Prior studies have suggested that patients with acute myocardial infarction (AMI) who are admitted during off-hours (weekends, nights and holidays) have higher mortality when compared with patients admitted during regular hours.

We analyzed consecutive patients with AMI (ST-elevation myocardial infarction [STEMI] and non-STEMI) who were treated with percutaneous coronary interventions from January 1998 to June 2010 at an academic medical center. Multivariable logistic regression models were used to estimate the association between off-hour admission and clinical outcomes adjusted for demographic and clinical variables.

There were 3,422 and 2,664 patients with AMI admitted during off-hours and regular hours, respectively. Patients admitted during off-hours were more likely to have STEMI (56% vs 48%, P < .001), have cardiogenic shock at presentation (6% vs 4%, P = .002), and develop shock after presentation (6% vs 5%, P = .004). After multivariable analyses, off-hour admission was not significantly associated with in-hospital mortality (odds ratio [OR] 1.12, 95% CI 0.84-1.49), 30-day mortality (OR 1.12, 0.87-1.45), or 30-day readmissions (OR 1.01, 0.84-1.20) but was significantly associated with composite major complications and any of emergent coronary artery bypass graft surgery, ventricular arrhythmia, stroke/transient ischemic attack, and gastrointestinal/retroperitoneal/intracranial bleeding (OR 1.27, 1.05-1.55, P = .015). There was no significant time trend in the adjusted mortality difference between off-hours and regular hours. The results were not different between STEMI and non-STEMI.

Patients who were admitted during off-hours did not have higher mortality or readmission rates as compared with ones admitted during regular hours at an academic medical center.