Among men without heart disease but who have significant cardiac risk factors, a poor performance on exercise treadmill testing is associated with a more-than-doubled risk for myocardial infarction or other coronary heart disease event, according to an article in the September 28th issue of Circulation.

Exercise treadmill testing is not generally recommended as routine screening for people with no history or symptoms of heart disease. The current study was the first to evaluate exercise testing among asymptomatic people relative to their predicted coronary heart disease risk using the Framingham risk score.

The Framingham Risk Score assigns point values to risk factors such as hypertension, total cholesterol, high-density lipoprotein cholesterol, age, diabetes and smoking history to predict the risk of an event such as angina, myocardial infarction, or coronary death over a 10-year period. A risk score of 9 percent or less is considered low risk, 10 percent to 19 percent is considered intermediate risk, and a score of more than 20 percent is classified as high risk.

“Our results suggest that exercise testing may be of benefit in asymptomatic men with intermediate to high risk,” said Gary J. Balady, MD, lead author of the study.

He and his colleagues associated with the Framingham Heart Study found that ST-segment depression or failure to reach target heart rate during exercise testing more than doubled the 10-year risk of coronary event in men with high Framingham risk scores compared with men who did not have these findings on the stress test. Increased exercise capacity predicted lower coronary heart disease risk in the high-risk men.

“Greater exercise tolerance as measured in metabolic equivalents (METS) had a lower 10 year event rate,” he said. Each MET increase, which is a multiple of the resting metabolic rate, was associated with a 13 percent decrease in risk of coronary event. The study did not provide evidence to support exercise testing for asymptomatic women because the event rate in women was too low to suggest any significant correlations between the exercise results and future events, he said.

All study participants were asymptomatic at baseline. The study included 1,431 male and 1,612 female Framingham Heart Study participants. Their average age at baseline was 45 years and the participants were followed for more than 18 years.

During follow-up, 224 men (15.7 percent) developed a coronary event such as angina, myocardial infarction, or a cardiac-related death.

Balady said that high-risk men who have ST-segment depression or fail to achieve target heart rate on the exercise treadmill test “should get maximum risk reduction. That means aggressive blood pressure and lipid control, and of course, we want everyone to stop smoking.” Also, among these patients it would be prudent to consider additional diagnostic tests to determine the extent of disease, which may include imaging stress tests or invasive procedures such as angiography to assess the condition of arteries and locate any blocked or narrowed vessels.

However, he said it is important to note that this study did not find that exercise testing provided additional prognostic information in those with 10-year-CHD risk less than 10 percent. The authors concluded that clinicians should consider the global cardiac risk, using the Framingham Risk Score, prior to ordering an exercise tolerance test in asymptomatic men without known heart disease.