November 18, 2014

Findings Do Not Support Routine CT Angiography in Patients With Diabetes

CHICAGO -- November 18, 2014 -- A study published in JAMA and presented at the 2014 Scientific Sessions of the American Heart Association (AHA) showed that coronary computed tomographic angiography (CCTA) should not be used as routine screening for coronary artery disease (CAD) among patients with diabetes.

Joseph B. Muhlestein, MD, Intermountain Medical Center Heart Institute, Murray, Utah, and colleagues examined whether screening patients with diabetes deemed to be at high cardiac risk CCTA would result in a significant long term reduction in death, myocardial infarction (MI) or hospitalisation for unstable angina.

For the study, 900 patients with types 1 or 2 diabetes of at least 3 to 5 years' duration and without symptoms of CAD were randomised to receive CAD screening with CCTA (n = 452) or to standard national guidelines-based optimal diabetic care (n = 448).

Patients were recruited from 45 clinics and practices of a single health system (Intermountain Healthcare, Utah). Standard or aggressive therapy (for treating abnormal lipid, blood pressure and glucose levels) was recommended based on CCTA findings.

At an average follow-up time of 4 years, the primary outcome event rates (composite of all-cause death, nonfatal MI, or unstable angina requiring hospitalisation) were not significantly different between the CCTA and the control groups (6.2% [28 events] vs 7.6% [34 events]).

The incidence of the composite secondary end point of ischemic major adverse cardiac events (CAD death, nonfatal MI, or unstable angina) also did not differ between groups (4.4% [20 events] vs 3.8% [17 events]).

“CCTA involves significant expense and radiation exposure, so that justification of routine screening requires demonstration of net benefit in an appropriately high-risk population,” the authors wrote. “These findings do not support CCTA screening in this population.”

In an accompanying editorial, Raymond J. Gibbons, MD, Mayo Clinic, Rochester, Minnesota, wrote: “Although studies like this are often characterised as ‘negative,’ there are several important messages. As suggested by the authors, future randomised trials of cardiac imaging in asymptomatic patients with diabetes should be larger and focused on an enriched study population at higher risk. Such a strategy would certainly enhance the chances of success. A more important and more currently applicable message is that guideline-directed medical therapy for hypertension and hyperlipidaemia is effective in asymptomatic patients with diabetes and should be implemented more consistently. The data in this study suggest that Intermountain Healthcare has set a new published standard for what is achievable in patients with diabetes with respect to blood pressure control and lipid-lowering therapy and that, when therapy is applied this effectively, patients with diabetes are no longer at high risk for major cardiovascular events.”

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