Usefulness of biomarkers for predicting long-term mortality in patients with diabetes mellitus and non-ST-elevation acute coronary syndromes (a GUSTO IV substudy)

Abstract

The present study evaluated whether biomarkers of ischemia, inflammation, myocardial damage, and dysfunction are equally useful in patients who have diabetes mellitus (DM) for prediction of cardiac events in non-ST-elevation acute coronary syndrome (ACS). DM was present in 1,677 of 7,800 patients (21.5%) who had non-ST-elevation ACS and were included in the Fourth Global Utilization of Strategies To Open Occluded Arteries (GUSTO IV) trial. Creatinine, N-terminal pro-B-type natriuretic peptide (NT-pro-BNP), troponin T, C-reactive protein, and interleukin-6 were analyzed in serum samples that were obtained at a median of 9.5 hours from symptom onset. One-year mortality rates were 13.5% among patients who had DM (n = 227) and 6.9% among those who did not (n = 418, p < 0.001). The median level of NT-pro-BNP was 2 times as high in patients who had DM, whereas troponin T levels did not differ by DM status. Mortality increased with ascending quartiles of NT-pro-BNP, with 1-year mortality rates of 3.9% (n = 11) in the bottom quartile and 29% (n = 103) in the top quartile. In multivariable analyses, factors that were predictive of 1-year mortality in patients who did not have DM were also significant for those who did. Presence of ST depression > 0.5 mm had the highest odds ratio of 2.3 (95% confidence interval 1.2 to 4.6). NT-pro-BNP levels > 669 ng/L (odds ratio 2.0, 95% confidence interval 1.1 to 3.6) and interleukin-6 levels > 10 ng/L (odds ratio 1.9, 95% confidence interval 1.2 to 3.0) were significant biomarker predictors. In conclusion, DM confers a high long-term mortality in non-ST-elevation ACS. Despite a larger proportion of ST depression and increased levels of NT-pro-BNP and interleukin-6 at admission, these factors provide independent prognostic information that may improve risk stratification and guidance of treatment.