Aortic valve replacement with a stentless porcine bioprosthesis: multicentre trial. Canadian Investigators of the Toronto SPV Valve Trial.

Objective: To evaluate the clinical and hemodynamic performance of a new bioprosthesis for replacement of the aortic valve in humans.
Study Design: In a multicentre clinical trial between July 1991 and January 1994, 118 patients underwent aortic valve replacement with the Toronto SPV valve.
Results: Valvular pathology was aortic stenosis in 58%, insufficiency in 12% and mixed valvular disease in 30%; congenital bicuspid aortic valve was seen in 42% while heavy calcification was present in 86%. In approximately a third of the patients, concomitant coronary artery bypass surgery was performed. The mean period of aortic occlusion was 89 mins (range 48 to 180). Valve sizes implanted were: 22 mm (1%), 23 mm (7.6%), 25 mm (22.9%), 27 mm (37.3%) or 29 mm (31.4%). There were three deaths in the series: two from subacute bacterial endocarditis and one suicide. Early complications were cardiac arrest (0.8%), thromboembolism (2.5%) and arrhythmia (12.7%), while late complications were cardiac arrest (0.8%), arrhythmia (4.7%), angina (0.8%), thromboembolism (4.4%), endocarditis (1.7%) and other sepsis (0.8%). There were no valve related failures in 119 valve-years (mean follow-up 1.01 valve-year per patient). Follow-up echocardiography demonstrated an average decrease in mean systolic gradient of 36% from early to late postoperative period (P < 0.001) and an average increase in effective orifice area of 35% (P < 0.001) in the same period. No regurgitation was noted in 91% of patients at early, and 89% of patients at late, follow-up.
Conclusions: The Toronto SPV valve offers excellent hemodynamics, is relatively easy to insert and has few valve related complications. The observed changes in transvalvular area over time are consistent with a hypothesis that the ventricle undergoes remodelling following aortic valve replacement with this bioprosthesis. Longer follow-up is required to determine durability.