Preoperative echocardiographic prediction of small prosthesis size for aortic valve replacement

Prosthesis size is known to have an effect on long term outcome after heart valve replacement. We evaluated 115 patients subjected to aortic valve replacement to assess the ability by preoperative echocardiography to identify patients having small aortic roots and thereby likely to receive a small prosthesis (size 19 or 21), previously shown to be associated with a worse prognosis.

From an initial part of the study (Group A), comprising 67 patients, we evaluated the influence of image quality on the accuracy for prediction of patients receiving a small prosthesis. In a second series of 48 patients (Group B), we tested the predictive value of various limits of aortic annulus diameter to define patients at risk of receiving a small prosthesis.

The measurement of aortic annulus diameter in Group A gave a reasonable correlation to subsequent prosthetic dimension (r = 0.73, n = 59). However, there was a considerable variation of echocardiographic aortic annulus diameter among patients receiving prostheses of the same size. In Group B, an aortic annulus diameter of < or = 22 mm correctly identified 10 of 13 patients receiving a small prosthesis (sensitivity 77%). Twenty-two of 25 patients (88%) with an aortic annulus diameter > 22 mm received a large prosthesis.

We conclude that the echocardiographic measurement of the aortic annulus diameter is a fairly sensitive method to identify patients receiving a small prosthesis. However, the predictive accuracy is dependent upon training as well as image quality. Furthermore, the value of planning in advance the type of prosthesis, annuloplasty or homograft for aortic valve replacement remains to be shown.