Integration of 3D Imaging Data in the Assessment of Aortic Stenosis Impact on Classification of Disease Severity

Background-In patients with aortic stenosis (AS), precise assessment of severity is critical for treatment decisions. Estimation of aortic valve area (AVA) with transthoracic echocardiographic (TTE)-continuity equation (CE) assumes a circular left ventricular outflow tract (LVOT). We evaluated incremental utility of 3D multidetector computed tomography (MDCT) over TTE assessment of AS severity. Methods and Results-We included 51 patients (age, 81 +/- 8 years; 61% men; mean gradient, 42 +/- 12 mm Hg) with calcific AS who underwent evaluation for treatment options. TTE parameters included systolic LVOT diameter (D) and continuous and pulsed wave (CW and PW) velocity-time integrals (VTI) through the LVOT and mean transaortic gradient. MDCT parameters included systolic LVOT area, ratio of maximal to minimal LVOT diameter (eccentricity index), and aortic planimetry (AVA(p)). TTE-CE AVA [(D-2 x 0.786 x VTIpw)/VTIcw] and dimensionless index (DI) [VTIpw/VTIcw] were calculated. Corrected AVA was calculated by substituting MDCT LVOT area into CE. The majority (96%) of patients had eccentric LVOT. LVOT area, measured on MDCT, was higher than on TTE (3.84 +/- 0.8 cm(2) versus 3.03 +/- 0.5 cm(2), P < 0.01). TTE-AVA was smaller than AVAp and corrected AVA (0.67 +/- 0.1cm(2), 0.82 +/- 0.3 cm(2), and 0.86 +/- 0.3 cm(2), P < 0.01). Using TTE measurements alone, 73% of patients had congruence for severe AS (DI <= 0.25 and CE AVA < 0.8 cm(2)), which increased to 92% using corrected CE. Conclusions-In patients with suspected severe AS, incorporation of MDCT-LVOT area into CE improves congruence for AS severity. (Circ Cardiovasc Imaging. 2011;4:566-573.)