Heart Rate Test Predicts Death
Slow Heart Rate Recovery After Exercise Signals Death Risk
Sept. 2, 2003 -- People whose hearts don't slow down soon after exercise are at high risk of death.
That's the news from a six-year study of nearly 3,000 patients about 60 years old. The patients were referred to The Cleveland Clinic in Ohio for their first exercise treadmill test, and some also had a heart ultrasound. About half had previous heart disease, and about one-fourth once had a heart attack.
Six years later, more than 300 of the patients had died. Those whose heart rates did not slow down by at least 12 beats per minute within the first minute of exercise were two-and-a-half times more likely to have died. The cutoff was at least 18 beats per minute for those who had both the treadmill test and the heart ultrasound.
These findings held true whether or not the person had blocked heart arteries.
Slow heart-rate recovery didn't predict heart disease. But it added to the ability of other heart studies to tell whether patients were at high risk of death.
The Good News
The good thing about the heart-rate recovery test is that it can save healthy patients a lot of trouble. It might even help them avoid getting medicines they don't need, says study leader Michael S. Lauer, MD.
"I think that is extremely important, because we see a lot of patients who are being inappropriately labeled as being at uncertain risk and who are going through unnecessary tests, unnecessary procedures, or being put on medications that they probably don't need to take," Lauer says in a news release.
Don't Try This at Home
No, you can't just go for a run and take your pulse to find out your risk. Lauer says the heart-rate recovery test is much more sophisticated than that.
"The problems with people taking their own heart rates are, one, we use a standard protocol ... very different from what people do in the gym," he says. "Two, we measure heart rates very accurately using an electrocardiogram machine. Hence, we can't simply extrapolate our findings to casual heart-rate measurements in people doing typical exercise."
What Should You Ask Your Doctor?
Lauer and colleagues report their findings in the Sept. 3 issue of the Journal of the American College of Cardiology. An accompanying editorial by Bernard R. Chaitman, MD, of St. Louis University School of Medicine asks whether the heart-rate recovery test is ready for prime time.
Chaitman advises caution. He notes that it's not yet clear what different heart-rate recovery times mean for different patients. And he notes that it's not at all clear how doctors should treat patients with hearts that are too slow to calm.
Lauer agrees with this last point.
"The field is still in its infancy," he says. "We do not know whether this is a treatable risk factor."
Nevertheless, he suggests that the heart-rate recovery test would help doctors identify low-risk patients.