January 22, 2014 – The study, led by the DCRI’s Tariq Ahmad, MD, MPH, challenges the conventional wisdom about the benefits of exercise to heart failure patients.
Structured exercise programs do not appear to improve biomarkers among patients with chronic heart failure (HF), according to a new study published in the February issue of the American Heart Journal.
The study was conducted by the DCRI’s Tariq Ahmad, MD, MPH (pictured); Mona Fiuzat, PharmD; Daniel Mark, MD, MPH; Ben Neely, MS; Megan Neely, PhD; Christopher O’Connor, MD; and G. Michael Felker, MD, MHS.
Exercise is commonly recommended to HF patients as a way to improve functional status and reduce the risk of hospitalization. That recommendation is based largely on the results of the HF-ACTION trial, which found that exercise improved outcomes in HF patients. The exact mechanism by which exercise might do this, however, remains unclear. Recent studies have focused on the role that cardiac biomarkers, such as amino-terminal pro-brain natriuretic peptide (NT-proBNP), high-sensitivity C-reactive protein (hs-CRP), and cardiac troponin T (cTnT), play in HF. Elevated levels of these biomarkers are associated with increased chances of adverse outcomes among HF patients, but whether exercise training leads to improvements in biomarker levels and how such improvements relate to clinical outcomes remain unclear.
In this study, the researchers examined levels of NT-proBNP, hs-CRP, and cTnT in 928 patients who participated in the HF-ACTION trial. These patients were randomized to either usual HF care or a structured, group-based, supervised exercise program, with a goal of three sessions per week for a total of 36 sessions in three months. Patients in the latter group exercised primarily by walking, using a treadmill, or stationary cycling. The researchers gathered samples of all three biomarkers at the beginning of the study and again after three months.
Between the exercise training and usual care groups, there were no statistically significant differences in NT-proBNP, hs-CRP, or the proportion of patients with cTnT elevation at three months. Exercise training did not influence biomarker levels at three months, even after controlling for baseline levels of NT-proBNP or hs-CRP. Similarly, there was no association between exercise training and control groups with regard to the prevalence of elevated cTnT levels at three months. Patients who did experience a reduction in NT-proBNP levels were at less risk of death or hospitalization, and patients with improved levels of cTnT were at less risk of death. The researchers found no association between improved cTnT levels and clinical outcomes.
These findings, the researchers concluded, challenge the conventional wisdom that exercise training improves commonly evaluated cardiovascular biomarkers in patients with chronic HF. Additional research is needed to better understand the exact nature of the relationships among exercise, cardiac biomarkers, and clinical outcomes.