Should edge-to-edge fixation be routine?

In this issue of the journal, De Bonis et al. [1] conclude that the edge-to-edge technique should not be performed routinely with a restrictive annuloplasty for functional mitral regurgitation (MR), because the procedure did not improve the clinical outcomes compared with those of an annuloplasty alone. However, the data presented are also insufficient to justify their contention that the addition of this manoeuvre will reduce recurrent MR. De Bonis and colleagues reviewed their database and extracted patients who had an ejection fraction less than 35% and then compared those who had a mitral valve repair with a restrictive annuloplasty with or without an edge-to-edge procedure. The question they are asking is very important—does the addition of edge-to-edge technique to mitral repair reduce the risk of recurrence MR and does it improve clinical outcomes? However, the answer to this question is elusive. Edge-to-edge fixation is an important adjunct to mitral repair for functional MR and may become an important addition to the surgical armamentarium. The authors describe in detail the pathological conditions where this manoeuvre was employed to enhance the results achieved with a restrictive annuloplasty. The outcomes in these carefully selected cases were very good and the authors should be congratulated for bringing this approach to the readers of the Journal. Under the conditions they describe, the edge-to-edge fixation may be very appropriate. However, to determine whether this approach is better than annuloplasty alone to reduce recurrent MR is very difficult because they need to compile patients who had the same pathology exactly. Instead, they compared those who did with those who did not have an edge-to-edge repair. Because the two groups of patients had a different mixture of pathologies, they are comparing apples and oranges. A propensity analysis might permit a better comparison if the patients in the two groups can be matched [2]. However, the authors declined the recommendation to perform propensity matching. Comparing their results with other reports in the literature is also very difficult because of the broad range of pathologies included in their analysis. Similar to their previous report [3], De Bonis et al. combined patients with different aetiologies of MR and a wide range of disease processes for this comparison. They employed the edge-to-edge technique for patients with both ischaemic and non-ischaemic cardiomyopathy and combined patients with moderate and severe mitral insufficiency. Previous studies found that the addition of the edge-to-edge fixation did not prevent progressive MR recurrence in patients with an ischaemic cardiomyopathy [4]. Although that study was limited because of the incomplete annuloplasty ring employed, it emphasizes the importance of a thorough comparison. Patients with an ischaemic aetiology may have different risks than those with idiopathic dilated cardiomyopathy. Patients with reversible ischaemia receiving bypass grafts would be expected to have a lower rate of recurrent MR than those with a non-ischaemic, but progressive cardiomyopathy. Ischaemic mitral insufficiency frequently has an unpredictable outcome after a coronary artery bypass grafting (CABG) with or without mitral valve repair. In addition, the severity of the preoperative MR will also influence the outcome. The Cardiothoracic Surgical Trials Network (CTSN) integrated multiple measurements to permit the accurate differentiation of moderate from severe MR [5–8]. Moderate MR was: an effective regurgitant orifice area between 0.2 and 0.4 cm2, a vena contracta width of 3–7 mm and a ratio of the mitral regurgitant jet area to the left atrial area of 20–40%. Severe MR included patients with greater degrees of regurgitation. Patients with ischaemic cardiomyopathy have different options based on the degree of preoperative regurgitation. These patients have the greatest need for a durable repair and might benefit most from the addition of the edge-to-edge manoeuvre. However, these patients were not separately evaluated in this report. The CTSN randomized trial suggested that mitral replacement provided a more durable correction of the MR than an undersized annuloplasty but without a difference in clinical outcomes [5, 6]. The authors may have employed replacement preferentially for this group and included in this study, only a few patients who they anticipated would do well with an edge-to-edge fixation and annuloplasty. The major question for this subgroup is whether a durable repair can be achieved or whether a replacement should be performed. The authors should provide their results with replacement, annuloplasty and annuloplasty plus edge-to-edge repair in this important subgroup. Then, the benefits of edge-to-edge fixation can be determined. Many of these patients will have an improvement in their MR with CABG alone particularly if they have extensive reversible ischaemia. The CTSN randomized trial found that mitral repair with a restrictive annuloplasty significantly reduced the recurrence of MR compared with CABG alone, but was associated with a greater number of serious neurological events and supraventricular arrhythmias [7, 8]. The outcomes among these patients should be reported by the authors. The results in this subgroup may represent careful patient selection. Presumably, the majority of the 69 ischaemic patients in this report had moderate MR. Was the number of patients with moderate ischaemic MR balanced in the two groups? The edge-to-edge repair may be particularly beneficial in this group, but the results with annuloplasty or CABG alone were also better than in those with severe preoperative MR. The authors should report their results with CABG alone, annuloplasty alone and the combination of annuloplasty and edge-to-edge repair in this subgroup. Even among the carefully selected patients who had the edge-to-edge manoeuvre, was the combination better than CABG alone? Only a more extensive evaluation will determine the potential benefits of this technique. In summary, the authors report a lower rate of recurrent MR when the edge-to-edge repair was added to a restrictive annuloplasty for functional MR. However, the heterogeneity and small patient numbers limit their ability to accurately compare the two groups. In addition, the ischaemic MR patients were not evaluated separately. Subgroup unbalance between the two groups for the two ischaemic subgroups could have influenced the reported outcomes. The edge-to-edge repair may be an important addition to mitral repair, but a more extensive evaluation will be required to establish which patients benefit. Until a more critical comparison has been made, edge-to-edge fixation should not be applied routinely.

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