Editorial point of viewScreening of asymptomatic patients with type 2 diabetes mellitus for silent coronary artery disease: Combined use of stress myocardial perfusion imaging and coronary calcium scoring
Section snippets
MPI in symptomatic patients with diabetes mellitus
Although the role of stress MPI for risk stratification is well established in the general population, similar data are relatively scarce in patients with diabetes mellitus. Several studies in the literature suggest a high prevalence of abnormal MPI studies in diabetic patients (Table 1).8, 9, 10, 11, 12, 13, 14 Zellweger et al8 noted that this high prevalence was dependent on the clinical presentation (ie, angina or shortness of breath). Patients with diabetes who presented with shortness of
MPI in asymptomatic patients with diabetes mellitus
Nesto et al15 reported in 1990 that 57% of asymptomatic patients with diabetes mellitus and peripheral vascular disease had evidence of silent CAD on stress MPI. A number of subsequent studies have confirmed the presence of silent ischemia in asymptomatic patients with diabetes.8, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 The reported prevalence of silent ischemia, however, varied markedly between studies, from 6% to 59%.8, 19, 23, 25, 27, 28, 29 This wide range in the prevalence
Prospective studies in asymptomatic patients with diabetes mellitus
Several prospective studies have been performed in truly asymptomatic patients with diabetes mellitus (section C, Table 2).19, 20, 25, 29, 30, 31 In general, these studies showed a lower prevalence of silent CAD, ranging from 6% to 22%. However, there were important differences in design and stress testing methodology. These methodologic differences may explain the variation in the observed prevalence of silent CAD. For example, in the Milan Study on Atherosclerosis and Diabetes (MiSAD),
Value of CAC scoring in patients with diabetes mellitus
CT techniques (EBCT, multislice CT) allow for noninvasive detection and quantification of CAC, an early marker of CAD.32 Various studies have recently demonstrated the prognostic significance of CAC scores in the general population.33, 34, 35, 36 Because of the previously mentioned ominous association between CAD and diabetes mellitus, the prevalence of CAC has been explored in patients with diabetes without known CAD.37 In a cohort study of 30,904 asymptomatic individuals, including 1,075
Relative values of CAC score and ischemia on MPI for detecting CAD
Currently, only limited data are available on the relative values of CAC and MPI for detecting silent CAD and prognostication. He et al42 prospectively examined 3,895 asymptomatic subjects with EBCT; 411 of these underwent stress MPI. Only 6.8% of these subjects had known diabetes mellitus. The likelihood of stress-induced myocardial ischemia on MPI increased in parallel with the CAC score, in particular at CAC scores of 400 or greater. Of patients with CAC scores of 400 or greater, 46% had
Conclusion
Stress-induced abnormalities on MPI and positive CAC scores represent two different aspects of CAD. The first one reflects the pathophysiologic consequences of luminal obstructive CAD, whereas the second indicates the presence of the atherosclerotic process with calcium deposition in the vessel wall. The recent findings of truly prospective studies in asymptomatic patients with diabetes mellitus suggest a relatively low prevalence of silent CAD as evidenced by abnormal MPI results. Although in
Acknowledgment
The authors have indicated they have no financial conflicts of interest.
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