Rationale and Objectives
The aim of this study was to evaluate the role of incidental aortic valve calcification on routine computed tomographic scans as a marker for stenosis, as assessed by echocardiography, in patients with bicuspid aortic valve (BAV) and tricuspid aortic valve.
Materials and Methods
Computed tomographic and echocardiographic studies were retrospectively reviewed for 182 consecutive, unselected patients and 426 patients identified by a record search for “aortic valve calcification.” Location and severity of valve calcification were correlated with aortic valve morphology and stenosis. Differences between subgroups were assessed using χ 2 or Fisher’s exact tests.
Results
In unselected patients, calcification was present in 25.8% with tricuspid aortic valves (46 of 178) and 75% (three of four) with BAV. In patients selected for valve calcification, the average age of those with tricuspid aortic valves ( n = 395) was 14.3 years older than those with BAV ( n = 31). Patients with BAV were more likely to have severe calcification (87% vs 50%, P < .001), and if severe calcification was present, it was more likely to involve only the valve leaflets (41% vs 9%, P < .001) and result in aortic stenosis (85% vs 58%, P = .006). Patients aged < 60 years with severe calcification were more likely to have BAV (56% vs 7%; odds ratio, 7.9; 95% confidence interval, 3.4–18.7).
Conclusions
Aortic valve calcification was found 14 years earlier in patients with BAV and was more severe and strongly linked to aortic stenosis. Valve calcification on computed tomographic scans should be considered a marker for BAV if found before the seventh decade.
Aortic valve calcification identified on computed tomographic (CT) scans has been studied as a marker for stenosis of tricuspid aortic valve (TAV), but its significance for bicuspid aortic valve (BAV) is not well established. In studies principally of TAV, the severity of valve calcification as assessed by qualitative and quantitative CT methods correlates with increased degree of aortic stenosis . Marked valve calcification predicts adverse clinical outcomes. Older studies with other imaging modalities have demonstrated a clear link between increased degree of aortic valve calcification and the progression of aortic stenosis, need for aortic valve replacement, and death . Minor aortic valve calcification, however, is a common finding on multi–detector row computed tomography that is often hemodynamically insignificant . Whether these findings apply to BAV disease as well has not been studied directly.
BAV is relatively common (1%–2% of the population) and progresses to aortic stenosis in the majority of patients . Nearly half of isolated aortic valve replacements for aortic stenosis are attributed to BAV . Because aortic stenosis develops rapidly and is seen 10 to 15 years earlier than in patients with TAV , improving the early detection of BAV by imaging before advanced aortic valve disease ensues could significantly aid the clinical management of these patients. Aortic valve calcification is an attractive marker for BAV. Not only is it a common incidental finding on CT scans that is easily interpreted by radiologists, but also it is seen at younger ages with BAV than with TAV. Advanced aortic valve calcification has been reported with BAV in patients aged < 30 years and with 100% incidence by the seventh decade .
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Materials and methods
Patients
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Table 1
Patient Characteristics
Variable Unselected Selected for Aortic Valve Calcification TAV BAV TAV BAV_n_ 178 4 395 31 Age (y) 58.5 ± 16.4 63.8 ± 12.8 73.6 ± 12.5 59.3 ± 14.6 Men 107 4 228 21 Aortic valvular disease Insufficiency Mild 9 1 112 11 Moderate/severe 4 1 24 6 Stenosis Mild 2 1 47 7 Moderate/severe 5 1 101 17 Calcification Nonsevere Annular 11 0 23 0 Leaflet 14 0 45 3 Both 14 0 129 1 Severe ∗ 7 3 198 27
BAV, bicuspid aortic valve; TAV, tricuspid aortic valve.
Data are expressed as numbers or as mean ± standard deviation.
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Multi–detector Row CT Imaging
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Image Interpretation
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Echocardiography
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Statistical Analysis
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Results
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Aortic Valve Calcification in Unselected Patients
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Table 2
Presence of Calcification in Unselected Patients
Variable TAV BAV Patients 178 4 Calcification 46 3 Percentage with calcification 25.8% 75.0% Severe ∗ 7 3 Percentage with severe calcification 3.9% 75.0%
BAV, bicuspid aortic valve; TAV, tricuspid aortic valve.
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Patients Selected for Aortic Valve Calcification
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Table 3
Degree of Aortic Stenosis by Valve Type and Degree of Calcification
Variable Patients No Stenosis Mild Stenosis Marked Stenosis BAV nonsevere calcification 4 3 (75%) 1 (25%) 0 (0%) Annular 0 0 (0%) 0 (0%) 0 (0%) Leaflet 3 3 (100%) 0 (0%) 0 (0%) Both 1 0 (0%) 1 (100%) 0 (0%) BAV severe calcification 27 4 (15%) 6 (22%) 17 (63%) TAV nonsevere calcification 197 164 (83%) 20 (10%) 13 (7%) Annular 23 23 (100%) 0 (0%) 0 (0%) Leaflet 45 41 (91%) 3 (7%) 1 (2%) Both 129 100 (78%) 17 (13%) 12 (9%) TAV severe calcification 198 83 (42%) 27 (14%) 88 (44%)
BAV, bicuspid aortic valve; TAV, tricuspid aortic valve.
Table 4
BAV Versus TAV with Valve Calcification by Age
Age Group (y) BAV TAV ( n = 31) ( n = 395) <40 10% (3) 1% (4) 40–49 6% (2) 4% (14) 50–59 39% (12) 9% (35) 60–69 23% (7) 18% (73) 70–79 16% (5) 29% (115) 80–89 3% (1) 33% (131) >89 3% (1) 6% (23)
BAV, bicuspid aortic valve; TAV, tricuspid aortic valve.
Data are percentages (numbers) of total patients of each valve type in each age group.
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Aortic Valve Calcification and Degree of Aortic Stenosis
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Table 5
Degree of Aortic Stenosis by Location of Calcification
Variable Patients No Stenosis Mild Stenosis Marked Stenosis Nonsevere calcification 201 167 (83%) 21 (10%) 13 (6%) Annular 23 23 (0%) 0 (0%) 0 (0%) Leaflet 48 44 (92%) 3 (6%) 1 (2%) Both 130 100 (77%) 18 (14%) 12 (9%) Severe calcification 225 87 (39%) 33 (15%) 105 (47%)
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Aortic Valve Calcification Location and Stenosis
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Discussion
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