The common lung condition, chronic obstructive pulmonary disease (COPD), brings down the heart's function even when the disorder shows no or mild symptoms, a new US study has found.
The research, funded by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health, is the first to suggest strong links between heart function and mild COPD.
Susan B. Shurin, NHLBI Acting Director, said: "This study shows that COPD, even in its mildest form, is associated with diminished heart function.
"We now have evidence that the presence of even mild COPD may have important health implications beyond the lungs."
COPD often destroys lung tissue and results in narrowed airways, persistent cough and mucus production. These conditions breathing more difficult.
James P. Kiley, director of the NHLBI Division of Lung Diseases, said: "COPD is one of the big killers in the United States, yet it is unknown to many.
"Unfortunately, many people with COPD don't recognize common symptoms such as having shortness of breath while doing activities they used to be able to do. It's important that we continue to increase awareness of the signs of COPD and available treatments."
Researchers took breathing tests and imaging studies of the chest, and measured heart and lung structure and function in 2,816 generally healthy adults (average age of 61 years).
The participants in the study were part of the MESA Lung Study, an extension of the Multi-Ethnic Study of Atherosclerosis (MESA), a large, NHLBI-supported study aimed at finding early signs of heart, lung, and blood diseases before symptoms appear.
Sensitive magnetic resonance imaging (MRI) and computed tomography (CT) scans showed mild abnormalities in heart and lung function in many participants. Scientists found that the link between lung and heart function was strongest in current smokers, who are at risk for both diseases, and especially in those with emphysema.
The findings also appeared, although to a lesser extent, in people with mild COPD who had never smoked.
Graham Barr, assistant professor of medicine and epidemiology at Columbia University Medical Center in New York City, principal investigator of the MESA Lung Study, and lead author of the paper, said: "These results raise the intriguing possibility that treating lung disease may, in the future, improve heart function.
"Further research is needed to prove whether treating mild COPD will help the heart work better."
The study has appeared in the January 21 issue of the New England Journal of Medicine.