High Baseline Fitness Level Tied to Improved Survival After MI

The better shape a person is in before an MI, the more likely they are to survive after it.

Those are the conclusions from a large analysis of participants who underwent exercise stress testing as part of a study investigating the impact of exercise capacity on cardiovascular outcomes and mortality. Overall, a higher baseline fitness level—assessed, on average, 6 years before the first MI—was independently associated with a lower risk of mortality 28, 90, and 365 days after the infarction. Each metabolic equivalent (MET)-increment achieved during testing was associated with an 8% to 10% lower risk of death across the 3 time points.

“This is about fitness before you ever have an MI,” said senior investigator Michael Blaha, MD, of Johns Hopkins Hospital (Baltimore, MD).

Published in the February 2016 issue of Mayo Clinic Proceedings, the study included 69,885 men and women (mean age 62 years) without a history of MI undergoing treadmill stress testing as part of the Henry Ford Exercise Testing (FIT) project. Within this group, the researchers studied 2061 participants who went on to have an MI. Among those who had an MI, 10.6%, 15.7%, and 24.5% had died by 28, 90, and 365 days.

Higher exercise capacity at baseline continued to be associated with lower mortality risk after multivariable adjustment, as did patient age and history of hypertension, antihypertensive medication use, and statin use.

To TCTMD, Blaha explained that studies have shown a higher level of fitness is associated with better overall survival and reduces the risk of MI. In the cardiac rehabilitation setting, achieving a high level of fitness after an MI is also associated with improved outcomes.

“We looked at a different question, which we think is very novel,” he said. “We looked at fitness at baseline and followed a large enough cohort to find enough patients who went on to have a heart attack. We looked at survival after their heart attack, correcting for age and all of their risk factors. What we found was that baseline fitness predicts their survival after their first heart attack.”

The study has implications for individuals with a family history of heart disease or those with advanced subclinical atherosclerosis, such as those with evidence of coronary calcification, said Blaha. “For those people who are definitely at higher risk of having a heart attack and ask, ‘Well, what can I do to improve my outcome?’ Fitness not only reduces the risk of having a heart attack, but if one were to have a heart attack, it makes it much less likely that the heart attack is fatal.”