Myocardial Infarction Survival Improves with Exercise

While engaging in exercise may be difficult for some patients with heart disease, findings from a new study show that physical activity may improve survival. The study, published by the European Journal of Preventive Cardiology, suggests that the chance of surviving a myocardial infarction increases along with the amount of physical activity a patient participates in.

"We know that exercise protects people against having a heart attack," said study author Eva Prescott, MD. "Animal studies suggest that myocardial infarctions are smaller and less likely to be fatal in animals that exercise. We wanted to see if exercise was linked with less serious myocardial infarctions in people."

Included in the study were 14,223 patients who never had a heart attack or stroke and who participated in the Copenhagen City Heart Study. Patient activity levels were designated as sedentary, light, moderate, or high. Of these patients, 1664 experienced a myocardial infarction, with 425 dying immediately.

The authors gathered information about physical activity levels for all patients and compared those who died immediately to those who survived. Patients who exercised were found to be significantly less likely to die from myocardial infarction than those who had low levels of physical activity, according to the study.

The authors discovered a dose-response relationship between exercise and survival. Patients who were classified as having light physical activity were 32% less likely to die from myocardial infarction compared with sedentary patients. Those with moderate or high physical activity levels were 47% less likely to die compared with sedentary patients, according to the study.

"Patients who were sedentary were more likely to die when they got a myocardial infarction and patients who did exercise were more likely to survive,” Dr Prescott said. “There was also a dose-response relationship, so that the odds of dying if people got a myocardial infarction declined with the level of exercise they did, reaching an almost 50% reduction for those who were the most physically active."

These findings provide additional evidence that even moderate exercise can provide significant cardiovascular benefits and could improve survival. Interestingly, the authors hypothesize that exercise may change the blood vessel composition of the heart.

"One possible explanation is that people who exercise may develop collateral blood vessels in the heart which ensure the heart continues to get enough blood after a blockage," Dr Prescott said. "Exercise may also increase levels of chemical substances that improve blood flow and reduce injury to the heart from a heart attack."

While additional studies are necessary to prove the relationship, starting an exercise regimen prior to or after the onset of a cardiovascular condition may improve health and survival, according to the study.

"This was an observational study so we cannot conclude that the associations are causal. The results need to be confirmed before we can make strong recommendations,” Dr Prescott concluded. “But I think it's safe to say that we already knew exercise was good for health and this might indicate that continuing to exercise even after developing atherosclerosis may reduce the seriousness of a heart attack if it does occur."