Background
Patient-prosthesis mismatch (PPM) is present when the effective orifice area (EOA) of the inserted prosthetic valve is too small in relation to body size, which results in an increased postoperative transvalvular gradient. This study was conducted to determine the incidence and identify the risk factors associated with this phenomenon.
Patients and methods
In total, 46 patients undergoing cardiac surgery for mechanical mitral valve replacement were enrolled. The EOA of the prostheses was estimated by the continuity equation (CE), pressure half-time, and reference values to determine the incidence of the mismatch, then the EOA was estimated by the CE only to determine the risk factors of the mismatch. The mismatch was defined as an indexed EOA less than or equal to 1.2 cm/m. The mean clinical and echocardiographic follow-up was 6 months postoperatively.
Results
The incidence of mitral PPM ranged from 15% in pressure half-time method (seven patients) to 26% in the referred EOA method (12 patients) to 54% in CE method (25 patients). PPM was identified in patients with preoperative rheumatic mitral valve pathology (=0.043), higher preoperative New York Heart Association class (=0.016), preoperative atrial fibrillation (=0.048), mitral valve stenosis (=0.020), and smaller left ventricular dimensions.
Conclusions
PPM in mitral position is a fact and its incidence is variable according to the different methods of determining EOA of the prosthetic valve.