Impaired glucose tolerance in ischemic heart disease

Abstract

Background: Diabetes mellitus (DM) and impaired glucose tolerance test (IGT) are well known risk factors for cardiovascular disease (CVD). Individuals with IGT, a prediabetic state, are asymptomatic during many years and they often remain undiagnosed until they have developed overt diabetes or cardiovascular complications.

Patients and methods: A total 123 patients, aged 31-80 years with a previous acute myocardial infarction (MI) but without a known DM were examined. A standard oral glucose test (OGTT) was performed. Calculated intimamedia (clMa) of the brachial and common carotid arteries, flow-mediated dilation (FMD) of the brachial artery, left ventricular dimensions and systolic function were examined. Left ventricular diastolic function was evaluated by tissue velocity echocardiography. Microalbuminuria (MA) was defined as excretion of 20-200 mug albumin/min.

Results: The prevalence of DM and IGT in patients discharged from the CCU after MI without known DM diagnosis was high (38%). A fasting plasma glucose (PG) alone failed to identify more than 80% of the patients with abnormal glucose metabolism in this study. A multiple stepwise regression analysis revealed an independent and significant association between 2h PG and CRP (P <0.05). In the whole group calculated intimamedia area was associated with 2h PG after the glucose load (P <0.05). Both cIMa of the common carotid artery and the cIMa of the brachial artery were independently and significantly associated with left ventricular septum thickness. Microalbuminuria (MA) was present in 11% of patients. Patients with MA had significantly higher levels of 2h PG, lower displacement of the atrioventricular (AV) plane by M-mode echocardiography, thicker LV septum wall and a higher prevalence of impaired glucose tolerance compared with those with normoalbuminuria (p<0.05). Urinary albumin excretion (UAE) was significantly and positively associated with cIMa in both brachial and common carotid arteries, age and interventricular septum thickness. 2-h PG was significantly and negatively associated with diastolic TDI parameters such as early diastolic filling velocity (E-v), ratio of the early to late diastolic filling velocity (E'/A') and positively associated with Tei index (p<0.05). Left ventricular ejection time and Teiindex were significantly higher, E'/A' and E-v were significantly lower in patients with disturbed glucose metabolism compared with patients with normal glucose tolerance (p<0.01). These differences also remained significant when patients with DM were excluded from analysis.

Conclusions: The prevalence of abnormal glucose tolerance was high in patients discharged after MI without known DM. Glucose intolerance was associated with inflammation, surrogate variables for atherosclerosis, microalbuminuria and LV diastolic dysfunction. In this population FMD was probably not a reliable marker, since FMD is a functional parameter of the arterial system, particularly well suited for the study of the earlier stages of atherosclerosis in children and young adults without stiff arteries.