Impact of glycosylated hemoglobin (HBA1C) on the extent of perfusion abnormalities and left ventricular dysfunction using gated myocardial perfusion imaging and clinical outcomes in diabetic patients

OBJECTIVES: The aim of the study was to determine the impact of glycosylated hemoglobin (HBA1C) on the extent of perfusion abnormalities and left ventricular dysfunction (LVD) using gated myocardial perfusion imaging (GMPI) and clinical outcomes in diabetic patients. MATERIALS AND METHODS: A total of 1013 individuals (457 diabetic patients and 556 nondiabetic controls) were included in the study. Among the diabetic patients, 254 (56%) were male and 203 (44%) were female, with a mean age of 58±9 years. Stress GMPI was evaluated for the size and severity of perfusion defects, transient ischemic dilation (TID) ratio (>1.22), and LVD. Patients were followed up for 22 months (12-24 months) for fatal myocardial infarction or nonfatal myocardial infarction (NFMI). RESULTS: GMPI was found to be normal in 49 and 68% (P<0.0001) of diabetic patients and nondiabetic controls, respectively; fixed defects were seen in 21 and 16% (P=0.049), reversible defects in 30 and 16% (P<0.0001), and TID in 19 and 8% (P<0.0001) of participants in the diabetic and nondiabetic groups, respectively. Receiver-operating characteristic curve analysis revealed the diagnostic strength of HBA1C for coronary artery disease at a cutoff value greater than 7.3% (P<0.0001). Fasting blood sugar and duration of diabetes had poor diagnostic strength (P>0.05). The diabetic cohort was divided into group A (HBA1C>7.3%) and group B (HBA1C≤7.3%). GMPI in groups A and B revealed fixed defects in 33 and 9% and reversible defects in 41 and 22%, respectively; the sum stress score was 6±2 and 5±2, the sum thickness score was 38±8 and 32±6, and %left ventricular ejection fraction was 53±16 and 58±11, with TID in 32 and 8%, in groups A and B, respectively (all with P<0.0001). The Kaplan-Meier survival curves in groups A and B revealed event-free survival of 97.2 and 98.3% for fatal myocardial infarction (P=0.742) and 87.1 and 97.9% for NFMI (P<0.05), respectively. CONCLUSION: HBA1C is a reliable predictor of coronary artery disease and the magnitude of perfusion defects and LVD and the incidence of NFMIs are higher at an HBA1C level greater than 7.3%.