Prosthesis size and long-term survival after aortic valve replacement

Objective: This study was undertaken to quantify the relationship between prosthesis size adjusted for patient size (prosthesis-patient size) and long-term survival after aortic valve replacement. Methods: Data from nine representative sources on 13,258 aortic valve replacements provided 69,780 patient-years of follow-up (mean 5.3 +/- 4.7 years), with reliable survival estimates to 15 years. Prostheses included 5757 stented porcine xenografts, 3 198 stented bovine pericardial xenografts, 3583 mechanical valves, and 720 allografts. Manufacturers' labeled prosthesis size was 19 rum or smaller in 1109 patients. Expressions of prosthesis-patient size assessed were indexed internal prosthesis orifice area (in centimeters squared per square meter of body surface area) and standardized internal prosthesis orifice size (Z, the number of SDs from mean normal native aortic valve size). Multivariable hazard domain analysis with balancing score and risk factor adjustment quantified the association of prosthesis-patient size with survival. Results: Prosthesis-patient size down to at least 1.1 cm(2)/m(2) or -3 Z did not adversely affect intermediate- or long-term survival (P > 2). However, 30-day mortality increased 1% to 2% when indexed orifice area fell below 1.2 cm(2)/m(2) (p =.002) or standardized orifice size fell below -2.5 Z (P =.0003). The increased early risk affected fewer than 1% of patients receiving bioprostheses but about 25% of those receiving mechanical devices. Conclusions: Aortic prosthesis-patient size down to 1.1 cm(2)/m(2) or -3 Z did not reduce intermediate- or long-term survival after aortic valve replacement. However, patient-prosthesis size under 1.2 cm(2)/m(2) or - 2.5 Z was associated with a 1% to 2% increase in 30-day mortality. Prosthesis-patient sizes this small or smaller were rarely implanted in patients receiving bioprostheses.