Embolism, thrombosis and anticoagulant haemorrhage in mitral valve disease. A prospective study of patients having valve replacement with the pericardial xenograft.

The incidence of systemic embolism has been assessed in 461 patients having mitral valve replacement with the pericardial xenograft. No patient received long-term anticoagulant therapy. The bulk of the patients received six weeks' postoperative treatment with warfarin (322 patients) or dipyridamole (71 patients). No case of valve thrombosis has been encountered. Embolism was recognised in 9 patients of whom 7 had chronic atrial arrhythmias. No patient has died from the effects of embolism and only 2 patients have any residual clinical deficit. The majority of the episodes occurred within the first 6 postoperative weeks. The linearised rate of embolism is 0.55% per annum and is very similar to the rates reported after closed mitral valvotomy, open mitral commissurotomy and mitral valve repair. This rate of embolism is significantly lower than that reported after mitral valve replacement with porcine heterografts (2.9-5.3% per annum) even in patients having long-term anticoagulation where there is an additional haemorrhagic risk associated with the anticoagulant treatment.