Subannular repair for moderate to severe ischemic mitral regurgitation: Still a long way to go. Authors' reply.

I thank the author for the letter “Moderate to severe ischemic mitral regurgitation: More data to guide the choice. Why not consider the use of subvalvular repair? ” [1]. As presented in the original article “Long-term outcomes of mitral valve annuloplasty versus subvalvular sparing replacement for severe ischemic mitral regurgitation” [2], ring annuloplasty (RA) was performed without subvalvular repair, which was in according with the practice guidelines [3]. In addition, it was found that compared with the mitral valve replacement group, the incidence of mitral regurgitation recurrence was significantly higher in the RA group (p < 0.001) [3]. Ischemic mitral regurgitation (MR) is frequently associated with myocardial infarction. With the dilatation of the ventricle, the papillary muscles are displaced, and the leaflets are pulled downward and laterally. In the most frequent inferior infarction, this leaflet tethering is observed in the area of the posteromedial commissure. What is more, the annulus dilates secondarily to both the dilatation of the ventricle and the MR, which enters a vicious cycle [3, 4, 5]. According to practice guidelines, mitral valve (MV) repair with an undersized complete rigid annuloplasty ring may be considered in patient with severe ischemic MR who remain symptomatic despite guideline directed medical and cardiac device therapy and who do not have a basal aneurysm/dyskinesis, significant leaflet tethering, or severe left ventricular enlargement (COR IIb, LOE B) [3]. Though there are different kinds of techniques for MV repair, such as annuloplasty and subannular repair [4, 6–9], guidelines do not specifically point out which of the currently available valve repair approaches are superior. In accordance with practice guidelines, the technique of RA was easy-to-accomplish, effective and safe, it is also common at the documented center, these results are shown in a retrospective study [2]. According to the Alain Carpentier functional classification, MR of type I is characterized by annular dilation, while type IIIb is characterized by restricted motion of the leaflets because of tethering [8, 10]. As documented in the results of recent studies, both of type I and type IIIb are common for ischemic MR, and ischemic MR is a secondary pathology where the underlying mechanism is not eradicated by either subannular repair or RA alone [4, 5]. Undersized RA. Undersized RA is designed to correct MR of type I. Although it is perhaps less technically challenging and associated with lower shortterm complication rates, the high rate of recurrent MR after repair attenuates the potential benefit of RA. Several studies have suggested that posterior leaflet tethering after undersized RA is the main underlying mechanism associated with MR recurrence [7, 10]. Capoulade et al. [10] concluded that left ventricular ring mismatch was associated with significant recurrent MR in patients after undersized RA. Subannular repair. Because misalignment of the papillary muscles appears to be the main problem, techniques directed at papillary muscle realignment have been suggested, and two techniques are available in the literature.