THE EFFECT OF PROSTHESIS-PATIENT MISMATCH ON AORTIC BIOPROSTHETIC VALVE HEMODYNAMIC PERFORMANCE AND PATIENT CLINICAL STATUS

BACKGROUND: High pressure gradients occurring through normally functio ning prosthetic valves appear to be related to a mismatch between the effective orifice area of the prosthesis and the patient's body surfac e area. OBJECTIVE: To determine whether prosthesis-patient mismatch af fects clinical and hemodynamic status, a group of patients with a biop rosthetic heart valve in the aortic position was prospectively evaluat ed at 6.2+/-4.4 years at implantation by transthoracic Doppler echocar diography. METHODS: Manufacturer-derived in vitro valve areas were ava ilable in 61 patients allowing classification into two subgroups, with or without mismatch, based on a valve area at implantation indexed fr o body surface area 0.85 cm(2)/m(2) or less, or greater than 0.85 cm(2 )/m(2). Clinical and hemodynamic parameters evaluated at follow-up inc luded New York Heart Association (NYHA) class distribution, mean trans prosthetic gradient, prosthetic valve area and cardiac index. RESULTS: Prosthesis-patient mismatch was present in 32 of 61 patients (52%). A lthough NYHA class of the patients was similar in both groups, hemodyn amic performance of the aortic bioprostheses was worse in patients wit h mismatch than in patients with no mismatch, as indicated by a higher mean gradient (22+/-9 versus 15+/-8 mmHg, P=0.002) and a lower cardia c index (3.0+/-0.7 versus 3.4+/-0.7 L/min/m(2), P=0.04). The prevalenc e and severity of intrinsic prosthetic dysfunction were similar in bot h groups. Despite similar NYHA functional class distribution in both g roups, the occurrence of syncope, acute pulmonary edema and angina pec toris was significantly higher in patients with mismatch (50% versus 2 1%, P=0.017). CONCLUSIONS: Prosthesis-patient mismatch is associated w ith worse hemodynamic performance and higher prevalence of adverse cli nical events. However, mismatch did not promote accelerated hemodynami c or structural deterioration of the bioprosthesis.