Myocardial perfusion imaging findings and 2-year outcomes in clinically referred asymptomatic patients with type 2 diabetes

Introduction. Type 2 diabetes mellitus is associated with an increased risk of coronary artery disease, which frequently remains clinically silent. Myocardial perfusion imaging with single-photon emission computed tomography is widely used for the detection of myocardial ischemia and risk stratification, but its prognostic value in asymptomatic diabetic patients remains uncertain. The aim of this prospective study was to evaluate myocardial perfusion imaging findings and 2-year cardiac outcomes in clinically referred asymptomatic patients with type 2 diabetes. Methods. This prospective observational study included 198 consecutive outpatients referred for stressrest SPECT myocardial perfusion imaging because of intermediate clinical suspicion of coronary artery disease. The study population consisted of 98 patients with type 2 diabetes and 100 patients without diabetes. Among them, 73 participants were classified as asymptomatic based on structured clinical interviews (37 diabetic and 36 nondiabetic patients). Myocardial  perfusion abnormalities were defined as a summed stress score ≥4, while inducible ischemia was defined as a summed difference score ≥2. Participants were followed for approximately 24 months for the occurrence of cardiac events including cardiac death, nonfatal myocardial infarction, and coronary revascularization. Eventfree survival was analyzed using Kaplan–Meier methodology. Results. Abnormal myocardial perfusion (SSS ≥4) was detected in 18.9% of asymptomatic diabetic patients and 22.2% of asymptomatic nondiabetic patients (p = 0.727). Inducible ischemia (SDS ≥2) was present in 8.1% and 8.3% of participants, respectively (p = 0.98). During the twoyear followup period, three cardiac events occurred in the diabetic group (8.1%), including one cardiac death and two coronary revascularizations, while no events occurred in nondiabetic  participants (p = 0.240). Kaplan–Meier analysis demonstrated no statistically significant difference in eventfree survival between diabetic and nondiabetic groups (logrank p = 0.083). Conclusions. Myocardial perfusion abnormalities were relatively frequent in clinically referred asymptomatic patients with type 2 diabetes; however, shortterm cardiac event rates were low. These findings suggest limited prognostic value of routine myocardial perfusion imaging in unselected asymptomatic diabetic populations and support a selective approach to noninvasive testing.