The effect of prosthesis-patient mismatch on aortic bioprosthetic valve hemodynamic performance and patient clinical status

BACKGROUND: High pressure gradients occurring through normally functioning prosthetic valves appear to be related to a mismatch between the effective orifice area of the prosthesis and the patient's body surface area. OBJECTIVE: To determine whether prosthesis-patient mismatch affects clinical and hemodynamic status, a group of patients with a bioprosthetic heart valve in the aortic position was prospectively evaluated at 6.2+/-4.4 years after implantation by transthoracic Doppler echocardiography. METHODS: Manufacturer-derived in vitro valve areas were available in 61 patients allowing classification into two subgroups, with or without mismatch, based on a valve area at implantation indexed for body surface area 0.85 cm2/m2 or less, or greater than 0.85 cm2/m2. Clinical and hemodynamic parameters evaluated at follow-up included New York Heart Association (NYHA) class distribution, mean transprosthetic gradient, prosthetic valve area and cardiac index. RESULTS: Prosthesis-patient mismatch was present in 32 of 61 patients (52%). Although NYHA class of the patients was similar in both groups, hemo-dynamic performance of the aortic bioprostheses was worse in patients with mismatch than in patients with no mismatch, as indicated by a higher mean gradient (22+/-9 versus 15+/-8 mm Hg, P=0.002) and a lower cardiac index (3.0+/-0.7 versus 3.4+/-0.7 L/min/m2, P=0.04). The prevalence and severity of intrinsic prosthetic dysfunction were similar in both groups. Despite similar NYHA functional class distribution in both groups, the occurrence of syncope, acute pulmonary edema and angina pectoris was significantly higher in patients with mismatch (50% versus 21%, P=0.017). CONCLUSIONS: Prosthesis-patient mismatch is associated with worse hemodynamic performance and higher prevalence of adverse clinical events. However, mismatch did not promote accelerated hemodynamic or structural deterioration of the bioprosthesis.