Screening asymptomatic patients with type 2 diabetes is recommended: Pro

Abstract

Cardiovascular morbidity is common in type 2 diabetes mellitus (DM) and several epidemiological studies reported that DM is associated with a marked increase in the risk of coronary artery disease (CAD). In 1999, the Finnish diabetologist, Yki-Jarvinen, provocatively stated: ‘‘diabetes is a cardiovascular disease which you diagnose by measuring the blood glucose.’’ In the same year, also the American Heart Association stated that it might be appropriate to say ‘‘diabetes is a cardiovascular disease.’’ At this time, DM is commonly considered as a CAD risk equivalent in many position papers and guidelines. However, screening asymptomatic DM subjects for detection of CAD and subsequent management remains controversial. It is well known that patients with DM and inducible myocardial ischemia are often asymptomatic and when CAD becomes clinically manifest it is frequently in an advance stage. Also episodes of transitory myocardial ischemia may be ‘‘silent’’ and abnormal asymptomatic ST changes may be recorded during ambulatory ECG monitoring. The exact prevalence of silent ischemia in DM remains unidentified. A review of studies assessing the presence of stress-induced ischemia by myocardial perfusion single-photon emission computed tomography (MPS) in asymptomatic diabetic patients with unrecognized CAD reported a prevalence ranging from 4% to 62%, largely due to the different patients characteristics. The annual event rate ranged from 2.4% to 5.8% in subjects with abnormal MPS and from 0.4% to 2.1% in those with normal MPS. At this time, largely based on the results of the Detection of Ischemia in Asymptomatic Diabetics (DIAD) study, the American Diabetes Association does not recommend screening for CAD in asymptomatic patients because it does not improve outcomes as long as cardiovascular risk factors are treated (level of evidence A). However, according to the European Society of Cardiology guidelines on diabetes, pre-diabetes, and cardiovascular diseases developed in collaboration with the European Association for the Study of Diabetes, this issue is still under debate and the characteristics of the patients who should be screened for CAD need to be better defined. In addition, the detection of occult CAD might allow the initiation of appropriate therapy at a time point when the disease process is more easily modifiable. Thus, testing of asymptomatic diabetic patients for risk stratification purposes is a paramount objective of cardiovascular imaging and this strategy is expected to lead to declines in cardiac morbidity and mortality. In this context, certain important questions are still to be addressed, such as the potential of coronary revascularization to reduce cardiac events in asymptomatic patients; the yield of non-invasive testing in identifying, reliably, a considerable proportion of those patients likely to benefit from this type of intervention in a cost-effective manner; and the questions of who, when and how to test. The Impact of in Ducible Ischemia by Stress MPS (IDIS) trial was designed to evaluate if in patients with DM the use of an aggregate score incorporating and weighting multiple risk factors could be superior to an approach based on the number of risk factors to define the patient’s risk. This multicentre study enrolled 822 consecutive patients with DM, and risk estimates for a CAD event were categorized as 0% to\3%, 3% to\5%, and C5% per year using Cox proportional hazards models. Model 1 used traditional CAD risk factors and ECG stress test data and model 2 used these variables plus MPS imaging data. CAD death, myocardial infarction, and unstable angina requiring coronary revascularization were the outcome measures. During follow-up (58 ± 11 months), 148 events occurred. Model 2 improved risk prediction compared to model 1 Reprint requests: Alberto Cuocolo, MD, Department of Advanced Biomedical Sciences, University Federico II, Via Pansini 5, 80131, Naples, Italy; cuocolo@unina.it J Nucl Cardiol 2015;22:1225–8. 1071-3581/$34.00 Copyright 2015 American Society of Nuclear Cardiology.