern cardiac intensive care unit (CICU). Methods and Results We retrospectively reviewed consecutive unique admissions (n=3996) to our tertiary care CICU from September 2013 to October 2017. The aim of our study was to assess for differences in clinical outcomes between an open compared with a closed CICU. We used multivariable logistic regression adjusting for demographics, comorbidities, and severity of illness. The primary outcome was in‐hospital mortality. We identified 2226 patients in the open unit and 1770 in the closed CICU. The unadjusted in‐hospital mortality in the open compared with closed unit was 9.6% and 8.9%, respectively ( P =0.42). After multivariable adjustment, admission to the closed unit was associated with a lower in‐hospital mortality (odds ratio [OR], 0.69; 95% CI: 0.53–0.90, P =0.007) and CICU mortality (OR, 0.70; 95% CI, 0.52–0.94, P =0.02). In subgroup analysis, admissions for cardiac arrest (OR, 0.42; 95% CI, 0.20–0.88, P =0.02) and respiratory insufficiency (OR, 0.43; 95% CI, 0.22–0.82, P =0.01) were also associated with a lower in‐hospital mortality in the closed unit. We did not find a difference in CICU length of stay or total hospital charges ( P >0.05). Conclusions We found an association between lower in‐hospital and CICU mortality after the transition to a closed CICU. These results may help guide the ongoing redesign in other tertiary care CICUs.