Bone mineral loss seen in men after heart surgery

NEW YORK (Reuters Health) - In the year following coronary artery bypass grafting (CABG), bone mineral content declines significantly in men, according to findings published in the American Journal of Cardiology. Declines in bone mineral have been shown to increase the risk of fracture.

Dr. Larry E. Miller, of Virginia Polytechnic Institute and State University, and colleagues evaluated changes in bone mineral and body composition in 26 men, between the ages of 50 and 79 years, who underwent CABG. In each patient, blockages were removed in more than one coronary artery, the blood vessels that pass through the heart to provide oxygen-infused blood to the rest of the body.

The investigators performed dual-energy X-ray absorptiometry, a method of measuring bone mineral content, before surgery and at 3 months and 1 year after treatment.

Bone mineral density had decreased in the arms, pelvis and the total body by 3 months after treatment. The bone mineral content was also reduced by 4.9 percent in the arms, and losses in the legs and total body approached statistical significance.

There were also statistically significant decreases in fat-free mass in the arms and total body, but not in the legs. No changes in total body or regional fat mass were detected.

Of the 26 subjects, 15 returned for 1-year follow-up. Bone mineral density in the total body and the legs was still significantly decreased, and it was also decreased in the arms.

There were no changes observed in total body or regional body composition by the 1 year after treatment period.

"Because there is a strong correlation between bone mineral and fracture risk, CABG patients may be at increased risk for osteoporotic fractures unless preventative steps are taken to minimize bone losses," Miller commented to Reuters Health. "Cardiac rehabilitation, which includes upper body flexibility exercises, should be undertaken as soon as possible post-CABG surgery in appropriate patients," he advised.

"Formalized low-intensity resistance training regimens should be initiated later (approximately 3 to 4 months) in low-moderate risk patients and only after the sternum is fully healed," Miller recommended. The sternum, or breast bone, is the flat bone in the chest that the heart surgeon must cut through to get to the damaged arteries.

"This regimen may prevent or slow the dramatic bone mineral losses that were observed in our study."

SOURCE: American Journal of Cardiology, March 2007.