In the population of patients with a bicuspid aortic valve (BAV), the incidence of aortic dissection over a mean of 16 years of follow-up was low, but significantly higher than in the general population, according to a study published in the Sept. 14 issue of the Journal of the American Medical Association.
BAV, the most common congenital heart defect—affecting 1.3 percent of the population—has been thought to cause frequent and severe aortic complications; however, “long-term, population-based data are lacking,” wrote the study authors.
Hector I. Michelena, MD, of the division of cardiovascular disease at Mayo Clinic in Rochester, Minn., and colleagues sought to determine the incidence of aortic complications among patients with the condition in the community as well as those in the general BAV population.
In this retrospective cohort study, the researchers conducted a comprehensive assessment of aortic complications in patients with BAV living in a population-based setting in Olmsted County, Minn. They analyzed long-term follow-up of a cohort of all Olmsted County residents diagnosed with definite BAV by echocardiography from 1980 to 1999 and searched for aortic complications of patients whose bicuspid valves had gone undiagnosed. The last year of follow-up was 2008 to 2009.
The main outcome measures were: thoracic aortic dissection, ascending aortic aneurysm and aortic surgery.
The cohort included 416 consecutive patients with definite BAV diagnosed by echocardiography; mean follow-up of 16 years (6,530 patient-years). The researchers reported that aortic dissection occurred in two of the 416 patients; an incidence of 3.1 cases per 10,000 patient-years, age-adjusted relative-risk 8.4 compared with the county's general population.
Aortic dissection incidences for patients 50 years or older at baseline and bearers of aortic aneurysms at baseline were 17.4 and 44.9 cases per 10,000 patient-years, respectively.
A comprehensive search for aortic dissections in undiagnosed bicuspid valves, according to Michelena et al, revealed two additional patients, allowing estimation of aortic dissection incidence in bicuspid valve patients irrespective of diagnosis status (1.5 cases per 10,000 patient-years), which was similar to the diagnosed cohort.
Of 384 patients without baseline aneurysms, 49 developed aneurysms at follow-up, incidence of 84.9 cases per 10,000 patient-years and an age-adjusted relative risk 86.2 compared with the general population, the authors reported. The 25-year rate of aortic surgery was 25 percent.
Despite a low incidence of dissection, patients with BAV incur significant morbidity. Additionally, aneurysm formation was 26 percent and valve replacement 53 percent for this population.
“Our study confirms that aortic valve replacement remains the most common complication of patients with BAV,” Michelena and colleagues concluded. “This highlights the importance of early recognition of BAV by careful cardiac auscultation in order to prevent heart failure due to late valvular surgery referrals, as well as potentially to prevent dissection by elective aorta surgical repair.”