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Mitral Valve Repair Durability
Abstract & Commentary
Synopsis: The durability of mitral valve repair is not constant, and the progressive incidence of more than trivial regurgitation needs to be considered in selecting a strategy for treating chronic mitral regurgitation.
Source: Flameng W, et al. Circulation. 2003;107: 1609-1613.
Mitral valve repair for severe nonrheumatic regurgitation is highly successful with regard to survival and freedom from reoperation for up to 10 years, but the recurrence of significant mitral regurgitation is not known. Thus, Flameng and colleagues from Leuven, Belgium, reviewed their experience with mitral valve repair done by a surgeon in 242 consecutive patients. Two-thirds of the patients had posterior leaflet prolapse and ruptured chordae. Mean EF was 66%, and average PA pressure was 40/16 mm Hg. Three-fourths were in sinus rhythm, and 85% were class II-III. Clinical and echocardiographic follow-up were performed at 1 month and every 6 months thereafter. At 8 years postrepair, clinical outcome was excellent, survival was 91%, and freedom from reoperation was 94%. However, freedom from nontrivial mitral regurgitation (> 1 ± 4) was 94% at 1 month, 59% at 5 years, and 71% at 7 years. The recurrence rate of > 1+ regurgitation was 8% per year, and 3-4+ regurgitation was 4% per year. The surgical procedure employed could only partially explain the recurrence of regurgitation. Flameng et al concluded that the durability of mitral valve repair is not constant, and the progressive incidence of more than trivial regurgitation needs to be considered in selecting a strategy for treating chronic mitral regurgitation.
Comment by Michael H. Crawford, MD
This is the first echocardiographic study to evaluate long-term freedom from mitral regurgitation following mitral valve repair. As such, it is limited because of its retrospective design and the fact that the posthospital echocardiograms were done by the individual referring cardiologists, rather than by 1 laboratory where reader consistently could be better controlled. This is an issue since there are no universally agreed upon or applied criteria for grading the severity of mitral regurgitation. Most labs use a semiquantitative visual approach, but some try to quantitate regurgitation using PISA and other methods. Previous data have suggested that the visual distribution between trivial, mild, and mild-to-moderate mitral regurgitation is probably unrealistic. However, moderate-to-severe can usually be distinguished from lower grades. Thus, the moderate-to-severe (3 to 4+) regurgitation evaluated in this study is probably meaningful, but the > 1+ or > trivial data are suspect.
Despite these limitations, the study makes 2 cogent points. First, the incidence of moderate-to-severe mitral regurgitation is not inconsequential at 7 years (29%), but freedom from reoperation at 8 years was 94%.
Other studies have shown 10-year reoperative rates of 4-7%, and 20-year rates of 20%. These results are clearly better than those observed with tissue prosthetic valves, where reoperation rates can approach 30% at 10 years, but inferior to mechanical prosthetic valves. Given that only one-third of their patients were on anticoagulants (mainly due to atrial fibrillation), these results are excellent.
Second, the constant rate of recurrence of valve regurgitation during long-term follow-up in this study suggests that the basic valvular degeneration that caused the regurgitation in the first place continues. Advanced myxomatous changes and prolapse of both leaflets increase the rate of subsequent valve failure. Other studies have shown that surgical issues dominate the recurrence of regurgitation in the first year, but that the underlying disease determines the long-term success. This study confirmed that certain surgical issues can explain some of the cases of recurrent regurgitation. The use of an annuloplasty ring, valve resection, and transposition or the use of artificial chordae, rather than chordal shortening, decreases the incidence of recurrent regurgitation.
Flameng et al’s admonition that their data should be considered when discussing treatment options with the patient is well taken. Their data increase our knowledge of the unnatural history (postsurgical) of chronic degenerative mitral valve disease but unfortunately make decisions regarding treatment more difficult. For example, the fact that one-third of their patients were on anticoagulation postoperatively, mainly for atrial fibrillation, makes one wonder about the initial decision to repair, rather than replace. The management of severe mitral regurgitation continues to be difficult.
Dr. Crawford if Professor of Medicine, Mayo Medical School; Consultant in Cardiovascular Diseases, and Director of Research, Mayo Clinic, Scottsdale, AZ.