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 I 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.

Nyckelord

aortic bioprosthesis

stentless

long term follow up

relative survival rate

hemodynamic evaluation

echocardiography

valve replacement

doppler ultrasound

stenosis

hypertrophy

regression

exercise

area

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