Also, after an aneurysm was found, the risk of aortic surgery over the next 15 years was 46 percent, and the risk of aortic dissection was 7 percent. Over 25 years, the risk of having an operation connected to bicuspid aortic valve was 25 percent, they said.
Those at the highest risk for an aortic dissection were patients over 50 and those with aortic aneurysms, Michelena's group noted. The 25-year risk for needing a valve replacement -- the most common complication -- was 53 percent, they added.
Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles, said that between 1 percent and 2 percent of the population have bicuspid aortic valves. Many patients have no problems, but some develop blockage or leakage of the valve and some have abnormalities of the aorta that may result in aortic dissection. The frequency of this complication has not been well-studied, Fonarow said.
This study indicates that the absolute risk for this problem is very low, at three per 10,000 patient years of follow-up, he said.
"These findings are reassuring and suggest that the rate of aortic dissection among individuals with bicuspid aortic valves, while significantly higher than the general population, are still quite low in absolute terms," Fonarow said.
For more information on bicuspid aortic valves, visit the U.S. National Library of Medicine.
SOURCES: Hector I. Michelena, M.D., assistant professor, medicine, Mayo Clinic, Rochester, Minn.; Gregg Fonarow, M.D., professor, cardiology, University of California, Los Angeles; Sept. 14, 2011, Journal of the American Medical Association
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