Long-term clinical results after mitral valve replacement with the Björk-Shiley prosthesis
Lindblom, D.
Journal of Thoracic and Cardiovascular Surgery 95(2): 321-333
1988
ISSN/ISBN: 0022-5223 PMID: 3339899 Document Number: 319027
The experience of 810 mitral valve replacements performed during a 15-year period (1969 to June 1983) is reported. All but one patient received a Bjork-Shiley disc value. Five different Bjork-Shiley models were used (Delrin, n = 51; standard pyrolytic carbon, n = 307; convexo-concave with an opening angle of 60 degrees, n = 229; convexo-concave with an opening angle of 70 degrees, n = 123; and the Monostrut value, n = 99). The follow-up was 99.8% complete and covered 4614 patient-years (mean 6.0 years). An autopsy was performed in 77% of all fatalities. Early mortality was 5.7% and decreased during the study period. The 5-, 10-, and 15-year actuarial survival rates (early mortality excluded) were 78%, 62% and 51%, respectively, and the complication-free survival rates at the same time intervals were 67%, 51%, and 36%. Seven percent of early deaths and 25% of late deaths were valve related, and most of these were due to valve thrombosis. The incidence of valve thrombosis was significantly (p < 0.0005) reduced after the introduction of the convexo-concave valves, and this reduction was achieved without any increase in bleeding complications. The only patient-related factor found to be related to postoperative thromboembolism was a history of preoperative embolism (p < 0.05). Most events occurring after implant (death, embolism, valve thrombosis, reoperation, and valve failure) had a peak incidence during the first postoperative year, whereas anticoagulant-related bleedings occurred at a constant rate of 1.2/100 patient-years. The linearized incidence of embolism was 1.6/100 patient-years (actuarial incidence at 5 and 10 years 6.9% and 13.0%, respectively). Seven strut fractures occurred (0.2/100 patient-years, actuarial incidence at 5 and 10 years 1.1%), as did five instances of prosthetic valve endocarditis (0.1/100 patient-years, actuarial incidence at 5 and 10 years, 0.7% and 1.3%). A new concept of valve failure is presented and includes a distinction between events related to the surgical procedure (treatment failure; 1.9/100 patient-years, actuarial incidence at 5 and 10 years 11.0% and 13.5%) and events possibly related to the prosthesis (prosthetic failure; 1.1/100 patient-years, actuarial incidence at 5 and 10 years 7.0 % and 8.0%).