Interact CardioVasc Thorac Surg 2008;7:477-484. doi:10.1510/icvts.2007.174243
© 2008 European Association of Cardio-Thoracic Surgery
Best evidence topic - Valves |
Is a flexible mitral annuloplasty ring superior to a semi-rigid or rigid ring in terms of improvement in symptoms and survival?
Tjian Cheea,
Ross Hastona,
Athena Togoa and
Shahzad G. Rajab,*
a Department of Cardiothoracic Surgery, Western Infirmary, Glasgow, UK
b Department of Cardiothoracic Surgery, Harefield Hospital, Hill End Road, Harefield, UB9 6JH, Middlesex, UK
Received 21 December 2007;
received in revised form 14 February 2008;
accepted 15 February 2008
*Corresponding author. Tel.: +44 1895 828665; fax: +44 1895 828666.
E-mail address: drrajashahzad{at}hotmail.com (S.G. Raja).
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Abstract
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A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether, in patients with mitral regurgitation secondary to degenerative mitral valve disease requiring mitral valve repair with an annuloplasty ring, a flexible ring is superior to a semi-rigid or rigid ring in terms of improvement in symptoms and survival. Using the reported search 478 papers were identified. Twelve papers of which seven were echocardiographic studies and five clinical studies, including two randomised controlled trials (RCTs), represented the best evidence on the subject. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study comments and weaknesses were tabulated for these. We conclude that current best available evidence suggests that, in patients with a flexible annuloplasty ring compared to patients with a semi-rigid/rigid annuloplasty ring, the improvement in LV systolic function as reported by all the seven sophisticated echocardiographic studies with a total of 266 patients does not translate into better clinical outcomes as five clinical studies with a total of 941 patients, including two RCTs, report comparable clinical outcomes for patients with mitral regurgitation secondary to degenerative mitral valve disease requiring mitral valve repair with an annuloplasty ring.
Key Words: Mitral valve; Mitral valve insufficiency; Annuloplasty ring; Survival; Evidence-based medicine
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1. Introduction
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A best evidence topic was constructed according to a structured protocol. This protocol is fully described in the ICVTS [1].
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2. Clinical scenario
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Your consultant is about to operate on a 48-year-old patient with moderate to severe mitral regurgitation (MR) due to degenerative disease of the mitral valve. The scrub nurse asks you about the type of ring that your boss is going to use. You say that he always uses a flexible ring. She asks you why and your boss overhears your rather unconvincing response and suggests that you go and look up the evidence rather than cannulating today.
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3. Three-part question
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In [patients with mitral regurgitation secondary to degenerative mitral valve disease requiring a mitral valve repair with an annuloplasty ring] is a [flexible ring superior to a semi-rigid or rigid ring] in terms of [improvement in symptoms and survival]?
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4. Search strategy
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The English language scientific literature was reviewed primarily by searching Medline from 1950 through January 2008 using Ovid interface.
[Mitral valve repair.mp OR mitral valve reconstruction.mp OR mitral valvuloplasty.mp] AND [Annuloplast$.mp OR valvuloplast$.mp] AND [Exp survival OR exp outcome OR outcome$.mp].
The ‘related articles’ function was used to broaden the search and all abstracts, studies, and citations scanned were reviewed. The reference lists of articles found through these searches were also reviewed for relevant articles. Only studies recruiting patients with MR secondary to degenerative mitral disease were included.
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5. Search outcome
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A total of 478 papers were found using the search strategy. Twelve papers were deemed to represent the best evidence on the topic and are summarised in Table 1.
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6. Discussion
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Several sophisticated echocardiographic studies have demonstrated that patients with a flexible annuloplasty ring have better LV systolic function than patients with a rigid annuloplasty ring after mitral valve reconstruction for chronic MR secondary to degenerative disease of the mitral valve [2–8].
Borghetti et al. [2] in their retrospective study of 44 patients showed that autologous pericardium seems to be superior to rigid prosthetic rings for annuloplasty in MV repair, since it provides more favourable mitral annulus dynamics and preserves LV function during stress conditions.
