Eleven years' experience with the Biocor stentless aortic bioprosthesis: clinical and hemodynamic follow-up with long-term relative survival rate.

OBJECTIVE: The long-term durability and hemodynamics of stentless valves are largely unknown. Our aim was to prospectively investigate long-term hemodynamic function and clinical outcome after aortic valve replacement with the Biocor stentless aortic bioprosthesis.

PATIENTS AND METHODS: Between October 1990 and November 2000 we inserted the Biocor stentless aortic valve in 112 patients (male/female: 38:74) with a mean age of 78.5 years (median 79.3, range 60-88). The predominant diagnosis was aortic stenosis in 86% of the patients. Concomitant coronary artery bypass surgery was performed in 31% of the patients. Average prosthetic valve size was 23.3+/-1.6 mm. All patients were followed in a prospective study with a mean follow-up of 66+/-33 months. The follow-up was 100% complete with a closing interval from October 1 to December 31, 2001. The observed actuarial survival of patients was compared to expected survival for an age- and gender-matched comparison population as calculated from Swedish life tables by Statistics Sweden. Relative survival rates were calculated annually for the patient population.

RESULTS: Early mortality was 7% (8/112). Late mortality was 38% (43/112). Actuarial survival at 5 and 9 years was 74+/-5% and 38+/-7%, respectively. Observed survival among patients was not different from the expected survival for the comparison population and calculation of relative survival rates indicates a 'normalized' survival pattern for the patient population. At 5 and 9 years the actuarial freedom from valve-related death was 94+/-3% and 86+/-6%; from cardiac death, 82+/-4% and 57+/-8%; from valve reoperation, 96+/-2% and 87+/-6%; from structural valve degeneration, 96+/-2% and 87+/-6%; from thromboembolism, 89+/-4% and 71+/-9%; and from endocarditis, 96+/-2% and 90+/-5%. At 9 years the transvalvular mean pressure difference for all valves was 7.3+/-1.3 mmHg (range 6-10 mmHg) measured with Doppler echocardiography. Aortic regurgitation progressed slowly over time in a few patients and necessitated reoperation in two patients.

CONCLUSION: The Biocor stentless bioprosthesis has an excellent hemodynamic function and confers a good long-term outcome. This patient population could be regarded as 'cured' from valve disease since the observed survival did not differ from the expected survival for an age- and gender-matched Swedish comparison population, a conclusion that is also supported by a constant relative survival after the first postoperative year. However, despite excellent long-term hemodynamics, patients with stentless bioprostheses need to be evaluated with echocardiography at regular intervals to discover the rare cases of progressive aortic regurgitation.