Abstract 18071: Integrating Three-Dimensional Imaging for Aortic Valve Stenosis Assessment. A Pilot Multimodality Imaging Study Comparing Classic vs. Paradoxical Low-Flow, Low-Gradient Severe Aortic Stenosis

BACKGROUND: Assessment of aortic stenosis (AS) severity is critical for treatment decisions but challenging in patients with severe AS (aortic valve area, AVA <1.0 cm2) and low gradients (mean AV gradient <40 mmHg). We sough to evaluate the incremental utility of 3D multidetector computed tomography (MDCT) over TTE for assessment of AS severity in patients with either depressed (classic low-flow, low-gradient, CLFLG, LVEF <50%) or preserved LV systolic function (paradoxical low-flow, low-gradient, PLFLG, LVEF ≥50%) is unknown. METHODS: Sixteen patients who underwent TTE, invasive hemodynamics with a right heart catheterization and dual lumen pigtail catheter, and MDCT studies within 30 days were prospectively studied (10 CLFLG and 6 PLFLG). Mean age was 76±10 years with 26% females. TTE parameters included LVEF, systolic LVOT diameter (LVOT-D) and conventional AV Doppler assessment. MDCT evaluated ratio of maximal to minimal LVOT-D (eccentricity index), mean systolic LVOT-D, and AVA by planimetry. Corrected AVA was calculated by substituting the MDCT-derived mean LVOT-D into continuity equation (MDCT-AVA). RESULTS: Figure 1 shows hemodynamics and imaging parameters measured. Despite good correlation between TTE-AVA and MDCT-AVA (r=0.85, p<0.0001), AVA was underestimated in 10/16 of patients by either TTE or invasive hemodynamics, irrespective of the baseline LVEF (p < 0.0001 for both). Dimensionless index also correlated better with MDCT-AVA (r=0.71, p=0.002) then with TTE-derived AVA (r=0.58, p=0.003) or by cath-derived AVA (r=0.47, p=0.02). CONCLUSION: In patients with severe AS and low-gradients, MDCT imaging revealed eccentric LVOT in most patients, resulting in underestimation of 2D TTE-AVA. Integration of 3D imaging dataset with either 3D-transesophageal echocardiography or MDCT may improve AS severity classification of these challenging patients. Larger cohort studies will be needed to ascertain the impact on treatment decisions.