|
CHICAGO – While the incidence of the life-threatening
condition of aortic dissection is significantly higher than in
the general population, it remains low among patients with the
congenital heart defect, bicuspid aortic valve; however, the
incidence of aortic aneurysms is significantly high, according
to a study in the September 14 issue of JAMA.
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) is the most common congenital heart
defect, with the most serious complication from this condition
(due to the high risk of death) being aortic dissection (a tear
involving the layers of the wall of the aorta). "… 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," according to background
information in the article. However, long-term, population-based
data are lacking on the incidence of severe aortic complications
among patients with BAV.
Hector I. Michelena, M.D., of the Mayo Clinic, Rochester, M
inn., and colleagues conducted a study to determine the
incidence of aortic complications among patients with BAV and in
the general BAV population. The researchers analyzed long-term
follow-up data of residents in Olmsted County, Minn., diagnosed
with 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 2008-2009. The study
included 416 patients with BAV, with average follow-up of 16
years.
Over the study period, aortic dissection occurred in 2 of the
416 patients and the 25-year cohort risk of aortic dissection
after echocardiographic diagnosis was 0.5 percent. In a
comparison of incident rates, patients with BAV had a 8.4 times
increased risk of aortic dissection compared with the county's
general population, however, the absolute risk remained low.
"The low aortic dissection incidence and lack of association
with a detectable reduction in survival is reassuring," the
authors write.
Of 384 patients without aortic aneurysms at the beginning of the
study, 49 developed aneurysms at follow-up. The 25-year risk of
aneurysm formation among BAV patients was 26 percent. Analysis
of incidence rates indicated these patients had a 86 times
higher risk of aneurysm formation compared with the general
population. After aneurysm diagnosis, the 15-year risks of
aortic surgery and aortic dissection were 46 percent and 7
percent, respectively. The 25-year risk of aortic surgery after
BAV diagnosis was 25 percent.
The researchers also found that the dissection incidence was
higher in patients older than 50 years and higher in those with
baseline aortic aneurysms, "highlighting the importance of close
monitoring and current guideline implementation in these
subgroups."
Also, patients with BAV had a 25-year risk of valve replacement
of 53 percent. "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," the authors write.
"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," the researchers conclude.
|
