Heart Screening for Diabetes Patients?

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Study Shows Screening Doesn't Reduce Heart Attacks Among People With Diabetes

By Salynn Boyles
WebMD Health News

Reviewed By Elizabeth Klodas, MD, FACC

April 14, 2009 -- Heart disease is a major killer of type 2 diabetes patients, with fatal heart attacks and strokes often occurring with few warning signs.

Routine screening for coronary artery disease has been suggested as a way to identify diabetes patients who are most at risk, but a new study shows no evidence to support the practice.

Screening did not result in a significant reduction in heart attacks or death from cardiac causes among patients with no symptoms of heart or artery disease followed for an average of five years.

Study researcher and professor of cardiovascular medicine Lawrence H. Young, MD, of Yale University School of Medicine, tells WebMD that the incidence of cardiovascular events among the study participants was surprisingly low.

The study appears in the April 15 issue of The Journal of the American Medical Association.

"There are about 20 million people living with type 2 diabetes in the United States," Young says. "While patients with [cardiovascular] symptoms certainly should be screened, as an overall public health measure, generalized screening doesn't appear to be appropriate."

Diabetes and Heart Disease

Two out of three people with diabetes die from heart disease or stroke, and diabetes patients have twice the incidence of heart disease as the general population.

According to the American Diabetes Association (ADA), adults with diabetes have a similar risk for having a fatal or life-threatening cardiovascular event as patients who have had a heart attack.

While these statistics are ominous, one unexpected finding from the new study is that efforts to lower cardiovascular risk appear to be working.

The investigation included 1,123 patients with type 2 diabetes who had no symptoms of coronary artery disease at enrollment.

Half the patients were screened with a test known as myocardial perfusion imaging (MPI), a type of stress test which also measures blood flow to the heart. The rest of the patients received standard medical management.

Coincidentally, the ADA, along with other medical organizations, revised their diabetes treatment guidelines soon after the study was started, calling for more aggressive treatment of cardiovascular risk factors such as high blood pressure and high cholesterol.

As a result, the percentage of study participants on preventive medications rose from 30% to 40% at the beginning of the trial to 70% to 80% by the end, study researcher Frans Wackers, MD, PhD, of Yale tells WebMD.

"It is very likely that this increase in preventive treatment had something to do with the unexpectedly good outcomes we saw," he says.

Specifically:

• Just seven nonfatal heart attacks and eight cardiac deaths occurred among patients who were screened (2.7%), compared to 10 nonfatal heart attacks and seven cardiac deaths among patients who were not screened (3%).
• Based on MPI testing, fewer than one in four screened patients (23%) showed evidence of cardiovascular disease, and just 6% had evidence of advanced coronary artery blockages.
• Just over 5% of screened patients had surgery to restore blood flow to the heart over the course of the five-year study, compared to 7.8% of patients in the unscreened group.

Better Treatments, Earlier Diagnosis

Patients with very abnormal MPI results had worse prognosis than other patients, but their risk of having a heart attack or dying from cardiac causes was still just 2.4% a year over the course of the study, Young says.

"People with type 2 diabetes certainly have an increased risk for coronary artery disease, but the doom-and-gloom message of recent years may have been overstated," Young says. "Patients receiving contemporary [preventive] treatment who are closely followed seem to do pretty well."

Diabetes specialist David Nathan, MD, of Harvard Medical School points out that patients with diabetes are being diagnosed earlier and this may also be a factor in better outcomes.

"Earlier detection means we are identifying more patients before they develop heart disease," he tells WebMD. "That means that fewer people are getting to the point where they need angioplasty or bypass surgery."

SOURCES: Young, L.H. The Journal of the American Medical Association, April 15, 2009; vol 301: pp 1547-1556. Lawrence H. Young, MD, professor of cardiovascular medicine, Yale University School of Medicine, New Haven, Conn. Frans Wackers, MD, PhD, Yale University School of Medicine, New Haven, Conn. David M. Nathan, MD, Diabetes Center, Massachusetts General Hospital, Harvard Medical School, Boston. American Diabetes Association web site: "Statistics for Heart Disease and Diabetes."

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