Multimodality assessment of high- vs. low-gradient aortic stenosis using echocardiography and cardiac CT

Background: Aortic valve area (AVA) using CT-LVOT area (AVA(CT-LVOT)) <1.2 cm(2) has been shown comparable to echocardiography AVA of <1.0 cm(2) for severe aortic stenosis (AS). Current study evaluates how AS diagnosis will be affected when we substitute CT-LVOT with echo derived LVOT.Methods: We retrospectively studied 367 patients who underwent cardiac CTA and echocardiogram for assessment of high- and low-gradient AS (HG-AS and LG-AS). AVA(CT-LVOT) was derived from CT-LVOT area and echo doppler data. Three AVA(CT-LVOT) categories were created (<1.0, 1.0-1.2 and > 1.2 cm(2)). Outcomes were defined as composite of all-cause mortality and/or valve intervention.Results: Median echocardiographic profiles were consistent with severe AS across three AVA(CT-LVOT) categories for HG-AS. HG-AS patients with AVA(CT-LVOT) >1.2 cm(2) had larger median CT-LVOT area (5.06 cm(2)) and AVC (2917AU). Among LG-AS with AVA(CT-LVOT) <= 1.2 cm(2), 57% met echo criteria for low-flow LG-AS and 63% met criteria for severe AS using aortic valve calcium (AVC). Additionally, 45% with AVA(CT-LVOT) >1.2 cm(2) had larger median CT-LVOT area (5.43 cm(2)) and AVC (2389AU). Patients with AVA(CT-LVOT) >1.2 cm(2) and high AVC had large body surface area and were mostly characterized as severe with indexed AVA and AVC. Stroke volume index using CT-LVOT reclassified 70% of low-flow, LG-AS as normal flow, LG-AS. Composite outcomes were higher among patients with AVA(CT-LVOT) <= 1.2 cm(2) (p < 0.01), however, with no superior net reclassification improvement compared to AVA(echo) <1.0 cm(2).Conclusion: AVA(CT-LVOT) <= 1.2 cm(2) is a reasonable CT criterion for severe AS. Large LVOT with elevated AVC identified a severe AS phenotype despite an AVA(CT-LVOT) >1.2 cm(2), best characterized by indexed AVA and AVC.