Comparison of dysfunction with mechanical and porcine mitral valve prostheses.

We reviewed the incidence of dysfunction of the Smeloff-Cutter mechanical prosthetic valve and the Hancock porcine prosthetic valve in the mitral position. The Smeloff-Cutter valve was implanted from 1966 to 1972; 107 patients were discharged from the hospital and were at risk for dysfunction. Follow-up averaged 10 +/- 0.7 years SD. The Hancock valve was implanted from 1971 through 1984; 473 patients were at risk and follow-up averaged 4.7 +/- 3.4 years SD. Dysfunction of the Smeloff-Cutter valve occurred as thrombosis with incomplete poppet opening in 13 patients. Dysfunction of the Hancock valve occurred as primary tissue failure in 47 patients. At 10 years the freedom from dysfunction of the Smeloff-Cutter valve was 84 +/- 5% SE and that for the Hancock valve was 71 +/- 4% SE (p greater than .06). The mortality associated with dysfunction of the Smeloff-Cutter valve was 46%; mortality associated with dysfunction of the Hancock valve was 15% (p less than .02). At 10 years the Hancock valve had a greater incidence of dysfunction than the Smeloff-Cutter valve but this difference was not statistically significant. The mortality associated with dysfunction of the Smeloff-Cutter valve, however, was three times that associated with dysfunction of the Hancock valve.