WEDNESDAY, Feb. 26, 2003 (HealthDayNews) -- A Cleveland Clinic study proposes what could be a revolutionary change in the way cardiologists look at exercise testing: It's what happens after the patient stops exercising that is really important.
Current treadmill testing focuses on "whether the ST segment [part of the electrocardiogram] is depressed during exercise," says Dr. Michael S. Lauer, lead author of a paper on the study in the Feb. 27 issue of The New England Journal of Medicine.
"In fact, that is the least important item. How much the heart rate comes down after exercise, whether there is ventricular ectopy, [abnormal heartbeats], is a far stronger indicator of risk than what happens to the ST segment," says Lauer, director of clinical testing in the department of cardiovascular medicine.
The study looked at almost 30,000 patients who underwent exercise testing at the Cleveland Clinic, either because they had coronary artery disease or were suspected of having it.
As is customary, the testers kept the heart monitor on for a few minutes after the person came off the treadmill. Centers now do that "just to be sure that the patient is not in trouble," Lauer notes.
However, in this trial the researchers looked closely at the results of heart monitoring, recording not only abnormal heartbeats but also how quickly the heart rate returned to normal. Then they looked at the number of cardiovascular deaths in the group, and how those deaths were related to what happened after exercise.
"The key message here is that the exercise test does not end when the patient stops exercising," Lauer says. "During the first few minutes after exercise, you can gather some extremely valuable data."
As expected, occurrence of abnormal heartbeats during exercise increased the risk of death over the next five years; the death rate for patients who had those abnormalities was 9 percent, compared to 5 percent for those who didn't.
However, the occurrence of abnormal heartbeats in the minutes after testing was an even stronger indicator of risk: 11 percent of the patients with those abnormalities died in the follow-up period.
"This is a very important finding in terms of being able to assess the risk of patients," says Dr. Richard A. Stein, a spokesman for the American Heart Association. He is more cautious about the implications of the study than Lauer, but does say "it could be revolutionary."
Cardiologists won't stop looking at what happens during exercise, Stein adds, but they will start paying more attention to the minutes after exercise.
"We would look at that and integrate the information into the various ways we assess risk," says Stein, who is a clinical medicine professor at Weill-Cornell Medical Center in New York City.
It remains to be seen how the finding will be integrated into medical practice, Stein says. Most probably, cardiologists will concentrate even more on controlling the known risk factors in patients whose after-exercise electrocardiograms are abnormal.
"It will refocus our attention in exercise testing," he adds.
More information
You can learn more about exercise testing from the American Heart Association. And for the value of exercise in your life, check out the National Institute on Aging.
