Sign and symptom-level factors associated with in-hospital mortality in patients with ST-elevation and non-ST-elevation myocardial infarction

Early risk stratification in acute myocardial infarction (AMI) is essential for guiding clinical management. While established risk models incorporate composite clinical and laboratory data, the prognostic value of individual presenting symptoms remains incompletely defined, particularly across AMI subtypes. To evaluate bedside findings associated with in-hospital mortality in patients with acute myocardial infarction, with separate analyses for ST-elevation AMI (STEMI) and non-ST-elevation AMI (NSTEMI). This retrospective cohort study included 5,949 adult patients with AMI admitted to Afshar Hospital, Yazd, Iran, between November 2017 and December 2025. Presenting signs and symptoms were abstracted from admission records. Associations with in-hospital mortality were assessed separately for STEMI and NSTEMI using univariate comparisons and age- and sex-adjusted Cox proportional hazards models, with pre-specified reduced models and subgroup analyses, including formal interaction testing. Among 5,949 patients with AMI, 3,673 had complete symptom documentation and were included in symptom-based analyses (1,932 STEMI, 1,741 NSTEMI). Pulmonary crackles (age- and sex-adjusted HR 3.76, 95% CI 1.69–8.36, p = 0.001) and cold extremities (HR 10.31, 95% CI 2.10–50.60, p = 0.004) were associated with higher in-hospital mortality in STEMI. In NSTEMI, associations were unstable because of the low number of mortality events. A significant crackles-by-age interaction ( p = 0.016) indicated a stronger association of pulmonary crackles in STEMI patients aged ≤ 65 years (HR 11.22, 95% CI 4.32–29.12) than in those aged > 65 years. Symptom documentation was unavailable for 38.5% of patients, and missingness patterns suggested potential missing-not-at-random bias. Individual bedside symptoms, particularly signs of systemic congestion and hypoperfusion, were associated with in-hospital mortality in AMI and may provide complementary information for early bedside risk assessment.