Natural history of asymptomatic patients with normally functioning or minimally dysfunctional bicuspid aortic valve in the community

Abstract

Background: Bicuspid aortic valve is frequent and is reported to cause numerous complications, but the clinical outcome of patients diagnosed with normal or mildly dysfunctional valve is undefined.

Methods and results: In 212 asymptomatic community residents from Olmsted County, Minn (age, 32+/-20 years; 65% male), bicuspid aortic valve was diagnosed between 1980 and 1999 with ejection fraction > or =50% and aortic regurgitation or stenosis, absent or mild. Aortic valve degeneration at diagnosis was scored echocardiographically for calcification, thickening, and mobility reduction (0 to 3 each), with scores ranging from 0 to 9. At diagnosis, ejection fraction was 63+/-5% and left ventricular diameter was 48+/-9 mm. Survival 20 years after diagnosis was 90+/-3%, identical to the general population (P=0.72). Twenty years after diagnosis, heart failure, new cardiac symptoms, and cardiovascular medical events occurred in 7+/-2%, 26+/-4%, and 33+/-5%, respectively. Twenty years after diagnosis, aortic valve surgery, ascending aortic surgery, or any cardiovascular surgery was required in 24+/-4%, 5+/-2%, and 27+/-4% at a younger age than the general population (P<0.0001). No aortic dissection occurred. Thus, cardiovascular medical or surgical events occurred in 42+/-5% 20 years after diagnosis. Independent predictors of cardiovascular events were age > or =50 years (risk ratio, 3.0; 95% confidence interval, 1.5 to 5.7; P<0.01) and valve degeneration at diagnosis (risk ratio, 2.4; 95% confidence interval, 1.2 to 4.5; P=0.016; >70% events at 20 years). Baseline ascending aorta > or =40 mm independently predicted surgery for aorta dilatation (risk ratio, 10.8; 95% confidence interval, 1.8 to 77.3; P<0.01).

Conclusions: In the community, asymptomatic patients with bicuspid aortic valve and no or minimal hemodynamic abnormality enjoy excellent long-term survival but incur frequent cardiovascular events, particularly with progressive valve dysfunction. Echocardiographic valve degeneration at diagnosis separates higher-risk patients who require regular assessment from lower-risk patients who require only episodic follow-up.

Figure 1

Echocardiographic short-axis views in systole at aortic cusps’ levels in two patients with bicuspid aortic valves. In A is shown a patient with no valve degeneration with in B the same image superimposed with the drawing of the large valve orifice (white area). Arrowheads mark the commissures; A: Anterior cusp; P: posterior cusp; LA: Left atrium; RA: Right Atrium, RV: Right Ventricle. In C is shown a patient with valve degeneration (large arrow) involving mostly the anterior cusp with large orifice area drawn in D (white area). Labeling is similar to image A.

Figure 2

Survival after diagnosis of asymptomatic community members with bicuspid aortic valve (solid line) compared to the expected survival in the same community (dashed line). The numbers at the bottom indicate the patients at risk for each interval. The survival (±SE) is indicated 20 years after diagnosis.

Figure 3

Incidence of total medical events (cardiac death, congestive heart failure, new cardiac symptoms, stroke and endocarditis; solid line), new cardiac symptoms (dyspnea, cardiac chest pain and syncope; dashed line) and congestive heart failure (CHF; dotted line). The numbers at the bottom indicate the patients at risk for each interval. The event rates (±SE) are indicated at 20 years.

Figure 4

Incidence of total surgical events (aortic valve, ascending aorta, aortic coarctation; solid line), of aortic valve surgery (aortic valve replacement or surgical valvotomy; dashed line), of ascending aortic surgery (dashed and dotted line) and aortic coarctation surgery (dotted line). The numbers at the bottom indicate the patients at risk for each interval. The event rates (±SE) are indicated at 20 years.

Figure 5

Incidence of any cardiovascular event (total of medical or surgical; solid line), of medical events (cardiac death, congestive heart failure, new cardiac symptoms, stroke and endocarditis; dashed line) and of surgical events (aortic valve replacement, surgical valvotomy, ascending aorta surgery or coarctation surgery; dotted line). The numbers at the bottom indicate the patients at risk for each interval. The event rates (±SE) are indicated at 20 years.

Figure 6

Incidence of events during follow-up according to the presence or absence of valve degeneration at diagnosis (defined as score ≥3 or <3). A-Left graph: Incidence of aortic valve surgery according to baseline valve degeneration at diagnosis. At 12 years aortic valve surgery was 75±10% with and 8±2% without valve degeneration at diagnosis. B-Right graph: Medical event rates according to baseline valve degeneration at diagnosis demonstrating the high medical events rate in patients who display valve degeneration at diagnosis at baseline.