A single center experience with the freestyle bioprosthesis: midterm results at the Québec Heart Institute

Stentless bioprostheses show excellent early hemodynamic performance. However, longevity still remains unknown. This study reports midterm follow-up in 419 patients in which a Freestyle bioprosthesis (Medtronic Heart Valves, Minneapolis, MN) was inserted between January 1993 and January 2000 at the Quebec Heart Institute (Ste-Foy, Québec, Canada). Mean age at implantation was 68.0 +/- 8.2 years. Implantation was subcoronary in 81.9% of the patients, as a root replacement in 16.5%, and as a root inclusion in 1.7%. Mortality at 30 days was 6.2% for the whole cohort (2.8% for isolated subcoronary aortic valve replacement). Female gender, root implantation, valve sizes 19 to 21 mm, previous surgery, a history of stroke and diabetes were identified as predictors of 30-day mortality. Actuarial freedom from all death causes was 81.5% at 7 years; freedom from valve-related deaths 97.0%, and freedom from cardiac deaths 92.7%. Freedom from thromboembolic events was 86.1% at 7 years (55.1% of events were < 30 days). Freedom from endocarditis and hemorrhagic complications were respectively 98.5% and 95.6% at 7 years. Six patients required reoperations for valve explantation: 2 for endocarditis, 2 for structural dysfunction, and 2 for nonstructural dysfunction. Incidence of moderate or severe valve insufficiency at annual echocardiographic follow-up was: discharge: 0.6%; year 1: 0.7%; year 2: 1.3%; year 3: 3.3%; year 4: 3.7%; year 5: 2.6%; year 6: 0%. At 6 years after implantation, mean transvalvular gradient and effective valve orifice area were comparable to the year 1 values. This single center experience with the Medtronic Freestyle prosthesis shows preserved hemodynamic performance and low valve-related complications at midterm.