According to an investigation in the September 14 issue of JAMA, although the prevalence of the life-threatening condition of aortic dissection is considerably higher than in the general population, among individuals with congenital heart defect, bicuspid aortic valve, it remains low, but, the prevalence of aortic aneurysms is considerably high.
The most common heart defect is bicuspid aortic valve (BAV; defect of the aortic valve that results in the formation of two flaps that open and close, instead of the normal three). Because of the high risk of death, the most severe complication from this defect is aortic dissection (a tear involving the layers of the wall of the aorta). According to background data in the report: “it is estimated that BAV is responsible for more deaths than all other congenital heart defects combined. Consequently, carriers live under the threat of sudden death.” Yet, the prevalence of severe aortic complications among individuals with BAV is lacking in long-term population-based data.
Hector I. Michelena, M.D., of the Mayo Clinic, Rochester, M inn., and colleagues conducted an investigation to find out the prevalence of aortic complications among those with BAV and in the general BAV population. Long-term follow-up data of residents in Olmsted County, Minn., diagnosed with BAV by echocardiography from 1980 to 1999 was examined by the researchers, and they searched for aortic complications of patients whose bicuspid valves had gone undiagnosed. The investigation consisted of 416 patients with BAV, with average follow-up of 16 years. The last year of follow-up was 2008-2009.
Aortic dissection occurred in two of the 416 participants, over the study period, and the 25-year cohort risk of aortic dissection after echocardiographic diagnosis was 0.5%. The incident rate among patients with BAV of aortic dissection was 8.4 times higher in comparison with the general population of the county, although the absolute risk of aortic dissection stayed low. The researchers wrote:
“The low aortic dissection incidence and lack of association with a detectable reduction in survival is reassuring.”
Of the 384 participants without aortic aneurysms at the start of the investigation, at follow up, 49 developed aneurysms. The 25-year risk of aneurysm among those with BAV was 26%. An evaluation of incidence rates suggested that these patients, in comparison with the general population, had an 86 times higher risk of aneurysm formation. Following an aneurysm diagnosis, the 15-year risks of aortic surgery and aortic dissection were 46% and 7%, respectively. The 25-year risk of aortic surgery following BAV diagnosis was 25%.
They also discovered that in patients over 50 the dissection incidence was greater, as well as in those with baseline aortic aneurysms, “highlighting the importance of close monitoring and current guideline implementation in these subgroups.”
In addition individuals with BAV also had a 25-year risk of valve replacement of 53%.
The researchers explain:
“Our study confirms that aortic valve replacement remains the most common complication of patients with BAV. This highlights the importance of early recognition of BAV by careful cardiac auscultation [listening for sounds made by internal organs to aid in the diagnosis of certain disorders] in order to prevent heart failure due to late valvular surgery referrals, as well as potentially to prevent dissection by elective aorta surgical repair.”
(conclusion) Research efforts should concentrate on elucidating biological pathways of BAV aortopathy [disease of the aorta] amenable to medical treatment, as well as identifying nonsize markers for refining risk prediction of aortic dissection in these patients.”
Written by Grace Rattue