Poor clinical performance of the Wessex porcine heart valve bioprosthesis at nine years' follow up

Abstract

Objective: To assess the long term performance of the Wessex porcine bioprostheses implanted in a consecutive series of patients.

Design: A retrospective case series.

Patients: Between January 1985 and July 1991, 184 Wessex bioprostheses (78 mitral, 102 aortic, and 4 tricuspid) were implanted in 150 patients. The patients were 55% (83/150) male and 45% (67/150) female; mean age was 60 (SD 10) years.

Results: Hospital mortality was 9.3% (14/150). Total follow up was 696 patient-years (mean 4.7 years per patient). Linearised rates (events per 100 patient-years (SEM) for postoperative complications for patients with isolated mitral valve replacement, isolated aortic valve replacement, and multiple valve replacement were, respectively: late mortality: 4.7 (1.6), 3.3 (0.9), and 4.9 (1.9); thromboembolism: 5.8 (1.8), 3.0 (0.9), and 2.8 (1.4); valve thrombosis: 1.0 (0.7), 0.3 (0.3), and 0.7 (0.7); structural failure: 5.8 (1.7), 1.9 (0.7), and 7.1 (2.2). Actuarial freedom from complications at nine years (70% confidence interval) was: late mortality: 61 (9)%, 57 (13)%, and 59 (12)%; thromboembolism and valve thrombosis: 71 (9)%, 79 (6)%, and 81 (8)%; structural failure: 33 (14)%, 50 (16)%, and 12 (14)%; all valve related morbidity/mortality: 31 (10)%, 21 (11)%, and 7 (9)%. Stent fractures appeared in 11 of 17 explanted prostheses; actuarial freedom from stent fracture at nine years was 66 (12)%.

Conclusions: The Wessex bioprosthesis is associated with high thrombogenicity, early structural dysfunction, and a high valve related morbidity/mortality which justifies very close follow up of patients fitted with them.