Exercise Stress Tests for Detecting Myocardial Ischemia in Asymptomatic Patients With Diabetes Mellitus
What is the relative finding of silent ischemia in diabetes (DM), as assessed by exercise myocardial perfusion imaging (MPI) and the electrocardiogram (ECG), in developing nations?
The prevalence of silent ischemia in DM was compared to a control group in developing nations using exercise MPI and ECG. The multinational study recruited participants at 12 sites in Asia, Africa, and Latin America. DM participants were age- and gender-matched 2:1 to non-DM individuals with ≥1 coronary artery disease risk factor. Exercise tests were interpreted in core labs in blinded fashion. The study included 392 DM and 205 control participants.
Among participants with diagnostic ECGs, a similar proportion of DM and controls had ischemic ECG (15% vs. 12%, p = 0.5). A significantly higher proportion of the DM group had MPI abnormalities compared with controls (26% vs. 14%, p < 0.001). In participants with ischemia on MPI, only 17% had ischemic ECG, whereas in those without ischemia on MPI, 10% had ischemic ECG. In a multivariable model, DM was independently associated with abnormal MPI (odds ratio, 2.1; 95% confidence interval, 1.3-3.5; p = 0.004). Women were less likely to have ischemia by MPI than men (10% vs. 30%, p < 0.001), and concordance between ECG and MPI was much worse in women.
In this prospective study, asymptomatic DM participants had more ischemia by exercise MPI than ECG, and had more ischemia by MPI but not ECG than the control group. Also, ischemia by MPI was less in women than men.
The authors stated that the trial was designed to compare prevalence of ischemia by exercise MPI to ECG, which is less expensive, more widely available, and the preferred modality according to current guidelines. Why they selected asymptomatic patients for the study, which are not considered in the referenced guidelines, rather than symptomatic patients with angina or coronary artery disease suspects, is not clear.
Keywords: Myocardial Perfusion Imaging, Coronary Artery Disease, Myocardial Ischemia, Latin America, Risk Factors, Electrocardiography, Developing Countries, Diabetes Mellitus, Exercise Test
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