Screening for coronary artery disease in asymptomatic patients with diabetes mellitus

Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 62-year-old man is evaluated during a routine visit. He is asymptomatic and walks 1 mile most days of the week. Medical history is significant for aortic stenosis, type 2 diabetes mellitus, hypertension, and hyperlipidemia. Medications are aspirin, metformin, lisinopril, metoprolol, and rosuvastatin.

On physical examination, the patient is afebrile, blood pressure is 130/66 mm Hg, pulse rate is 68/min, and respiration rate is 14/min. BMI is 29. Cardiac examination reveals a grade 2/6 early-peaking systolic murmur at the cardiac base. Carotid upstrokes are normal. The remainder of the examination is unremarkable.

Laboratory studies demonstrate a total serum cholesterol level of 150 mg/dL (3.89 mmol/L). Electrocardiogram is within normal limits. Echocardiogram from 1 year ago shows a peak velocity of 2.0 m/s, mean transaortic gradient of 13 mm Hg, aortic valve area of 1.5 cm2, and preserved ejection fraction.

Which of the following is the most appropriate management?

A. Echocardiogram
B. Exercise perfusion study
C. Exercise stress test
D. No additional testing

MKSAP Answer and Critique

The correct answer is D. No additional testing.

This patient should continue his current therapy; no additional testing is indicated at this time. The leading cause of death in patients with diabetes mellitus is cardiovascular disease, but routine testing for coronary artery disease (CAD) in asymptomatic patients with diabetes does not reduce mortality. Aggressive treatment of cardiovascular risk factors, however, does improve outcomes and reduce mortality as seen in the Steno-2 study. In this study, intensive intervention with behavior modification and multiple pharmacologic interventions aimed at achieving HbA1c levels below 6.5%, blood pressure below 130/80 mm Hg, and serum total cholesterol levels below 175 mg/dL (4.53 mmol/L) resulted in a 53% reduction of cardiovascular disease in a nearly 8-year follow-up. Continued risk factor management in this patient is, therefore, the most appropriate choice.

This patient does not need an echocardiogram. He is asymptomatic, and the murmur described is consistent with mild aortic stenosis as supported by his echocardiogram 1 year ago. He should undergo an annual clinical evaluation and echocardiography every 3 to 5 years. Echocardiography at this time in the absence of a clinical change is unnecessary.

If a screening test were to be performed prior to exercise, an exercise stress test would be the most appropriate test; exercise perfusion imaging provides no additional information. In routine screening of patients with diabetes in the DIAD study, despite 22% of patients having evidence of perfusion defects on single-photon emission CT, most of which were small, mortality rates were not changed compared with patients who did not undergo screening. The event rates were low in both groups, at about 3% over nearly 5 years.

The 2012 U.S. Preventive Services Task Force statement on screening for CAD with electrocardiography (ECG) recommended against screening with resting or exercise ECG for the prediction of CAD events in asymptomatic adults at low risk for CAD events, and stated that the evidence is insufficient to assess the balance of benefits and harms of screening in asymptomatic adults at intermediate or high risk for CAD events. The 2002 American College of Cardiology/American Heart Association (ACC/AHA) guidelines also concluded that there is no evidence to support routine testing in asymptomatic adults but concluded that it is reasonable to screen for CAD in asymptomatic patients with diabetes who plan to begin a vigorous exercise program.

Key Point

Routine screening for coronary artery disease in asymptomatic patients with diabetes mellitus does not reduce mortality.

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