Prosthesis-patient mismatch after transcatheter aortic valve implantation using the Edwards SAPIEN™ prosthesis

Prosthesis-patient mismatch (PPM) is defined as a too small effective orifice area (EOA) of the prosthetic valve in relation to the patient's body size and has been documented to be related to adverse outcomes after conventional aortic valve replacement (AVR). Aim of this study was to analyze the incidence of PPM after transcatheter aortic valve implantation (T-AVI) using the Edwards SAPIEN prosthesis and its relation to postoperative outcome.

200 consecutive high-risk patients underwent transapical aortic valve implantation (TA-AVI) between February 2006 and January 2009 and fulfilled 1 year follow-up were included. Severe PPM was defined as indexed EOA (EOAi) <0.65 cm2/m2 and moderate PPM as EOAi = 0.65-0.85 cm2/m2, EOA was calculated from transthoracic echocardiographic (TTE) measurements using the continuity equation. Total 112 patients with sufficient postoperative TTE image quality formed the study group.

EOAi increased from 0.3 ± 0.1 cm2/m2 (preoperatively) to 1.1 ± 0.4 cm2/m2 after TA-AVI (p < 0.001). According to the standard definitions, PPM was seen in 38.4% of the patients and 9.8% presented with severe PPM. The occurrence of PPM had neither an effect on clinical outcome in terms of NYHA class nor on survival. Patients with PPM had significantly higher postoperative transprosthetic gradients (mean gradient 10.4 ± 4.1 versus 7.1 ± 3.0 mm Hg, p < 0.001). Based on the in vitro EOA data obtained from pulse duplicator measurements, however, none of the patients was judged to have PPM.

Transcatheter AVI provides good antegrade hemodynamic function and EOAi improves significantly. According to standardized evaluations PPM occurs after TA-AVI, but it is not associated with adverse outcomes. Thus use of the continuity equation may not adequately reflect the situation after T-AVI or the current definition of PPM is not suitable for T-AVI prostheses.