Stress Echocardiography Spots Diabetic Patients' Increased Cardiac Risk

ROCHESTER, MINN. -- Abnormalities detected using ultrasound imaging after treadmill exercise testing can help doctors identify which patients with diabetes are at most risk for a heart attack or cardiac death, according to a Mayo Clinic study published in the May issue of the Journal of the American College of Cardiology.

The study evaluated 563 diabetic patients with known or suspected heart disease who had been given exercise echocardiograms. There were no cardiac events in the first two years among those with normal stress echocardiograms, but nearly one-third of those whose studies showed multivessel disease suffered a heart attack or cardiac death within five years.

Diabetes mellitus is one of the leading risk factors for heart disease, and heart disease is the number one cause of death for diabetic patients. Over 15 million Americans have type 2 diabetes, which is related to age and being overweight. With the aging population, and with obesity rates increasing by nearly 60 percent since 1991, the number of diabetes cases is expected to continue increasing.

"We need cost-effective methods to determine which of these patients need aggressive heart disease treatment," says Patricia Pellikka, M.D., a Mayo Clinic cardiologist and author of the study. "This study indicates that exercise echocardiography is useful for that purpose."

Patients with known or suspected heart disease are often given nuclear perfusion stress tests, in which a radioactive dye is injected through a vein. Images of the heart taken during exercise then show which regions are not getting adequate blood supply. Stress echocardiography, by contrast, is completely non-invasive and significantly less expensive. It uses sound wave imaging to evaluate the heart muscle before and after exercise to determine blood flow to various regions. The imaging technology is similar to what is used during pregnancy for ultrasound images of the developing fetus.

"Diabetic patients often do not experience the typical symptoms of chest pain that others with heart disease have," says Dr. Pellikka. "This study shows that stress echocardiography could be a very effective tool to screen them for heart attack risk. Patients with no abnormalities could wait two years and then repeat the test to see whether the disease has progressed. Those whose exercise echocardiograms show disease in more than one region of the heart should have an angiogram to determine whether bypass surgery or angioplasty is needed to restore adequate blood flow."

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