Correlation between albumin-corrected calcium levels and prognosis in non-ST-elevation myocardial infarction patients: a retrospective cohort study using the MIMIC-IV database.

Background: Non-ST-segment elevation myocardial infarction (NSTEMI) significantly impacts global mortality. High-risk patients have a poor long-term prognosis. Hence, precisely assessing patient outcomes and early intervention is essential. However, its prognostic factors remain unclear. Therefore, it is necessary to elucidate these factors. This study aimed to investigate albumin-corrected calcium (ACC) as a prognostic marker in severe NSTEMI. Methods: A retrospective cohort study was conducted using data extracted from the MIMIC-IV database. Adult patients diagnosed with NSTEMI via ICD coding and admitted to the intensive care unit (ICU) for the first time were included. ACC was calculated from admission laboratory values using the formula: ACC = serum total calcium (mg/dL) +0.8 × [4.0 - serum albumin (g/dL)]. The primary outcome was 1-year all-cause mortality, and 90-day mortality was the secondary outcome. Cutoff values for ACC stratification were determined using restricted cubic splines. Least absolute shrinkage and selection operator (LASSO) regression was employed to select prognostic variables. The relationship between ACC and mortality was analyzed using Kaplan-Meier curves and multivariate Cox regression. Subgroup analyses were performed to assess the consistency of associations. Results: A total of 2,107 patients with NSTEMI were included. Based on an ACC cutoff of 9.19, patients were divided into low ACC (<9.19) and high ACC (≥9.19) groups. Baseline data showed significantly higher all-cause mortality at 1 year (P<0.001) and 90 days (P=0.02) in patients with high ACC compared with those with low ACC. Multivariate Cox regression analysis demonstrated that high ACC was independently associated with an increased risk of 1-year mortality [hazard ratio (HR): 1.22, 95% confidence interval (CI): 1.12-1.34, P<0.001] and 90-day mortality (HR: 1.20, 95% CI: 1.07-1.34, P=0.001). Kaplan-Meier survival curves demonstrated significantly lower survival rates in the high ACC group compared to the low ACC group at both 1 year (P<0.001) and 90 days (P=0.01). Conclusions: ACC is an independent predictor of mortality in patients with severe NSTEMI. These findings suggest that incorporating ACC into routine clinical evaluation may aid in the early identification of high-risk patients and guide closer monitoring and treatment strategies. However, further comprehensive prospective studies are needed to validate these findings.