MYOCARDIAL VIABILITY ON REST TC-99M SESTAMIBI SPECT IN PATIENTS WITH AND WITHOUT TYPE 2 DIABETES MELLITUS

Abstract

Background: Type 2 diabetes mellitus is associated with accelerated atherosclerosis, coronary microvascular dysfunction, and a high burden of clinically silent ischemia. These mechanisms may reduce myocardial perfusion and the amount of dysfunctional myocardium that remains viable. In settings where positron emission tomography and cardiac magnetic resonance are not routinely available, rest technetium-99m sestamibi single-photon emission computed tomography (Tc-99m Sestamibi SPECT) offers a practical approach to viability assessment.

Objective: To compare myocardial viability and rest perfusion characteristics between diabetic and non-diabetic patients referred for viability assessment.

Methods: A retrospective cross-sectional study included 109 patients who underwent rest Tc-99m Sestamibi SPECT at a tertiary-care nuclear medicine department in Peshawar, Pakistan, from January to May 2026. The cohort comprised 67 patients with type 2 diabetes and 42 without diabetes. Myocardial tracer uptake was evaluated using the standard 17-segment model. Clinical characteristics, left ventricular ejection fraction (LVEF), perfusion-defect severity, viable and non-viable segment counts, and final viability interpretation were compared descriptively; categorical associations were assessed using chi-square testing.

Results: Men comprised 73.4% of the sample. Predominantly viable myocardium was identified in 81.0% of non-diabetic patients and 50.7% of diabetic patients, whereas predominantly non-viable myocardium was present in 19.0% and 49.3%, respectively. Severe perfusion defects occurred only in the diabetic group (11.9%), and moderate defects were also more frequent in diabetic patients (44.8% vs 28.6%). The mean number of non-viable segments was higher in diabetic patients (2.38 ± 1.25 vs 1.60 ± 1.12), while viable segments were fewer (14.68 ± 2.10 vs 15.42 ± 1.87). Diabetes status was strongly associated with final viability interpretation (p<0.001) and perfusion-defect severity (p=0.005), but not with LVEF category (p=0.845).

Conclusion: Diabetes was associated with a substantially less favorable myocardial viability profile on rest Tc-99m Sestamibi SPECT. Rest-only SPECT may provide clinically useful viability information for risk stratification and revascularization planning, particularly where advanced multimodality imaging is limited.