Heart Imaging: Worth the Risk?

Coronary computed tomographic angiography was no more effective than routine screening in reducing rates of heart attack and death in diabetes patients

(RxWiki News) Heart disease is one of the many health issues people with diabetes may face, so it's important to find it early. A new study found that one expensive test may not be better than the usual heart disease screening methods.

This new research found that patients with diabetes who underwent a test called coronary computed tomographic angiography (CCTA) did not have fewer heart attacks or lower death rates than patients who had the usual heart disease screening.

"A more important message is that routine screening for hypertension and hyperlipidemia is effective in diabetes patients who aren't showing symptoms and should be implemented more consistently," Dr. Gibbons said.

Coronary artery disease of the heart (CAD) is a major cause of illness and death in people with diabetes. CAD doesn't always have symptoms, so doctors usually screen patients by looking for high fats (hyperlipidemia) and sugar in their blood. They also check for high blood pressure. The results of those routine screening tests guide doctors to diagnose and treat CAD.

In CCTA, doctors inject dye into patients and take X-ray images of their hearts. The dye allows the doctors to see the structures of the heart blood vessels and check for CAD. This test is used in patients who have CAD and allows doctors to determine how serious a patient's CAD is.

Joseph B. Muhlestein, MD, of the Intermountain Medical Center Heart Institute in Murray, UT, led the study.

Dr. Muhlestein and colleagues noted that CCTA is expensive and exposes patients to radiation. Too much radiation can cause serious health effects and cancer, so limiting exposure when possible is advised, they said.

This study involved 900 patients with diabetes who did not have symptoms of CAD. Both patients with type 1 or type 2 diabetes were enrolled in the study. Patients with either type 1 or type 2 diabetes have high levels of sugar (glucose) in their blood. In type 1 diabetes, patients' bodies do not make enough insulin. Patients with type 2 diabetes make insulin, but their bodies do not use it effectively. Insulin is a hormone that regulates blood sugar.

About half of the patients in the study received the usual CAD screening for lipids, blood sugar and high blood pressure (hypertension). The other half of the patients were screened for CAD with CCTA. The research team followed the health of the patients for four years.

The researchers found that the rate of nonfatal heart attacks, angina that required hospitalization and death were about the same in both study groups. Angina is chest pain caused by poor blood flow through the blood vessels in the heart.

These events occurred in slightly more than 6 percent of the CCTA group and 7.6 percent of the patients who received the usual screening methods.

The study authors said that their findings did not support the use of CCTA screening in diabetes patients. Raymond J. Gibbons, MD, of the Division of Cardiovascular Medicine at the Mayo Clinic in Rochester, MN, said in an editorial about the study that he agreed.

When cardiovascular symptoms develop, CCTA may be a useful tool to get more information on the presence and extent of coronary artery disease in patients without diabetes.

The study and editorial were published online Nov. 17 in JAMA.

The Intermountain Research and Medical Foundation, Intermountain Healthcare Urban Central Region and the Intermountain Heart Institute funded the study. The authors disclosed no conflicts of interest.

Review Date: 
November 16, 2014