Mitral Valve Replacement with the St. Jude Prosthesis
Abstract & Commentary
Synopsis: Long-term results with the St. Jude valve for isolated mitral valve disease confirm excellent biocompatibility and durability, but these results demonstrate the difficulty of long-term anticoagulation therapy.
Source: Remadi JP, et al. Circulation. 2001;103: 1542-1545.
Although the St. Jude prosthesis has become the standard for mechanical valve replacement, there is little long-term data on its use in the mitral position. Thus, Remadi and colleagues reported on a 10-19 year follow-up of 440 patients operated upon between 1979-1989 for isolated mitral valve replacement. Slightly more were women and their mean age was 60 years. Rheumatic heart disease was the etiology in 60% and the number with predominant stenosis or regurgitation was about the same. A majority had atrial fibrillation (57%). A 29 mm prosthesis was most commonly used (range, 25-33) and the subvalvular apparatus was not preserved. Only 5% of the surgeries were considered urgent. All patients were put on lifelong warfarin beginning on day 4. Follow-up was 98% complete at 19 years.
The results demonstrated a 4% perioperative mortality and a subsequent survival of 61% at 19 years. Survival free of valve-related complications was 84%. The most common nonvalvular cardiac cause of death was heart failure. The most common valve-related cause of death was sudden death, followed by hemorrhage. With regard to valve-related complications, no structural dysfunction was observed. Anticoagulation-related complications occurred at a frequency of 1% per patient-year. Thrombosis was much less common at 0.2% per patient-year. At 19 years, freedom from endocarditis was 99%, thrombus 97%, perivalvular leak 94%, valve avulsion 90%, re-operation 90%, thromboembolism 82%, and hemorrhage 80%. Of those patients undergoing reoperation, 12 had perivalvular leak, 2 thrombosis, and 1 endocarditis. Remadi et al concluded that long-term results with the St. Jude valve for isolated mitral valve disease confirm excellent biocompatibility and durability, but demonstrate the difficulty of long-term anticoagulation therapy.
Comment by Michael H. Crawford, MD
The St. Jude valve has become the most used prosthetic valve in the United States since Pfizer withdrew the Bjork-Shiley valve from the market. Consequently there is not much long-term data on this valve, especially in the mitral position. Therefore, these data from France are of interest. Although a small study by today’s mega-trial standards, it demonstrates excellent long-term results with this valve. No structural failure was documented and valve thrombosis was rare. Almost all of the reoperations were for perivalvular leak. The data related to the prosthesis are impressive and justify Remandi et al’s conclusions.
Most of the morbidity and one-quarter of the valve related deaths were related to anticoagulation problems. Despite more than 10 years of experience, poor anticoagulation control was demonstrated in 20% of the patients. Therefore, the major limitation to the use of this valve seems to be the need for anticoagulation. Some have suggested that if the patient is in sinus rhythm, the INR could be run at a lower level than the level of 3-4 used in this study. However, there are no data that this would reduce the number of anticoagulation-related problems and not result in more valve thrombosis. Also, many patients with mitral prostheses have atrial fibrillation and require anticoagulation for that reason.
The major cardiac nonvalvular cause of death was heart failure, which accounted for 38% of all deaths. This seems high in a group in which half had mitral stenosis. One potential reason for this finding was that chordal preservation was not used in these patients because they were all operated on in the 1980s before this had become common practice. Had chordal preservation techniques been used, heart failure related mortality may have been lower.