Abstract 16000: Impaired Fasting Glucose Increases Risk for an Unrecognized Myocardial Infarction: The Cardiovascular Health Study

Abstract

Background: Almost 25% of initial myocardial infarctions (MI) are unrecognized or clinically-silent (UMI). The prognostic implications of a UMI parallel those of symptomatic MIs. With diabetes mellitus (DM) being a known risk factor for UMI, further investigation is warranted regarding impaired fasting glucose (IFG) as a risk factor for UMI. Up to one-third of Americans have IFG . Therefore the relationship between UMI and IFG may have significant public health and clinical ramifications. Methods: The relationship between IFG and UMI was examined in the Cardiovascular Health Study: a cohort of individuals aged ≥ 65 years old. At year 2, there were 5,018 participants who had an initial 12-lead electrocardiogram (ECG). Of these participants, those with prior coronary heart disease (CHD), incident CHD, or a UMI on initial ECG were excluded. Our study population consisted of 1,714 participants without exclusions with measured fasting glucose (normal fasting glucose, NFG; n = 844), IFG (n=679), and DM (n=191) who underwent a baseline 12-lead electrocardiogram (ECG). Using Minnesota code, an UMI was identified by the presence of pathological Q waves or minor Q waves with ST-T abnormalities. Crude and adjusted hazard ratios (HRs) were calculated. Cox proportional hazard models were used to adjust for age, gender, body mass index, hypertension, anti-hypertensive medication use, total cholesterol, HDL cholesterol, lipid-lowering medication use, and cigarette use. Results: The sample was 36% male, 95% white, and had a mean age of 72.4 ± 5.6 years. Over a mean follow-up of 8.1 years, there were 94 UMIs identified among NFG subjects, 110 among IFG subjects, and 35 among DM subjects. Relative to NFG, the crude risk ratio estimates for UMI with IFG and DM were 1.53 (95% CI: 1.16-2.01) and 1.85 (1.24-2.70), respectively. With adjustment, the HR for UMI in IFG compared with NFG was 1.37 (95% CI: 1.03-1.83; p=0.032), and the HR for UMI in DM compared with NFG was 1.59 (95% CI: 1.24-2.70; p=0.035). Conclusion: Impaired fasting glucose increased the risk for a subsequent unrecognized myocardial infarction. Considering the enormous number of individuals at risk, these findings suggest the need for more aggressive CVD prevention activities.