Pre-diabetes mellitus newly diagnosed after myocardial infarction adversely affects prognosis in patients without known diabetes

Abstract

Background: Effect of pre-diabetes mellitus on post-myocardial infarction prognosis is unclear. Methods: Retrospective cohort analysis of 1056 myocardial infarction survivors with fasting plasma glucose and 2-h post-load plasma glucose measured. Major adverse cardiovascular events included death, non-fatal reinfarction and ischaemic stroke. Cox proportional hazard regression identified predictors of event-free survival. Continuous net reclassification improvement and integrated discrimination improvement determined the added predictive value of glycaemic indices. Results: Major adverse cardiovascular events occurred in 25.1% and 16.4% patients with and without pre-diabetes mellitus (hazard ratio with pre-diabetes mellitus: 1.56; 95% confidence interval: 1.17–2.08; p = 0.003) in the whole cohort and in 24.1% and 17.2% patients (hazard ratio with pre-diabetes mellitus, 1.43; 95% confidence interval: 1.03–1.98; p = 0.033) in the matched cohort, respectively. Pre-diabetes mellitus predicted major adverse cardiovascular events–free survival in whole (hazard ratio: 1.39; 95% confidence interval: 1.03–1.89; p = 0.033) and matched cohorts (hazard ratio: 1.42; 95% confidence interval: 1.01–1.99; p = 0.043). The 2-h post-load plasma glucose, but not fasting plasma glucose, predicted major adverse cardiovascular events–free survival in the whole (hazard ratio: 1.16; 95% confidence interval: 1.07–1.26; p < 0.0001) and matched cohorts (hazard ratio: 1.20; 95% confidence interval: 1.09–1.31; p < 0.0001). Adding 2-h post-load plasma glucose to models containing fasting plasma glucose, significantly improved net reclassification improvement and integrated discrimination improvement for both cohorts, but not vice versa. Conclusion: Pre-diabetes mellitus predicts major adverse cardiovascular events after myocardial infarction. The 2-h post-load plasma glucose predicts prognosis better than fasting plasma glucose in these patients.