|
||||||
|
|
|
|
|||||||||||
|
|||||||||||||
| ||||||||||||||||||||||||||||
Question: What is the role of cardiac testing in a diabetes patient who is asymptomatic for cardiovascular disease (CVD)?
Answer: Recognition that coronary artery disease (CAD) is the major cause of diabetes-related morbidity and mortality prompted the American Diabetes Association (ADA) in 1998 to review the data on CVD in diabetes and provide guidance to the practice community.1
For patients without known CVD, the ADA recommended a risk-factor–based approach whereby patients would undergo an initial exercise-stress electrocardiogram (ECG), with further imaging evaluation (myocardial perfusion imaging [MPI] or stress-echo testing) if the initial test was abnormal or uninterpretable.
For individuals with a normal stress ECG, the test would be repeated at intervals of 2–5 years, with more frequent testing for individuals with a greater risk-factor burden (hypertension, cholesterol, family history, smoking, proteinuria). The limitations of exercise-stress ECG testing were recognized; however, the substantially greater cost of MPI and stress-echo testing, along with the lack of long-term studies demonstrating their cost-effectiveness, discouraged ADA's including those tests as part of an initial screening strategy.
DIFFERENT MANAGEMENT TODAY?
In the intervening years, new data on the effectiveness of CAD interventions (both procedural and pharmacological) and new diagnostic modalities have become available. Based on the efficacy of aggressive drug interventions, particularly for lowering LDL cholesterol and blood pressure, guidelines for primary and secondary CVD prevention have emphasized early and persistent treatment to reach targets—usually without the need to document the presence of ischemia that some might have argued for 6–7 years ago.
The risk-factor–based approach for determining testing frequency has come under scrutiny as, unexpectedly, risk-factor burden has not proven strongly predictive of myocardial ischemia (as documented by MPI) in asymptomatic patients with type 2 diabetes.2 However, we continue to be faced with approximately 5–10% of CVD-asymptomatic diabetes patients who will have moderate to severe abnormalities on MPI scans,3 abnormalities that portend a substantially increased risk of a CVD event and mortality.
Results of the BARI-2 (Bypass Angioplasty Revascularization Investigation 2 Diabetes) trial should help clarify whether percutaneous and/or surgical interventions accompanying intensive medical therapy afford an advantage over medical therapy alone in diabetic patients with moderate CVD. For now, whether there is a cost-effective screening strategy that could identify these higher-risk individuals who might be candidates for intervention procedures remains an unresolved question.
Newer tests, such as EBCT (electron beam computed tomography), could identify patients with high coronary calcium scores who might be particularly suitable for perfusion imaging. Likewise, fast multislice computed tomography and magnetic resonance imaging might become helpful for identifying those at higher risk for moderate or severe ischemic lesions. Each of these methods may afford advantages over exercise ECG in having fewer uninterpretable studies (particularly in the obese). However, current data are insufficient to develop a clear diagnostic algorithm.
Given the emphasis on CVD in the diabetic patient in ongoing trials, we can
anticipate that better answers will be forthcoming. For now, after careful
history and exam, consideration of an initial screen using either exercise ECG
or myocardial calcium scores would be reasonable. Abnormal findings might
suggest further evaluation (e.g., MPI) of the extent of ischemia (as well as
assessment of ventricular function) to guide subsequent decisions about
intervention. 
Footnotes
|
Do you have a clinical question? Send it to docnews{at}diabetes.org.
References
2. Wackers FJ, Young LH, Inzucchi SE, et al.: Detection of silent
myocardial ischemia in asymptomatic diabetic subjects: The DIAD study.
Diabetes Care 27:1954–1961, 2004.
3. De Lorenzo A, Lima RS, Siqueira-Filho AG, et al.: Prevalence and prognostic value of perfusion defects detected by stress technetium-99m sestamibi myocardial perfusion single-photon emission computed tomography in asymptomatic patients with diabetes mellitus and no known coronary artery disease. Am J Cardiol 90:827–832, 2002.[Medline]
CiteULike 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
| ||||||||||||||||||||||||||||
|
||||||
|
| DOC News | Diabetes | Diabetes Care | Clinical Diabetes | Diabetes Spectrum |
