Bileaflet mechanical prostheses in mitral and multiple valve replacement surgery: influence of anticoagulant management on performance.
BACKGROUND
The St. Jude Medical (SJM) mechanical prosthesis has been the predominant mechanical prosthesis worldwide since its introduction in 1977. The CarboMedics (CM) mechanical prosthesis, also a bileaflet pyrolite carbon prosthesis, was introduced in 1986 and was approved by the Food and Drug Administration of the United States in 1993. The experience of the two prostheses was evaluated in a parallel, nonrandomized study commencing with the CM investigational study in 1989.


RESULTS
The clinical performance of the two prostheses was evaluated in accordance with the Guidelines for Reporting Morbidity and Mortality After Cardiac Valvular Operations. The CM prosthesis was implanted in 239 mitral valve replacements (MVR) and 106 multiple valve replacements (MR), and the SJM prosthesis was implanted in 379 MVR and 137 MR. The CM and SJM populations were not distinguished within MVR and MR for mean age, previous surgery, concomitant surgery, mean follow-up, and late mortality (P=NS). The linearized occurrence rate for the combined experience for major thromboembolic and hemorrhage events >30 days was 3.4% of patients per year for MVR (inclusive of cerebral thromboembolism reversible, major; systemic; thrombosis; and fatal; and major systemic hemorrhage) and for MR was 3.9% of patients per year (P=NS between prostheses by position). The major crude event rate for < or =30 days was 1.3% for MVR and 1.2% for MR (P=NS between prostheses by position). The inadequacy of anticoagulation (as determined by international normalized ratio 2.5) for all thromboembolic events (major and minor) < or =30 days was 93%, and that for >30 days was 75%. The freedom from major thromboembolism for MVR at 3 years was 92.7+/-1.9% for CM and 94.0+/-1.5% for SJM; for MR, it was 94.2+/-3.0% for CM and 93.5+/-2.5% for SJM (P=NS). The freedom from major thromboembolism exclusive of early events for MVR at 3 years was 94.4+/-1.8% for CM and 94.8+/-1.4% for SJM, and for MR, it was 94.2+/-3.0% for CM and 95.0+/-2.2% for SJM (P=NS). The freedom from major thromboembolism and hemorrhage for prostheses (CM and SJM) by valve positions (MVR and MR) was also indistinguishable (P=NS).


CONCLUSIONS
There are no distinguishing performance characteristics with regard to thromboembolic and hemorrhagic events between the CM and the SJM mechanical prostheses in MVR and MR. There was an identified need for improvement in the early and late anticoagulant management. A randomized trial with optimization of anticoagulant management between the CM and SJM mechanical prostheses is recommended.
Jamieson
W R
WR
St Paul's Hospital-Heart Centre, Vancouver Hospital and Health Sciences Centre, University of British Columbia, Canada.
Miyagishima
R T
RT
Tyers
G F
GF
Lichenstein
S V
SV
Munro
A I
AI
Burr
L H
LH
D000925:Anticoagulants / Q000627:therapeutic use*; D016063:Blood Loss, Surgical / Q000517:prevention & control; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D008875:Middle Aged; D008943:Mitral Valve / Q000601:surgery*; D013923:Thromboembolism / Q000517:prevention & control
D000925:Anticoagulants