Author + information
- Sreekanth R. Kondareddy,
- Edo Kaluski,
- Mansi Kallem,
- Maninder Singh and
- Abhishek Kulkarni
Trans thoracic echocardiographic (TTE) assessment of aortic stenosis (AS) severity and cardiac output measurements are affected by the left ventricular outflow tract (LVOT) area typically calculated based on a single diameter measured in the parasternal long axis view.
To evaluate the correlation between the left ventricular outflow tract (LVOT) area measured by coronary CT angiogram (CCTA) and the LVOT area computed from TTE using the LVOT diameter in subjects with severe AS.
Retrospective analysis of 34 patients with severe AS. CCTA and TTE were performed within a period of 60 days in subjects evaluated for transcatheter aortic valve replacement (TAVR). The LVOT area by CCTA was obtained by direct planimetry and is compared to LVOT area computed by TTE using the LVOT diameter.
The mean LVOT area by TTE and CCTA was 4.06 cm2 (range 2.48 -5.63 cm2) and 4.73 cm2 (range 3.34 -7.40 cm2) respectively. LVOT area obtained by CCTA was consistently higher by 0.67 ± 0.35 cm2 or 22 ± 20% than the TTE derived LVOT area (Fig 1). The diameter to derive the LVOT area by CCTA varies with TTE by 1.8 ± 2.4 mm with 95% C.I. The discrepancy between these two modalities increases with higher BSA with a correlation coefficient of 0.59.
TTE-based LVOT consistently underestimates the actual 3-dimensional LVOT area based on CCTA. The difference in the diameter is driven by the elliptical shape of LVOT with larger lateral diameter that is not measured by the TTE. Consequently TTE systematically underestimates cardiac output and index and overestimates aortic valve area.