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Correspondence

Are Rigid Annuloplasty Rings Better Than Flexible Annuloplasty Rings in Ischemic Mitral Regurgitation Repair: Where is the Evidence?

Department of Surgery, Raja Isteri Pengiran Anak Saleha Hospital, Bandar Seri, Begawan, BA1710 Brunei Darussalam

(Email: chong_chee_fui{at}hotmail.com).

To the Editor:

I read with interest the article by Silberman and colleagues [1] regarding the comparison of flexible annuloplasty rings with rigid rings in ischemic mitral valve repair and the discussions that followed. Although there is some indirect evidence indicating that rigid annuloplasty rings may be better than flexible rings in restrictive mitral valve annuloplasty (RMVA) for ischemic mitral regurgitation, I do not believe that this article contributes to that evidence [1, 2]. There are several faults in the methodology of the article that seems to have been totally missed in the subsequent discussions. For one, there is a large difference in terms of follow-up period between the flexible ring group (58 ± 30 months) and the rigid ring group (14 ± 7 months).

The incidence of failure after RMVA can be as great as 30%, and it is believed to be due to the continual negative left ventricular (LV) remodeling with time, despite ring annuloplasty, resulting in increasing LV volume and sphericity index [3, 4]. The failure rate is higher in patients with larger interpapillary muscle distance preoperatively [3]. This causes persistent mitral valve leaflet tethering from LV dilatation that is not relieved by ring annuloplasty [4].

Thus, given the longer follow-up period in the flexible ring group, the higher incidence of residual MR of moderate degree or greater in the flexible ring group (twice that of rigid group) reported by Silberman and colleagues [1], could be explained by the difference in follow-up. Furthermore, the two groups are not comparable in terms of completeness of revascularization. This is obviously an important factor particularly in this group of patients with ischemic mitral regurgitation and the higher incidence of residual mitral regurgitation in the flexible ring group could also be due to persistent ischemia.

Last, the temporal difference in usage of the two ring types is important in terms of learning curve and improvement of surgical techniques over time, which will of course be biased toward the rigid ring annuloplasty group that was carried out in the latter 2 years (2005–2006) of the study. A better comparison would have been to compare the results of the flexible ring group from the same time period.

Spoor and colleagues [2] in their study reported significantly lower failure rates with rigid annuloplasty rings, which also tend to occur later than flexible rings in RMVA. Performing ring annuloplasty only fixes the septal-lateral annular dimension and prevents lateral displacement of the lateral annulus, thus reducing systolic septal-lateral leaflet separation [5]. The flexible ring, however, permits some degree of posterior displacement of the posterior leaflet edge and the lateral annulus, which are not observed with a semi-rigid or rigid annuloplasty ring, which may have explained the higher failure rates associated with flexible annuloplasty ring compared with rigid annuloplasty ring in RMVA [5].

	References

Top References

 

1. Silberman S, Klutstein MW, Sabag T, et al. Repair of ischemic mitral regurgitation: comparison between flexible and rigid annuloplasty rings Ann Thorac Surg 2009;87:1721-1727.[Abstract/Free Full Text]
2. Spoor MT, Geltz A, Bolling SF. Flexible versus nonflexible mitral valve rings for congestive heart failure: differential durability of repair Circulation 2006;114:I67-I71.[Medline]
3. Roshanali F, Mandegar MH, Yousefnia MA, Rayatzadeh H, Alaeddini F. A prospective study of predicting factors in ischemic mitral regurgitation recurrence after ring annuloplasty Ann Thorac Surg 2007;84:745-749.[Abstract/Free Full Text]
4. Hung J, Papakostas L, Tahta SA, et al. Mechanism of recurrent ischemic mitral regurgitation after annuloplasty: continued LV remodeling as a moving target Circulation 2004;110:II85-II90.[Medline]
5. Lai DT, Timek TA, Tibayan FA, et al. The effects of mitral annuloplasty rings on mitral valve complex 3-D geometry during acute left ventricular ischemia Eur J Cardiothorac Surg 2002;22:808-816.[Abstract/Free Full Text]

This article has been cited by other articles:

				S. Silberman Reply Ann. Thorac. Surg., December 1, 2009; 88(6): 2073 - 2074. [Full Text] [PDF]

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Chee Fui Chong Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Chong, C. F. Search for Related Content PubMed PubMed Citation Articles by Chong, C. F. Related Collections Valve disease Related Article