February 1, 2010

Mild Lung Disease Linked to Heart Function

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People with a mild form of a common lung condition—even those without symptoms—are at increased risk for heart problems, according to a new study. This is the first report that mild, often-symptomless chronic obstructive pulmonary disease (COPD) may be linked to the heart's pumping ability.

COPD is the nation's fourth leading cause of death. It affects an estimated 1 in 5 Americans over age 45, but as many as half the people who have it may not even be aware of it. The condition is strongly associated with smoking, and it often involves the destruction of lung tissue, called emphysema. COPD can bring persistent coughing, mucus production, wheezing, shortness of breath and chest tightness. Symptoms often worsen over time.

Researchers have long known that severe COPD can have harmful effects on the heart, decreasing its ability to pump blood effectively. To see if mild and even symptomless COPD might also be linked to reduced heart function, a team of scientists led by Dr. Graham Barr of Columbia University Medical Center studied 2,816 generally healthy adults ages 45 and older. About half were women. All were participants in the Multi-Ethnic Study of Atherosclerosis (MESA), a large study designed to detect early signs of heart, lung and blood diseases before symptoms appear. MESA is supported by NIH's National Heart, Lung, and Blood Institute (NHLBI).

As described in the January 21, 2010, issue of the New England Journal of Medicine, the researchers used breathing tests and imaging studies of the chest to assess the structure and function of each person's heart and lungs. None of the participants had severe COPD or heart disease, but many were found to have mild abnormalities in heart and lung function.

The scientists observed that as lung function and structure became increasingly impaired, so did the heart's ability to fill with oxygen-rich blood. The volume of blood pumped per minute also dropped as lung function declined. The link between lung and heart function was strongest in the 370 participants who were current smokers, but it was also seen in people with mild COPD who had never smoked.

The new results suggest that these changes in heart function occur much earlier than previously realized, when COPD is mild or even before symptoms appear. Because the study population was ethnically mixed and covered a broad age range of apparently healthy people, the findings may be widely applicable to the general U.S. population.

"These results raise the intriguing possibility that treating lung disease may, in the future, improve heart function," says Barr. "Further research is needed to prove whether treating mild COPD will help the heart work better."

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