Prosthesis-patient mismatch after aortic valve replacement: Impact of age and body size on late survival

Background. The purpose of this study was to identify patient subgroups in which prosthesis-patient mismatch most influenced late survival. Methods. Over a 12-year period, 1,400 consecutive patients underwent bioprosthetic (933 patients) or mechanical (467) aortic valve replacement. Prosthesis-patient mismatch was defined as prosthetic effective orifice area/body surface area less than 0.75 cm²/m² and was present with 11% mechanical and 51% bioprosthetic valves. Results. With bioprosthetic valves, prosthesis-patient mismatch was associated with impaired survival for patients less than 60 years old (10-year: 68% ± 7% mismatch versus 75% ± 7% no mismatch, p< 0.02) but not older patients (p= 0.47). Similarly, with mechanical valves, prosthesis-patient mismatch was associated with impaired survival for patients less than 60 years old (10-year: 62% ± 11% versus 79% ± 4%, p < 0.005) but not older patients (p = 0.26). For small patients (body surface area less than 1.7 m²), prosthesis-patient mismatch did not impact survival with bioprosthetic (p = 0.32) or mechanical (p= 0.71) valves. For average-size patients (body surface area 1.7 to 2.1 m²), prosthesis-patient mismatch was associated with impaired survival with both bioprosthetic (p < 0.05) and mechanical (p< 0.005) valves. For large patients (body surface area greater than 2.1 m²), prosthesis-patient mismatch was associated with impaired survival with mechanical (p< 0.04) but not bioprosthetic (p= 0.40) valves. Conclusions. Prosthesis-patient mismatch had a negative impact on survival for young patients, but its impact on older patients was minimal. In addition, although prosthesis-patient mismatch was not important in small patients, prosthesis-patient mismatch negatively impacted survival for average-size patients and for large patients with mechanical valves.