Why Cardiac Rehab Saves Lives

Sept. 26, 2011 -- Cardiac rehabilitation can be extremely effective, yet most people choose to avoid it. New research may make them think twice.

Cardiac rehabilitation can improve the ability of the heart to return quickly to a normal rate after exercise, and that in turn can double the chances of survival.

"Time and time again, cardiac rehabilitation has been shown to improve survival, to improve quality of life, and of course improve exercise capacity," says researcher Leslie Cho, MD, section head of preventive cardiology and rehabilitation at the Cleveland Clinic.

However, experts debate whether it's possible to reverse an abnormally slow return to a normal heart rate, and if doing so can lengthen life.

The new research sheds light on both points. "For the first time, we have shown that cardiac rehabilitation can train the heart to return to its normal rate quickly after exercise and improve survival. This is better than any medicine," Cho says.

The study is published in Circulation: Journal of the American Heart Association.

Cardiac Rehab and Survival

The researchers evaluated 1,070 patients who were referred for cardiac rehabilitation, three-quarters of them men. The average age was 61. They looked at the ability of the heart rate to return quickly to normal, also known as heart rate recovery. While 544 had an abnormal heart rate recovery at the start, the other 526 had a normal heart rate recovery.

They took part in a 12-week cardiac rehabilitation program. Typically, such a program includes doctor-supervised exercise sessions of about an hour or more, three times a week. It includes a warm-up and stretching and about 30 or more minutes of continuous aerobic activity followed by a cool-down.

Before and after the program, patients took exercise stress tests. Researchers measured how quickly their heart rate returned to normal afterward.

Heart rate recovery is also defined as the number of beats the heart rate declines during the first minute after stopping exercise.

"Abnormal is less than 12," Cho says. For instance: "If your peak was 100 beats per minute and it falls to 95 in the first minute after stopping, that's not good."

Experts have known that an abnormal heart rate recovery can predict an increased risk of death. Some small studies have found that heart rate recovery can be improved by exercise training.

However, it isn't known, the researchers write, if that improvement actually produces benefits such as longer survival.

Heart Rate Recovery

Among the 544 who started with an abnormal heart rate recovery, 41% had a normal one by the end of the program.

Of the 526 who started with a normal heart rate recovery, 89% maintained it. (The others, Cho says, may have had worsening heart disease, explaining the decline even with exercise.)