Newly diagnosed glucose intolerance and prognosis after acute myocardial infarction: comparison of post-challenge versus fasting glucose concentrations

BACKGROUND Recent studies have demonstrated that newly diagnosed glucose intolerance is common among patients with acute myocardial infarction (AMI). The purpose of this study was to assess the long-term clinical cardiovascular outcomes in participants with AMI with abnormal fasting glucose compared with normal fasting glucose and an abnormal oral glucose tolerance test (OGTT) compared with a normal OGTT. METHODS A prospective study was performed in 275 consecutive patients with AMI, 85 of whom had pre-diagnosed diabetes mellitus (DM). Those without DM were divided into two groups based on the 75 g OGTT at the time of discharge. Abnormal glucose tolerance (AGT) was defined as 2 h glucose ≥140 mg/dl; 78 patients had normal glucose tolerance (NGT) and 112 had AGT. The same patients were also reclassified into the normal fasting glucose group (NFG; n=168) or the impaired fasting glucose group (IFG; n=22). The association between the glucometabolic status and long-term major adverse cardiovascular event rates was evaluated. RESULTS Kaplan-Meier survival curves showed that the AGT group had a worse prognosis than the NGT group and an equivalent prognosis to the DM group (p<0.0005). Cox proportional hazard model analysis showed that the HR of AGT to NGT for major adverse cardiovascular event rates was 2.65 (95% CI 1.37 to 5.15, p=0.004) while the HR of DM to NGT was 3.27 (1.68 to 6.38, p=0.0005). However, Cox HR of IFG to NFG for major adverse cardiovascular event rates was 1.83 (0.86 to 3.87), which was not significant. CONCLUSION In patients with AMI, an abnormal OGTT is a better risk factor for future adverse cardiovascular events than impaired fasting blood glucose.