Dynamic conformational changes of the left ventricular outflow tract compared to the aortic annulus and implications on transcatheter aortic valve selection and sizing
Aljamal AO, Alalwan Y, Coriasso N, Hughes C, Abdelrahim E, Lee JC, Wang DD, Pantelic M, Song T, Eng M, Frisoli TM, Villablanca P, and Wyman JF. Dynamic conformational changes of the left ventricular outflow tract compared to the aortic annulus and implications on transcatheter aortic valve selection and sizing. Journal of the American College of Cardiology 2020; 75(11):1491.
J Am Coll Cardiol
Background ECG-gated computed tomography angiography (CTA) has become the standard for assessing the aortic root prior to transcatheter aortic valve replacement (TAVR). Current techniques rely primarily on systolic annular sizing for the selection and sizing of valve prostheses. We sought to evaluate the dynamic conformational changes of the LVOT compared to the aortic annulus, and determine whether LVOT morphology can have implications on prosthetic valve sizing and selection. Methods Preprocedural ECG-gated CTA data of 339 patients (aged 79 ±8.7 years, 52.6% male) who underwent TAVR were analyzed in this single-center retrospective study. The area of the aortic annulus and LVOT were measured by planimetry at 10% intervals throughout the cardiac cycle. Annular measurements were obtained inferior to the coronary cusps, and 10% of sub-annular calcifications were included in the calculated size. LVOT measurements were recorded 5mm inferior to the aortic annulus in a double oblique plane. Results In systole, the average annular size was 452.19 ± 19.52 mm2 compared to 455.74 ± 23.52 mm2 in the LVOT. In diastole, the average annular size was 420.98 ± 18.71 mm2 compared to 430 ± 25.42 mm2 in the LVOT. On average, the LVOT was 3.5mm2 (0.77%) larger in systole and 10mm2 (2.37%) larger in diastole compared to the annulus. Furthermore, a strong linear correlation was noted between the systolic and diastolic sizes of the annulus and LVOT, with a pooled value correlation coefficient (r) value of 0.72 and 0.73, respectively. Conclusion There is a statistically significant difference between the size of the aortic annulus and the LVOT in both systole and diastole. The difference is more pronounced in diastole. The data also shows a strong linear correlation between both the systolic and diastolic sizes of the annulus and the LVOT. The distal portion of the LVOT is within the TAVR valve landing zone but has frequently been neglected in the selection and sizing of valve prostheses. We have found that LVOT morphology varies throughout the cardiac cycle, especially diastole. Further study is required to identify whether distinct LVOT morphologies can be used to improve TAVR valve sizing and procedural outcomes.