Dall'Agata et al. [3] in a small study of 19 patients showed that the Cosgrove-Edwards ring (n=15) maintains its flexibility early after implantation and demonstrates significant systolic–diastolic changes in the mitral orifice area during the cardiac cycle compared to Carpentier rigid ring (n=4). Similar findings have been reported by other authors [4–8].
Interestingly, clinical studies [9–13] comparing outcomes of patients who underwent mitral valvuloplasty for degenerative MR with either a semi-rigid/rigid ring or flexible ring have shown comparable outcomes contrary to the findings of the echocardiographic studies.
Chung et al. [9] in a recently published study compared the long-term clinical and echocardiographic outcomes of 294 patients who underwent mitral valvuloplasty for degenerative mitral regurgitation (MR) with either a Carpentier-Edwards (semi-rigid) ring (n=153) or a Duran (flexible) ring (n=141) between 1994 and 2004. Their results showed comparable long-term outcomes in terms of LV function, MR recurrence, survival and reoperation for the two groups with a greater tendency towards mitral stenosis development with the Duran ring, this being most likely due to late pannus formation.
Chang et al. [10] in their RCT enrolling 356 patients (Carpentier ring group, n=186; Duran ring group, n=170), with similar demographics, showed similar long-term outcomes as well as left ventricular systolic function measured with echocardiography for the two groups at a mean follow-up of 46.6 months. The 8-year freedom from recurrence of significant MR was 62.6±19.0% in the Carpentier ring group and 55.5±14.1% in the Duran ring group (P=0.172).
Shahin et al. [11] in their RCT comparing 96 patients randomised for either a Carpentier-Edwards rigid Classic (n=53) or a semi-flexible Physio (n=43) ring reported no differences in morbidity, valve function, and left ventricular function at a mean follow-up of 5.1 years.
Bevilacqua et al. [12] in a retrospective study of 133 patients, of whom 77 patients (57.9%) received a Carpentier-Edwards ring and 56 received (42.1%) an autologous pericardium ring, showed that 5-year freedom from reoperation and recurrence of mitral regurgitation  3+/4+ was significantly higher in the prosthetic ring group (90.1% – CL90%: 81.9–98.3%) compared with the pericardial ring group (62.6% – CL90%: 43.1–82.1%; P=0.027). The results of this study contradicted the results of an earlier small retrospective study by Milano et al. [13] which compared four different annuloplasty techniques in 62 patients: local posterior annuloplasty (group 1, n=10), rigid Carpentier ring (group 2, n=20), Duran ring (group 3, n=17), and posterior annular plication with autologous pericardium (group 4, n=15). Mean follow-up in the entire patient series was 31±12 months. One patient in group two required reoperation 14 months after MV repair. In all groups there was a significant improvement in NYHA functional class (from 2.7±0.6 to 0.9±0.5, P<0.001), with a reduction of left ventricular end-diastolic and end-systolic volumes (154±50 ml to 105±33 ml, P<0.001; and 64±23 ml to 52±22 ml, P<0.001). In patients of groups 2, 3 and 4, residual mitral incompetence at follow-up (0.8±0.9 in group 2, 0.8±0.7 in group 3, and 0.2±0.6 in group 4) was not significantly different from discharge. However, in group 1, a higher degree of residual mitral regurgitation was present at discharge (0.9±0.6) with a trend to progress at follow-up (1.6±0.5). The results of this study prompted the authors to conclude that autologous pericardium appears to be an excellent annuloplasty material.
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7. Clinical bottom line
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Current best available evidence suggests that in patients with a flexible annuloplasty ring compared to patients with a semi-rigid/rigid annuloplasty ring the improvement in LV systolic function reported by sophisticated echocardiographic studies does not translate into better clinical outcomes as clinical studies, including two RCTs, report comparable outcomes for patients with mitral regurgitation secondary to degenerative mitral valve disease requiring mitral valve repair with an annuloplasty ring.
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Abstract
1. Introduction