Type 2 Diabetes: Silent Heart Problems
Study: 1 In 5 People With Type 2 Diabetes at High Risk for Heart Disease Despite Lack of Symptoms
Aug. 6, 2004 -- It's known as silent ischemia: No chest pain; in fact there are no symptoms at all before a heart attack. For people with type 2 diabetes, this is a common condition -- one that doctors should test for, new research shows.
Heart disease is the leading cause of death among people with diabetes. Yet, unlike other people, these patients have few symptoms until the advanced stages -- until their first heart attack, writes researcher Frans J. Wackers, MD, a professor of cardiovascular medicine with Yale University School of Medicine in New Haven, Conn.
Wackers' paper appears in the current issue of Diabetes Care.
People with diabetes who are at high risk for heart disease -- men who are smokers or have high blood pressure for example -- should get a treadmill stress test for heart disease, he says.
According to the American Diabetes Association (ADA) guidelines, doctors should perform stress tests to check for coronary artery disease in people with diabetes who have two or more risks factors.
Doctors have had difficulty detecting early-stage heart disease in diabetes patients because there is nerve damage throughout the body. Therefore, chest pain -- which is the heart's signal that it's not getting sufficient blood and oxygen -- is dampened considerably.
This is the first study to examine how common asymptomatic heart disease is in people with type 2 diabetes and how effective the screening guideline set by the ADA is.
Wacker's study involved more than 1,000 volunteers in 14 centers throughout the U.S. and Canada -- all about 60 years old, with type 2 diabetes, and with no known or suspected heart disease.
Some had a stress test (like a treadmill test) to determine how well the heart can handle exercise. In this case, the test determines whether people with type 2 diabetes experienced signs of heart problems because of a lack of oxygen being delivered to the muscles. The test shows if blood supply is reduced, which should cause chest pain.
The others did not get the stress test, but were followed for the study period.
The results showed that 113 patients had abnormal testing:
- 22% -- 1 in 5 people with diabetes tested had signs of ischemia -- or lack of oxygen flow to the heart muscles -- on stress testing.
- 16% had specific areas of abnormal blood flow to the heart muscle, indicating coronary artery disease or clogged heart arteries.
- 40% had moderate to serious deficiencies of oxygen to the main pumping chamber of the heart, while 60% had small defects seen in the main chamber.
- Men were nearly three times more likely to have large and moderate irregularities.
- 306 patients had two or more risk factors for heart disease; 204 patients had less than two risk factors; however, all had the same frequency of left ventricle irregularities -- 22%. Abnormal deliver of oxygen to the heart occurred with equal frequency among patients with two or more risks or fewer than two.
These numbers justify screening by noninvasive testing such as stress tests, writes Wackers.
Also, his study shows that just one risk factor -- such as high blood pressure or being a smoker -- can greatly increase heart disease risk, he explains.
SOURCE: Wackers, F. Diabetes Care, August 2004: vol 27: pp 1954-1961.