The association between glycemic variability and atrial fibrillation/in-hospital mortality in white and non-white patients with acute myocardial infarction: A retrospective cohort study

Glycemic variability (GV) may indicate underlying cardiovascular complications, but its association with atrial fibrillation (AF) in acute myocardial infarction (AMI) remains unclear. Therefore, this study aimed to assess the association between GV and the risk of AF in patients hospitalized with AMI. We analyzed 10,439 patients with AMI from the MIMIC-IV database (17 % STEMI, 61 % NSTEMI). The median age was 71 years (interquartile range: 61–80), and 27 % of patients underwent invasive treatment. GV was calculated based on post-admission plasma glucose levels (SD/mean glucose × 100 %). Outcomes included AF detection and in-hospital mortality, analyzed via multivariable logistic regression and restricted cubic spline (RCS) models. Among participants, 16.2 % developed AF, with incidence rising across GV quartiles (highest vs. lowest: 21 % vs. 7.1 %, p < 0.001). After adjustment, a higher GV was independently associated with AF (OR: 2.41, 95 % CI: 1.40–4.14, p = 0.002) and mortality (OR: 2.45, 95 % CI: 1.37–4.38, p = 0.002). Subgroup analyses confirmed consistent results, and RCS revealed nonlinear relationships (P-nonlinear<0.05). Notably, the predictive power of GV persisted in individuals without diabetes, as well as in the White (OR: 8.195, 95 % CI: 5.637−11.914, p < 0.001) and in non-White (OR: 2.697, 95 % CI: 1.587–4.586, p < 0.001) patients. Significant interactions were identified between GV and both ethnicity and heart failure status (all interaction p < 0.05). However, these results must be interpreted with caution due to potential bias. Elevated GV may be associated with the risk of AF and mortality in AMI patients, even without diabetes and in Whites. These findings should be validated in other cohort studies with larger numbers of non-White people and longer follow-up.