Value of Myocardial Perfusion Imaging in the Detection of Ischemia Among Diabetic Patients with Diabetic Retinopathy

Abstract

SUMMARY T he relationship between cardiovascular events and retinopathy in diabetics were investigated among our many studies world wide yet, only few researches were conducted locally. Abnormal myocardial perfusion imaging (MPI) led to a more than five-fold increase in cardiovascular events. This emphasizes the value of SPECT MPI in predicting and risk-stratifying cardiovascular events in diabetic patients. Also, retinopathy in asymptomatic type 2 diabetics patients were significantly associated with perfusion abnormality and marked perfusion defects. Screening of these patients would be beneficial in the identification of sub-clinical coronary artery diseases in this patient population and this would decrease the overall mortality of silent myocardial ischemia. The sensitivity of MPI for detecting angiographic CAD was consistently above 70% in all studies published. Typical sensitivity values were in the region of 85–95% for both thallium-201(Tl-201) and technetium-99m sestamibi specially when ECG gated. As for diabetic retinopathy (DR), it is the most common and serious ocular complication of diabetes mellitus. About a third of all diabetics have signs of DR, and another third of those might have vision-threatening retinopathy, defined as severe retinopathy or macular edema. Apart from its effects on vision, the presence of DR also signifies a heightened risk of life-threatening systemic vascular complications. Our main aim was to express the value of myocardial perfusion imaging in detecting silent myocardial ischemia among diabetic patients with diabetic retinopathy. A case controlled study was conducted on forty patients selected from the endocrinology clinic and ophthalmology clinics at Ain Shams University hospital, to get diabetic patients with no established CAD or history of chest pain. Patients were also recruited from the nuclear cardiology department at Ain shams university hospital if they were referred for preoperative assessment or evaluation of silent ischemia after being assessed and reviewed by a senior staff member. Those patients were grouped into two groups according to whether they had DR or not in addition to other risk factors (Age, Gender, duration of diabetes, type of diabetes medical treatment, commitment to medications, annual ophthalmological check, dyslipidemia, hypertension, smoking, alcohol consumption, physical exercise and regular aspirin).All patients’ data and investigations including ECG and echocardiography reports were checked to ensure the lack of previous myocardial infarctions in addition to obtaining the appropriate consent from the patient. At the beginning, all patients were exercised on the treadmill or pharmacologically to achieve at least 85% of the maximum heart rate predicted for their age. Then, the radiotracer gets injected. Two days’ protocol was