Mechanical versus biological valve prosthesis in the mitral position: a 10-year follow up of St. Jude Medical and Biocor valves.

BACKGROUND AND AIM OF THE STUDY

During the past 30 years, the development of mechanical and biological valves has led to major improvements in patient survival. Here, we present long-term results obtained with both types of prosthesis.

METHODS

At our institution, between 1985 and 1989, 158 patients received a Biocor porcine bioprosthesis, and 100 patients a St. Jude Medical (SJM) mechanical valve. Preoperatively, mean age, male:female ratio, NYHA functional class and pathology of mitral valve disease were similar in both groups.

RESULTS

The 30-day mortality was 4.4% in the Biocor group and 4% in the SJM group, the major cause being congestive heart failure. Late mortality was 17.9% and 15.6% respectively in the two groups, but valve-related mortality was very low in both (1.3% versus 4.2%). Ten-year survival was similar in each group (77.8+/-3.4% versus 81.0+/-3.9%; p = 0.538). Ten-year freedom from anticoagulant-related hemorrhage was higher with Biocor prostheses (99.3+/-0.7% versus 90.9+/-3.1%; p = 0.007). Valve thrombosis was seen only in the SJM group, and structural valve degeneration (SVD) only in the Biocor group. Ten-year freedom from reoperation was lower in the Biocor group (84.9+/-3.2% versus 92.2+/-2.8%; p = 0.206). The significant causes of reoperation were SVD in the Biocor group and valve thrombosis in the SJM group. Freedom from prosthetic valve endocarditis was similar in both groups (96.3+/-1.6% versus 95.5+/-2.2%).

CONCLUSION

As no difference was seen in survival and reoperation rates between patients receiving either bioprostheses or mechanical valves, the valve used will depend on the surgeon's choice and the type of patient, notably elderly patients who are intolerant of anticoagulation, and young women wishing to have children.