Objective : To identify factors affecting survival and left ventricular mass regression after aortic valve replacement with stented and stentless bioprostheses.
Methods : In a retrospective study 145 patients with a Toronto stentless prosthesis are compared to 110 patients with a stented Carpentier-Edwards valve. In-hospital mortality and 5 to 10-years outcome as well as transprosthetic gradients and left ventricular mass regression are analyzed in view of patient-prosthesis mismatch, defined as an indexed effective orifice area </= 0,85 cm²/m².
Results : Actuarial survival is 82 % at 5 years after stentless AVR versus 68 % after stented AVR (p<0,001) in elderly patients, aging respectively 75,5 ± 7,4 years and 76,3 ± 5,9 years. Patient-prosthesis mismatch was found in 18 % after stentless AVR versus 41 % after stented AVR (p < 0,0001). Univariate analysis revealed that advanced age at the time of operation, NYHA class 4, implantation of a stented xenograft, presence of PPM and severe preoperative LV hypertrophy (LVMI > 150 g/m²) affected survival adversely. In multivariate analysis, only age, NYHA class 4 and high-grade LV hypertrophy remained a risk factor.
Stented and stentless AVR were equally effective in terms of transprosthetic gradients and left ventricular mass regression. LVMI showed a rapid decrease during the first year but tended to increase beyond the third year after AVR, independently of the prosthesis type and the presence of PPM. Arterial hypertension was defined as the major determinant of this phenomenon (correlation factor 0,55 (p<0,05)).
Conclusion : In comparison with stented xenografts, the use of a stentless prosthesis decreases significantly the risk of patient-prosthesis mismatch and results in a midterm survival advantage after AVR. However, this benefit is not expressed by a continuous improving left ventricular mass regression, indicating that this variable might be more dependent on non-valve related factors such as arterial hypertension.