Three dimensional evaluation of the aortic annulus using multislice computer tomography: are manufacturer's guidelines for sizing for percutaneous aortic valve replacement helpful?

Aims To evaluate the effects of applying current sizing guidelines to different multislice computer tomography (MSCT) aortic annulus measurements on Corevalve (CRS) size selection. Methods and results Multislice computer tomography annulus diameters [minimum: D-min; maximum: D-max; mean: D-mean = (D-min + D-max)/2; mean from circumference: D-circ; mean from surface area: D-CSA] were measured in 75 patients referred for percutaneous valve replacement. Fifty patients subsequently received a CRS (26 mm: n = 22; 29 mm: n = 28). Dmin and D-max differed substantially [mean difference (95% CI) = 6.5 mm (5.7-7.2), P < 0.001]. If D-min were used for sizing 26% of 75 patients would be ineligible (annulus too small in 23%, too large in 3%), 48% would receive a 26 mm and 12% a 29 mm CRS. If D-max were used, 39% would be ineligible (all annuli too large), 4% would receive a 26 mm, and 52% a 29 mm CRS. Using D-mean, D-circ, or D-CSA most patients would receive a 29 mm CRS and 11, 16, and 9% would be ineligible. In 50 patients who received a CRS operator choice corresponded best with sizing based on DcsA and D mean (76%, 74%), but undersizing occurred in 20 and 22% of which half were ineligible (annulus too large). Conclusion Eligibility varied substantially depending on the sizing criterion. In clinical practice both under- and oversizing were common. Industry guidelines should recognize the oval shape of the aortic annulus.