SHORTER WARRANTY PERIOD OF A NORMAL MPS IN DIABETICS WITH IMPAIRED GLYCEMIC CONTROL (HBA1C >7.3)

Abstract

Objective: To find out clinical outcomes in diabetics with normal stress myocardial perfusion scans (MPS) having glycosylated hemoglobin (HBA1C) > or ≤ 7.3.

Material and Method: This was a prospective study conducted at nuclear cardiology department of Karachi Institute of Heart Diseases (KIHD), Karachi, Pakistan. Total 251 diabetics who had a normal stress MPS were included. On the basis of their HBA1C these patients were categorized into Group A (HBA1C >7.3) and Group B (HBA1C ≤ 7.3). This cut-off was taken from our previously published study performed upon early cohort.These patients were followed for 05 years for fatal and non-fatal myocardial infarction (FMI and NFMI). Follow-up was not available in 29 patients, who were excluded from the study leaving a cohort of 222.

Results: Group A included 57 while Group B had 165 diabetics with a mean age of 59 vs. 57 years and male to female ratio of 42:58% vs. 40:60% respectively (non-significant). Mean body mass index (BMI) in Group A and B was 28.318 vs. 27.532 kg/m² (non-significant). Mean HBA1C and fasting blood glucose in Group A were significantly higher than Group B (8.363 vs. 6.630 and 135 mg% vs. 120 mg% respectively).  No significant difference was seen in prevalence of hypertension, dyslipidemia, family history of coronary artery disease (CAD) and smoking between two cohorts. Dipyridamole stress was used in 58% vs. 56% in Group A and B respectively (non-significant) while no significant difference was seen in effort tolerance (Metabolic Equivalent Task; METS) of participants of both groups.  In both groups stress MPS was normal with normal left ventricular function parameters (non-significant). During 05 years follow-up, no significant intergroup difference in FMI incidence was seen (02 vs. 01 FMIs in Group A and B respectively, p-value non-significant). However, significantly high NFMI was seen in Group A as compared to Group B [11 (19.301%) vs. 04 (0.2.420%), significant p value]. Important to note that this difference was significant only in last 03 years of follow-up.

Conclusion: We conclude that diabetics with impaired glycemic control (HBA1C >7.3) had higher non-fatal MIs after 02 years of a normal MPS than diabetics with better control.  Warranty period of a normal MPS in poorly controlled diabetics is shorter and frequent retesting in subsequent years is warranted.