A common lung condition, COPD (chronic obstructive pulmonary disease) diminishes the heart's ability to pump effectively even when the disease has no or mild symptoms, according to research published in the Jan. 21 issue of the New England Journal of Medicine.
The study is the first time researchers have shown strong links between heart function and mild COPD. The research was funded by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health.
Researchers have long known that severe cases of COPD have harmful effects on the heart, decreasing its ability to pump blood effectively. The new results suggest that these changes in the heart occur much earlier than previously believed, in mild cases and even before symptoms appear. One in five Americans over the age of 45 has COPD, but as many as half of them may not even be aware of it.
"This study shows that COPD, even in its mildest form, is associated with diminished heart function," said NHLBI Acting Director Susan B. Shurin, M.D. "We now have evidence that the presence of even mild COPD may have important health implications beyond the lungs."
COPD is the fourth leading cause of death in the United States, and it is strongly associated with smoking. COPD often involves destruction of lung tissue, called emphysema, as well as narrowed airways, persistent cough, and mucus production, known as chronic obstructive bronchitis. These abnormalities impair the flow of air in the lungs and make breathing more difficult.
Although damage to the airways from COPD is not fully reversible, treatments can substantially improve a patient's daily life. "COPD is one of the big killers in the United States, yet it is unknown to many," said James P. Kiley, Ph.D., director of the NHLBI Division of Lung Diseases. "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."
Using breathing tests and imaging studies of the chest, researchers measured heart and lung structure and function in 2,816 generally healthy adults (average age of 61 years). Study participants were part of the MESA Lung Study, an extension of the Multi-Ethnic Study of Atherosclerosis (MESA), a large, NHLBI-supported study focused on finding early signs of heart, lung, and blood diseases before symptoms appear.
Sensitive magnetic resonance imaging (MRI) and computed tomography (CT) scans uncovered mild abnormalities in heart and lung function in many participants. They discovered 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, to a lesser extent, in people with mild COPD who had never smoked.
"These results raise the intriguing possibility that treating lung disease may, in the future, improve heart function," said Graham Barr, M.D., Dr. P.H., 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. "Further research is needed to prove whether treating mild COPD will help the heart work better."
The larger MESA project involves more than 6,000 middle-aged and older men and women from six urban communities across the United States. Participants in MESA come from diverse races and ethnic groups, including African Americans, Latinos, Asians and whites. They have been tracked since enrollment began in 2000.
Because the MESA study population is ethnically mixed and covers a broad age range of apparently healthy people, the results of this study may be widely applicable to the general U.S. population.
The NHLBI also supports a national campaign, COPD Learn More Breathe Better, to help people with COPD and those at risk to become more aware of COPD, get diagnosed early, better understand this disease and live better with it.
More information about the MESA Lung Study, Endothelial Dysfunction, Biomarkers, and Lung Function (NCT00843271), can be found at http://clinicaltrials.gov/ct2/show/NCT00843271.
Materials provided by NIH/National Heart, Lung and Blood Institute. Note: Content may be edited for style and length.
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