The correlation between albumin-corrected anion gap and prognosis in patients with acute myocardial infarction

Abstract

Aims: Acute myocardial infarction (AMI) is a cardiovascular disease with high morbidity and mortality. We collected patients with AMI from the Medical Information Mart for Intensive Care IV (v2.0) database and explored the association between serum albumin-corrected anion gap (ACAG) level and mortality in patients with AMI.

Methods and results: Data of adult patients with AMI were collected. According to the 360 day prognosis, patients were divided into survival and non-survival groups. Based on the ACAG level, patients were then divided into normal and high ACAG groups. Cox hazard proportional models and restricted cubic splines (RCSs) were used to investigate the correlation between ACAG and mortality. Kaplan-Meier curves were created to compare the cumulative survival rates between the high and normal ACAG groups. The receiver operating characteristic (ROC) curve was used to analyse the predictive value of ACAG for the prognosis of patients with AMI. Sensitivity and subgroup analyses were conducted to revalidate the results. Finally, 1783 patients were included. Elevated ACAG (>20 mmol/L) was significantly associated with 30 and 360 day mortality (P < 0.001). Adjusted for multiple confounding factors, the Cox proportional hazard analysis showed that elevated ACAG (>20 mmol/L) was an independent risk factor of increased all-cause mortality in patients with AMI (hazard ratio 1.423, 95% confidence interval 1.206-1.678, P < 0.001). RCS analysis further showed that there was a non-linear trend relationship between ACAG and the risk of all-cause mortality at 30 and 360 days (χ² = 10.750, P = 0.013; χ² = 13.960, P = 0.003). Kaplan-Meier survival curves showed that the 30 and 360 day cumulative survival rates of patients with AMI were significantly lower (log-rank test, χ² = 98.880, P < 0.001; χ² = 105.440, P < 0.001) in the high ACAG group. ROC curve analysis showed that the area under the curve (AUC) of ACAG was 0.651, while the AUC of anion gap (AG) was 0.609, indicating that ACAG had a higher predictive value for 360 day mortality than AG. When combined with Sequential Organ Failure Assessment score, the predictive performance of ACAG for 360 day mortality was better, with an AUC of 0.699. Sensitivity and subgroup analyses were conducted suggesting the stability of our results.

Conclusions: Elevated serum ACAG (≥20 mmol/L) is an independent risk factor for short-term and long-term mortality in critically ill patients with AMI, and it may assist clinicians and nurses identifying high-risk patients.

Keywords: Acute myocardial infarction; Albumin‐corrected anion gap; MIMIC‐IV; Mortality; Prognosis.

Figure 1

The flowchart of patients screening. ACAG, albumin‐corrected anion gap; AMI, acute myocardial infarction; ICU, intensive care unit; MIMIC‐IV, Medical Information Mart for Intensive Care IV.

Figure 2

(A) Selection process of prognostic variables of acute myocardial infarction by least absolute shrinkage and selection operator regression. (B) Selection process of the value of lambda by cross‐validation.

Figure 3

Restricted cubic spline analysis of the relationship between albumin‐corrected anion gap (ACAG) and the risk of (A) 30 and (B) 360 day all‐cause mortality in patients with acute myocardial infarction. CI, confidence interval; HR, hazard ratio.

Figure 4

Kaplan–Meier survival curve of (A) 30 and (B) 360 day cumulative survival rate for the normal and high albumin‐corrected anion gap (ACAG) groups.

Figure 5

The subgroup analysis between albumin‐corrected anion gap and 360 day all‐cause mortality. CI, confidence interval; HR, hazard ratio; IABP, intra‐aortic balloon counterpulsation.