Why Exercise Helps Heart Failure Patients
Aerobic training program and heart
Aerobic training is associated with a reversal of abnormal hormonal patterns that underlie many of the debilitating symptoms of heart failure, according to a new study in the May 2, 2006, issue of the Journal of the American College of Cardiology.
"A feasible home-based and progressively adjusted aerobic training strategy is able to overcome the limitation of pharmacological treatment in antagonizing neurohormonal activation in heart failure patients, likely contributing to a significant improvement in quality of life, and possibly to the positive prognostic effects," said Claudio Passino, M.D. from the CNR Institute of Clinical Physiology in Pisa, Italy.
It is well-known that exercise training helps many heart failure patients feel better and improves their ability to function more normally. This study indicates that aerobic training may produce these benefits by reversing the abnormal production of certain neurohormones that result in many of the severe symptoms of heart failure.
After a heart attack or other cardiac event, the body responds by increasing the production of B-type natriuretic peptide (BNP). This neurohormonal activation, as it is called, helps the heart continue to pump blood in the short run by constricting blood vessel and retaining sodium in cardiac cells.
"This neurohormonal imbalance becomes detrimental on the long-term, promoting left ventricular fibrosis, dilatation, arrhythmias, peripheral tissue hypoperfusion, edemas, and thus leading to a symptomatic disease with dyspnea and fatigue," Dr. Passino said.
Previous studies indicated that patients with higher levels of B-type natriuretic peptide have poorer prognoses. Drug treatments are often unable to adequately reverse the neurohormonal activation.
Since physical activity often helps heart failure patients, the researchers wanted to find out what effect aerobic training has on the neurohormonal imbalance. They randomized heart failure patients into two groups. The treatment group consisted of 47 patients who entered a nine-month aerobic training program that progressively increased the amount of work the patients were able to perform. The control group of 48 patients received standard heart failure treatments, but no physical training.
The 44 patients who completed the training program improved their fitness and said their quality of life was better than the 41 patients who completed the control group arm of the study. But in addition, the patients who worked out had decreased levels of three key hormones, B-type natriuretic peptide (BNP), amino-terminal pro-brain natriuretic peptide (NT-proBNP), and norepinephrine.
Dr. Passino said the results indicate that aerobic training may be able to restore neurohormonal balance in a way that may improve on current drug therapies.
"Reversing neurohormonal activation by physical training adds to the current clinical practice a novel non-pharmacological aid. Out of 85 patients who completed the protocol, only the 44 randomized to the training program improved functional capacity, systolic function, and quality of life, in contrast to the controls. These beneficial effects were associated with a decrease in plasma level of BNP, NT-proBNP, and norepinephrine, only in the training group," he said.
In addition, he said that the measurements of neurohormonal activation used in this study may be a useful way for physicians to assess the effect of training in their patients.
John Floras, M.D., D.Phil., F.R.C.P.C. from the University of Toronto in Canada, who was not connected with this study, said the results provide additional evidence of the benefits of exercise for selected heart failure patients, while offering fresh insight into how training works to provide those benefits.
"While an acute bout of exercise will lead to increases in both norepinephrine and BNP, with chronic training plasma concentrations of these factors diminish, suggesting that exercise training modulates beneficially activation of several neurohumoral pathways that reflect the severity of heart failure, and that following BNP concentrations may be one way of assuring that long term exercise training programs are having beneficial effects in individual patients. Pending is evidence from large randomized clinical trials that such short term changes will translate, over time, into mortality benefits for patients with chronic heart failure," Dr. Floras said.