Higher levels of physical fitness may improve the chances of survival after a first attack, researchers at Johns Hopkins and the Henry Ford Health System report.
Their findings, based on medical records data gathered from more than 2,000 men and women, are described in the online Feb. 1 edition of Mayo Clinic Proceedings.
"We knew that fitter people generally live longer, but we now have evidence linking fitness to survival after a first heart attack," says Michael Blaha, director of clinical research for the Ciccarone Center for the Prevention of Heart Disease and assistant professor of medicine at the Johns Hopkins University School of Medicine. "It makes sense, but we believe this is the first time there is documentation of that association."
For the new study, Blaha and his colleagues focused on medical records of individuals who had taken a treadmill stress test before their first heart attack and used the patient's achieved metabolic equivalent score—MET, for short&mdash:as a quick, although not perfect, measure of energy consumption at rest and during physical activity. The higher the MET score, Blaha says, the more physically fit the participants were considered to be.
The researchers found that overall, the 634 people achieving MET scores of 10 or higher had about 40 percent fewer deaths after a first heart attack as compared to the rest of the patients. They also observed that one-third of the 754 patients with a MET score of 6 or less died within a year of their first heart attack. Overall, their results showed an 8 percent reduction in death risk for each whole-number increase in MET score after a first heart attack.
"Our data suggest that doctors working with patients who have cardiovascular risk factors should be saying, 'Mr. Jones, you need to start an exercise program now to improve your fitness and chances of survival, should you experience a heart attack,'" says Clinton Brawner, clinical exercise physiologist at Henry Ford Health System.
The investigators noted that their study design has limitations, including the fact that they could not assess whether improving fitness levels as measured by MET scores can decrease the risk of death from a heart attack. Also, Blaha says, they didn't determine if people who are fitter have less damaging heart attacks, or if they have same-sized heart attacks as those who are unfit but survive them better. Decades of research show that cardiovascular fitness does increase blood flow to the heart and may aid in healing, which is a likely contributing factor to lower mortality rates.