Out-of-hours presentation and 30-day myocardial infarction mortality in Mexico: a 2014-2023 retrospective study.

Introduction and objectives: Although acute myocardial infarction (AMI) remains a leading cause of death in Mexico, the impact of out-of-hours presentation on mortality remains understudied. The aim of this study was to evaluate the association between out-of-hours admissions (nights, weekends, holidays) and 30-day mortality in patients with AMI in Mexican hospitals, with a focus on the role of catheterization laboratories (cath lab). Methods: We conducted a retrospective cohort study to analyze emergency admissions from December 2014 through August 2023. Admissions were classified as out-of-hours or during-hours and were stratified by hospital type (with or without cath lab). Cox regression models adjusted for sociodemographic, health, and temporal variables were used to analyze mortality risks. Results: The study included a total of 29 131 cases: 4515 in percutaneous coronary intervention (PCI)-capable centers (group 1) and 24 616 in non-PCI-capable centers (group 2). Admissions outside regular hours accounted for 46.7% in group 1 and 53.6% in group 2. Adjusted analysis showed that although the presence of a cath lab was protective (HR, 0.25; 95%CI, 0.23-0.28), admissions outside regular hours increased the risk of mortality in both groups (group 1: HR, 1.25; 95%CI, 1.04-1.50; group 2: HR, 1.16; 95%CI, 1.11-1.22). Although overnight shifts increased the risk of death in both groups, weekends and holidays increased such risk only in non-PCI-capable centers. Conclusions: Out-of-hours admissions were associated with higher mortality, and unlike in developed countries, the presence of a cath lab did not improve out-of-hours outcomes.