Abstract 10725: Computed Tomography Evaluation of LV Outflow Tract: Impact on Survival in Aortic Stenosis
Background: It is well established that LV outflow tract (LVOT) is not circular and that 2D echocardiography annular measurement may not accurately assess LVOT area. However, the impact of this potential underestimation on survival after aortic stenosis (AS) diagnosis has not been addressed. We aimed at evaluating whether LVOT area measured by MDCT for aortic valve area (AVA) calculation provides incremental value over standard Doppler AVA calculation in determining survival after diagnosis.
Method: 269 patients with at least mild calcific AS underwent TTE and MDCT within an interval of 3 months. Aortic valve area (AVA) was calculated by Doppler (continuity equation) using annular area and by MDCT using LVOT area in the continuity equation (AVA_CT).
Results: The patients were 76±11 years old and 106 (39%) were women. The mean AVA was 0.94±0.32cm2, AVA_CT 1.13±0.44cm2, mean gradient 44±18mmHg and LV ejection fraction 58±14%. During follow-up of 3.1±2.5 years, there were 164 Aortic Valve Replacements (AVR) and 90 deaths. AVA_CT was larger than AVA in 230 (86%) patients with a mean difference of 0.19±0.20 cm2. Two multivariate models were constructed, one with AVA and one with AVA_CT and adjusted for age, gender, coronary artery disease, diabetes, presence of symptoms, mean gradient, LV ejection fraction and AVR (as a time dependent variable). AVA and AVA_CT were independent predictor of survival (HR=0.23; 95%CI=0.07-0.75; p=0.01 and HR=0.30; 95%CI=0.13-0.69; p=0.004, respectively) with similar accuracy of 2 models (Khi-square: 63.6; p<0.0001 vs. Khi-square: 65.3; p<0.0001, respectively; p=0.23 by C statistics). However, the thresholds defining mortality were highly different: AVA ≤1cm2 was independently predictive of mortality (HR=2.51; 95%CI=1.28-4.92; p=0.007) while AVA_CT≤1cm2 was not (p=0.08). The best threshold of AVA_CT predicting mortality was 1.2 cm2 (HR=2.16; 95%CI=1.16-4.01; p=0.01).
Conclusion: AVA calculated using LVOT area measured by MDCT is larger than AVA by Doppler-echocardiography. However, the threshold predicting an excess mortality after AS diagnosis was also larger (1.2 vs. 1 cm2) and the accuracy for risk stratification appears equivalent.
- © 2013 by American Heart Association, Inc.