Is glycated haemoglobin a sensitive index to identify left ventricular dysfunction two months after acute myocardial infarction in normotensive subjects?

Background: Glycated haemoglobin concentration (HbA1c) is a marker of glucose metabolism. Glucose intolerance is associated with a high incidence of left ventricular (LV) dysfunction after acute myocardial infarction (AMI). This study was carried out in order to relate HbA1c to LV function two months following AMI in 171 normotensive patients who were not previously known to have had diabetes mellitus.

Methods: Oral glucose tolerance test (GTT) and HbA1c. Echo and Doppler-cardiography were used to measure the E/A (peak velocity of the early filling/atrial contraction waves) at rest and at peak isometric exercise (IME), deceleration time (DT) of E wave, LV ejection fraction (LVEF), LV mass index and diastolic LV function.

Results: GTT was diabetic in 20, impaired in 35 and normal in 116 subjects. HbA1c was >6.0% (cut off level for high risk subjects) in 76 patients (67%) with impaired relaxation (E/A<1) during IME and in 30 patients (27%) with restrictive LV filling (identified by E/A=1-2, DT<140 ms). The sensitivity and specificity of HbA1c to predict underlying impaired LV relaxation were 68% and 37%, respectively, and to predict restrictive LV filling were 27% and 98%, respectively. Whereas in univariate analysis, DT.3 was linearly related to HbA1c only (p=0.0002), multiple regression analysis showed that HbA1c was related to LVEF, DT and E/A but not to LVH, LVMI, smoking habit, age, gender and creatinine kinase level during admission for AMI.

Conclusion: At 2 months after admission for AMI, HbA1c is related to systolic and diastolic LV function but not to LVMI or LVH. HbA1c is a sensitive predictor of impaired relaxation but highly specific to rule out underlying non-restrictive LV filling.