Relation between anion gap and 28-day all-cause mortality in patients with chronic total coronary occlusion

Chronic total coronary occlusion (CTO) is a critical condition associated with poor outcomes in patients with coronary artery disease. Anion gap, a readily available laboratory marker, has been linked to various clinical outcomes, but its relationship with mortality in CTO patients is not well established. This study aimed to investigate the association between anion gap and 28-day all-cause mortality in patients with CTO admitted to the intensive care unit (ICU). We conducted a retrospective cohort study using data from the medical information mart for intensive care, version IV database (version 3.1), spanning from 2008 to 2019. Patients with CTO admitted to the ICU were included, and those with missing anion gap data or non-first-time ICU admissions were excluded. We used univariate and multivariate Cox regression models to evaluate the impact of anion gap on 28-day all-cause mortality. Adjustments were made for various clinical and laboratory parameters. A total of 830 patients were included in the analysis. The mean age was 69.4 years, and 76.5% were male. Anion gap was significantly associated with 28-day all-cause mortality in both univariate (hazard ratio [HR] 1.09, 95% confidence interval [CI] 1.05–1.13, P < .001) and multivariate analyses (HR 1.15, 95% CI 1.10–1.20, P < .001). The risk increased across quartiles, with the highest risk observed in the highest quartile (Q4, HR 21.22, 95% CI 2.78–161.93, P = .003). Subgroup analysis revealed significant interactions with gender and heart failure. Anion gap is a significant predictor of 28-day all-cause mortality in patients with CTO admitted to the ICU. Our findings suggest that monitoring anion gap could be clinically useful for risk stratification in this patient population. Further studies are needed to confirm these results and explore potential mechanisms.