Published: May 16, 2013 | Updated: May 16, 2013
By Chris Kaiser , Cardiology Editor, MedPage Today
Action Points
- These studies were published as abstracts and presented at a conference. These data and conclusions should be considered preliminary until published in a peer-reviewed journal.
- A sustained improvement in fitness level reduces the risk of heart failure hospitalization over time.
- Point out that the study suggests that the risk of heart failure in your 60s and 70s is modifiable through sustained exercise beginning in midlife.
That middle-age bulge can damage the heart, but a sustained improvement in fitness level reduces the risk of heart failure hospitalization over time, researchers found.
Those persons who increased their fitness level over the course of 8 years, as well as those who stayed fit, had lower rates of heart failure hospitalization compared with those who had persistently low fitness levels (0.64% versus 0.88% per year), according to Ambarish Pandey, MD, of the University of Texas Southwestern Medical Center in Dallas, and colleagues.
Each metabolic equivalent (MET) increase in middle-age fitness was associated with a 17% reduced risk in future heart failure hospitalization (adjusted HR 0.83, 95% CI 0.71-0.92, per MET), Pandey reported at the American Heart Association’s Quality of Care and Outcomes Research (QCOR) Scientific Sessions 2013 in Baltimore.
“The risk of heart failure in your 60s and 70s is modifiable through sustained exercise beginning in midlife,” Pandey told MedPage Today.
“We have known for a few decades that a change in fitness is associated with a reduced risk of mortality. But no one had looked at the impact of improved fitness over time on the risk of heart failure,” he said.
He and his colleagues therefore ranked fitness levels of 9,050 men and women (average age 48, 15% women), with low fitness defined as the lowest quintile of fitness (Q1) and high fitness defined as quintiles 2 through 5.
Participants underwent two cardiorespiratory fitness measurements at about 8 years apart.
The primary endpoints were a change in METs as a continuous variable and a change in the category of fitness between the two cardiorespiratory tests.
Pandey and colleagues matched baseline data from the Cooper Center Longitudinal Study to Medicare administrative claims data for heart failure hospitalizations.
After 60,635 person-years of follow-up, they found a correlation between the change in midlife fitness and future heart failure hospitalization (according to quintiles, from baseline to follow-up):
- High level of fitness to high level of fitness — heart failure hospitalization rate about 0.30%
- Low to high — about 0.65%
- High to low — about 0.75%
- Low to low — 0.83%
They also found that for every MET improvement in fitness, middle-age participants were 17% less likely to be hospitalized for heart failure as they aged.
“It’s important to realize that the benefit of reduced heart failure hospitalization comes from sustained exercise over time,” Pandey said.
Last year, Pandey and colleagues reported results at QCOR for a similar study, but these middle-age participants had only one baseline cardiorespiratory fitness test.
The study showed that a single baseline cardiorespiratory measurement was associated with heart failure hospitalization later in life (HR 0.81, 95% CI 0.76-0.87 per 1 MET).
Researchers constructed a second model where they adjusted for the same risk factors as the first model (baseline age, sex, BMI, cholesterol, diabetes, smoking, and systolic blood pressure) and added interval development of myocardial infarction, hypertension, and diabetes.
With this model, the association between midlife cardiorespiratory fitness and heart failure risk was only minimally attenuated (HR 0.83, 95% CI 0.78-0.89).
“These results suggest that it is the direct effects of poor fitness that lead to heart failure and not that heart failure is a byproduct of other risk factors,” Pandey told MedPage Today.
He also said that higher fitness may prevent heart failure through novel protective mechanisms, which need more research to understand.
Both studies were limited because they used Medicare claims data to determine the rate of heart failure hospitalization, as well as incident hypertension, heart attack, and diabetes for the second study. Also, one or two fitness tests might not account for other changes in lifestyle over time.
Both studies received funding from the American Heart Association.
All researchers in the first study declared they had no conflicts of interest.
In the second study, de Lemos reported relationships with Abbott Diagnostics, Roche Diagnostics, and Daichi Sankyo.
From the American Heart Association: