Author + information
- Steven F. Bolling, MD∗ ()
- ↵∗Reprint requests and correspondence:
Dr. Steven F. Bolling, Division of Cardiac Surgery, University of Michigan, 1500 East Medical Center Drive, 2120 TC/0348, Ann Arbor, Michigan 48109.
- left ventricular end-diastolic diameter
- mitral valve annuloplasty
- mitral valve insufficiency
- myocardial revascularization
- undersizing annuloplasty
- ventricular remodeling
In this issue of the Journal, Nappi et al. (1) publish a well-written paper, in which they present 5-year outcomes of a small clinical trial of 96 patients with severe ischemic mitral regurgitation (MR) undergoing coronary bypass as well as undersized mitral valve annuloplasty. In addition, one-half of the patients received a mitral subvalvular procedure: papillary muscle approximation or “sling.” The authors report significant beneficial improvements in left ventricular (LV) end-diastolic diameters, LV ejection fraction, and recurrence rates of MR at 5 years of follow-up, favoring the papillary muscle sling group. Although this trial was not powered for mortality, there was no statistical difference in mortality. Also, there appeared to be greater freedom from major adverse coronary and cerebrovascular events with the addition of a subvalvular sling. The authors concluded that papillary muscle approximation or sling had a long-term beneficial effect on LV remodeling and geometry compared with undersized-ring annuloplasty alone in ischemic MR.
It is hard to make broad conclusions from any particular ischemic MR study. This paper illustrates the difficulties of studying patients with ischemic mitral regurgitation. They are a heterogeneous, difficult group with numerous comorbidities. Ischemic MR patients do “poorly slowly” and are not amenable to mortality trials. Additionally, cardiac surgical prospective ischemic MR trials have been hard to enroll, because <10% of patients screened are randomized. Lastly, there are nonaccountable differences in surgeons and surgical techniques between trials. For example, in the New England Journal of Medicine, severe ischemic MR study (2), there was a large deviation in annuloplasty size and type with sizes up to 34 mm. Also, in the New England Journal of Medicine trial, the 2-year recurrence rate of moderate to severe mitral regurgitation was >50%. Conversely, in the present study, all patients received either a 26- or 28-mm undersized ring and recurrence rates of moderate to severe mitral regurgitation was only 13 to 15% at 2 years, regardless of treatment group. Although this may be partly explained by differences in ischemic MR group demographics, or to different revascularization strategies, a 3- or 4-fold difference in ischemic MR recurrence greatly alters any possible broad conclusions or cross comparisons.
Despite these challenges, a recent article in the Journal of Thoracic and Cardiovascular Surgery (3), the American Association of Thoracic Surgery consensus guidelines were published for the surgical treatment of ischemic mitral valve regurgitation. These guidelines take an in depth examination of all the ischemic MR studies and reinforce the concept that, much as in degenerative MR, that a good repair, without recurrence, remains better than replacement. Although it may be presently popular to state that IMR replacement and repair are functionally equivalent, by far the best LV remodeling occurs in the “good” repair group (4). Ischemic MR patients in the replacement group, although having statistically significant LV reduction in size, have only biologically unimportant LV decrease. These data point at the differential effects of eliminating MR and remodeling the LV. Furthermore, it has implications for percutaneous ischemic MR therapies, as the elimination of MR by large, bulky replacement prostheses may not allow for best or complete LV size reversal, analogous to the results seen with ischemic MR surgical mitral valve replacement. Therefore, identification of patients in whom we can ensure “good” repair is paramount. Percutaneous methods, timing of intervention and newer imaging techniques may help in this task. Conversely, we have learned to avoid repair in those ischemic MR patients with very large LVs and “basilar” segmental dyskinesia. However, the evaluation of different ischemic MR surgical techniques, such as shown by this paper (1), which may increase our ability to ensure ischemic MR patients have a “good repair” are of utmost importance.
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Dr. Bolling has reported that he has no relationships relevant to the contents of this paper to disclose.
- 2016 American College of Cardiology Foundation