A Diagnostic Pitfall of CT Calcium Scoring in Paradoxical Low-Flow, Low-Gradient Severe Aortic Stenosis With Rheumatic Morphology: a case report

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  Figure 1. Electrocardiographic findings at presentation. A 12-lead electrocardiogram showed atrial fibrillation, incomplete right bundle branch block, and left ventricular high voltage with ST-segment depression and T-wave inversion in leads II, III, aVF, V5, and V6, consistent with a strain pattern.

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  Figure 2. Transthoracic echocardiographic findings at presentation. (A) Parasternal long-axis view showing concentric left ventricular remodelling with increased wall thickness and a thickened aortic valve. Left ventricular systolic function was preserved. (B) Parasternal short-axis view of the aortic valve showing a tricuspid configuration. Delineation of the valvular orifice was suboptimal on transthoracic imaging, although restricted opening was suggested. (C) Pulsed-wave Doppler of the left ventricular outflow tract, from which the stroke volume index was calculated as 30 mL/m2, indicating a low-flow state. (D) Continuous-wave Doppler across the aortic valve showing a peak aortic valve velocity of 3.57 m/s. Taken together, these findings were consistent with suspected paradoxical low-flow, low-gradient severe aortic stenosis. AV = aortic valve; LA = left atrium; LCC = left coronary cusp; LV = left ventricle; NCC = non-coronary cusp; RCC = right coronary cusp; SVI = stroke volume index.

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  Figure 3. Computed tomography findings showing discordantly low calcium burden and rheumatic morphologic features of the aortic valve. (A) Non-contrast computed tomography-based aortic valve calcium scoring showed an Agatston score of 889 AU, which was below the usual threshold supporting severe calcific aortic stenosis. (B) Contrast-enhanced short-axis computed tomography image of the aortic valve showing a restricted valvular opening with leaflet tip thickening (yellow arrowheads) and focal calcification (green arrows), with limited overall calcific burden. These findings were suggestive of rheumatic morphology rather than typical bulky degenerative calcification. AU = Agatston units; LCC = left coronary cusp; NCC = non-coronary cusp; RCC = right coronary cusp.

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  Figure 4. Simultaneous left ventricular and aortic pressure tracings during cardiac catheterization. Simultaneous invasive haemodynamic assessment showed a mean transvalvular pressure gradient of 34.8 mmHg. Ao = aorta; LV = left ventricle; PG = pressure gradient.

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  Figure 5. 3D transoesophageal echocardiography showing rheumatic morphology and anatomy-based confirmation of severe aortic stenosis. (A) En face 3D transoesophageal echocardiographic view of the aortic valve showing a restricted triangular orifice with commissural fusion (red arrowheads) and leaflet tip thickening (blue arrows). (B, C) Orthogonal multiplanar reconstruction views used to align the aortic valve at the level of the smallest valvular orifice. (D) Direct planimetry on multiplanar reconstruction showing an aortic valve area of 0.69 cm2, consistent with severe aortic stenosis. Ao = aorta; AVA = aortic valve area; LCC = left coronary cusp; LV = left ventricle; NCC = non-coronary cusp; RCC = right coronary cusp.