Sugar-like gravel in the gearbox and the question whether diabetes is a coronary artery disease equivalent

Abstract

With the broader availability of Positron Emission Tomography (PET) myocardial flow measurements at rest and during vasodilator stress became reality in routine non-invasive cardiac imaging. Assessment of myocardial blood flow improved diagnosis and risk assessment in the evaluation of patients undergoing perfusion PET imaging for coronary artery disease evaluation. Large studies have reported on the incremental value of coronary vasodilator assessment over perfusion data, above and beyond the assessment of myocardial ischemia and scar. Even in patients with neither scar nor ischemia, myocardial blood flow measures provided incremental prognostic value. In patients with normal qualitative scan results, the cardiac death rate was 36 times higher in patients in the lowest tertile of myocardial flow reserve (MFR) compared to the highest tertile, 3.6% and 0.1%, respectively. Moreover, the same authors demonstrated that coronary vasodilator dysfunction is a powerful, independent predictor of cardiac mortality in both, diabetic and non-diabetic patients. Decades ago, the controversy started, whether diabetes should be considered as a CAD equivalent : Over a follow-up period of almost 8 years, Haffner et al evaluated four groups of patients: patients without diabetes and no prior myocardial infarction, patients with diabetes but no prior infarction, patients without diabetes but prior myocardial infarction, and patients with diabetes and prior myocardial infarction. The outcome data demonstrated that diabetic patients with prior myocardial infarction had the highest mortality, whereas nondiabetic subjects without prior myocardial infarction had the best prognosis. Diabetic patients without prior myocardial infarction and nondiabetic patients with prior infarction had similar outcomes. Irrespective of the fact, if one calls diabetes a CAD equivalent, the disease is linked to high cardio-vascular risk, morbidity and mortality. According to the most recent standards of care by the American Diabetes Association, it is recommended that patients with diabetes aged 40 to 75 years even without atherosclerotic cardiovascular disease use moderate-intensity statin therapy in addition to lifestyle modification. Even Aspirin therapy (75 to 162 mg/day) may be considered as a primary prevention strategy in diabetic patients who are at increased cardiovascular risk, after a comprehensive discussion with the patient on the benefits versus the comparable increased risk of bleeding. Thus, diabetic patients definitely are at increased cardiovascular risk and therefore need patient-tailored care and treatment. In this issue of the Journal, Assante et al evaluated the interrelation between myocardial blood flow and cardiac events in a matched patient population of diabetic (n = 451) and non-diabetic patients (n = 451) with suspected CAD and normal qualitative myocardial perfusion as assessed by Rubidium PET. The main findings were that MFR was lower in diabetic patients than in non-diabetic patients, before and after matching. In patients with lower MFR the outcome was worse. One of the question is, why—what are the most important factors leading to a lower MFR—and can they be modified? The authors mention diabetes, age and Reprint requests: Michael J. Zellweger, MD, Cardiology Department, University Hospital Basel, University of Basel, Petersgraben 4, 4031 Basel, Switzerland; [email protected] J Nucl Cardiol 2021;28:1234–5. 1071-3581/$34.00 Copyright 2021 American Society of Nuclear Cardiology.