March 20, 2010 -- A group of elite long-distance runners had less body fat, better cholesterol and blood lipid profiles, and better heart rates than people being tested for cardiac disease. Paradoxically, however, the runners had more calcified plaque in their heart arteries, according to a study reported this week.
Investigators performed computed tomography (CT) angiography on 25 people who had run at least one marathon a year since 1985, according to senior author Dr. Robert Schwartz of the Minneapolis Heart Institute and Foundation. They compared the athletes with 23 control patients who were undergoing the same scan for symptomatic or suspected heart abnormalities.
Researchers looked for the amount of calcium plaque on the inside of the subjects' arteries. Past research has suggested that the more calcium plaque inthe arteries, the higher the risk of heart attacks and death from heart disease.
In the non-runners, the calcium plaque volume was 169 cubic millimeters, compared with 274 cubic millimeters for the elite runners, the researchers reported at the American College of Cardiology meeting.
The reasons for the high-calcified plaque readings among hard-core athletes are elusive, "but the [runners'] favorable factors may be counterbalanced by metabolic and mechanical factors that enhance coronary plaque growth," suggested Dr. Jonathan Schwartz of the University of Colorado Health Science Center in Denver, lead author of the study and son of Robert Schwartz.
"You have to consider that these runners may be in a constant state of inflammation, and that may be why we are seeing more plaque," added the elder Schwartz.
He said the researchers, who originally set out to compare their results with European studies using electron beam CT, sent letters to elite runners identified as having completed at least one marathon race in each of the last 25 years. "All the runners we contacted agreed to be in the study," he noted.
The investigators also identified a control group of 23 men who were undergoing coronary CT angiography for clinical reasons, typically for elevated risk factors or abnormal or inconclusive stress tests.
The participants underwent 64-slice computed tomography angiography and were compared for blood pressure, heart rate, and serum lipids. The scan data were analyzed using commercial plaque characterization software for calcified and noncalcified plaque and calcium score.
No one is sure exactly what the plaque findings mean.
"I'm not sure you can make much from these data," said Dr. Maria Rosa Costanzo, a spokesperson for the American Heart Association and medical director of the Edward Hospital Center for Advanced Heart Failure in Naperville, Ill. "We don't have any idea of the outcomes of these patients."
She also noted that the number of patients in the study was small.
But the investigators aren't finished. "More subjects are under study for clarification of these results," said the younger Schwartz.