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

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).

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.

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.

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.