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

Aortic valve area (AVA) using CT-LVOT area (AVACT-LVOT) <1.2 ​cm2 has been shown comparable to echocardiography AVA of <1.0 ​cm2 for severe aortic stenosis (AS). Current study evaluates how AS diagnosis will be affected when we substitute CT-LVOT with echo derived LVOT.We retrospectively studied 367 patients who underwent cardiac CTA and echocardiogram for assessment of high- and low-gradient AS (HG-AS and LG-AS). AVACT-LVOT was derived from CT-LVOT area and echo doppler data. Three AVACT-LVOT categories were created (<1.0, 1.0-1.2 and ​> ​1.2 ​cm2). Outcomes were defined as composite of all-cause mortality and/or valve intervention.Median echocardiographic profiles were consistent with severe AS across three AVACT-LVOT categories for HG-AS. HG-AS patients with AVACT-LVOT >1.2 ​cm2 had larger median CT-LVOT area (5.06 ​cm2) and AVC (2917AU). Among LG-AS with AVACT-LVOT ​≤1.2 cm2, 57% met echo criteria for low-flow LG-AS and 63% met criteria for severe AS using aortic valve calcium (AVC). Additionally, 45% with AVACT-LVOT >1.2 ​cm2 had larger median CT-LVOT area (5.43 ​cm2) and AVC (2389AU). Patients with AVACT-LVOT >1.2 ​cm2 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 AVACT-LVOT ≤1.2 ​cm2 (p ​< ​0.01), however, with no superior net reclassification improvement compared to AVAecho <1.0 ​cm2.AVACT-LVOT ≤1.2 ​cm2 is a reasonable CT criterion for severe AS. Large LVOT with elevated AVC identified a severe AS phenotype despite an AVACT-LVOT >1.2 ​cm2, best characterized by indexed AVA and AVC.