Modified Surgical MV Repair Stands Up to Replacement

In patients with ischemic mitral regurgitation (MR), a repair technique that combines the use of a mildly undersized annuloplasty band plus edge-to-edge repair is associated with improved survival as compared with mitral valve (MV) replacement, according to a new study presented this week.

The reduction in mortality should be viewed as hypothesis-generating only, say investigators, but the study also suggested that this form of modified MV repair is associated with a similar rate of recurrent moderate MR at 2 years as MV replacement. Additionally, it showed no difference in the rate of reoperation between the two procedures.

“We know ischemic MR is deadly and associated with a very poor prognosis,” lead researcher Alex Nantsios, MD (University of Ottawa Heart Institute, Canada), told TCTMD. “It’s quite common in patients who present for surgical revascularization.” Moreover, ischemic MR remains a significant surgical challenge, he said.

The best evidence for treatment, said Nantsios, is from the Cardiothoracic Surgical Trials Network (CTSN) randomized trial, which compared traditional MV repair with MV replacement. While the study showed there was no difference in the rates of LV remodeling or survival at 2 years between the two surgeries, MV repair was associated with a significantly higher risk of recurrent moderate or severe MR at 2 years (58.8% with repair vs 3.8% with replacement; P < 0.001). That led to more heart failure-related hospitalizations and cardiovascular admissions.

“The study concluded that replacement was the way to go,” said Nantsios. “The traditional repair was just not durable.”

Since ischemic MR is typically caused by LV dysfunction and remodeling that results in a combination of annular dilatation and tethering of the posterior mitral leaflet, the traditional surgical approach for treatment has been to use a complete annuloplasty ring smaller than the patient’s mitral annulus. By implanting the downsized ring, operators reduce dilatation of the annulus and improve coaptation of the mitral leaflets, explained Nantsios.

However, in the years since the CTSN randomized trial, several mechanistic studies have hinted that downsizing the annuloplasty ring results in persistent tethering forces and these have been correlated with recurrent MR and poor durability, said Nantsios. For the modified procedure, surgeons hypothesized that by only mildly downsizing the annuloplasty ring, and using an incomplete band, this would limit the adverse forces and improve durability. All of the patients in this analysis also received edge-to-edge repair using the Alfieri stitch to further encourage coaptation.

Larger Rings and an Added Stitch  

The retrospective cohort study, which was presented at the Society of Thoracic Surgeons (STS) annual meeting, included patients undergoing surgery for ischemic MR between 2004 and 2020. Patients with primary MR, functional MR due to nonischemic cardiomyopathy, prior MV repair, and papillary muscle rupture were excluded from the analysis. Additionally, patients undergoing concomitant aortic-valve replacement were excluded. 

In total, 3,240 patients underwent MV surgery, of whom 1,371 also had documented coronary artery disease. Of these, 403 patients had a diagnosis of ischemic MR. After exclusions, including those who underwent a different repair procedure, the cohort study included 120 patients who underwent MV replacement and 90 who were treated with the mildly downsized annuloplasty ring plus edge-to-edge repair. The mean annuloplasty size was 30 mm in the present series, which is larger than the mean ring size of 27.9 mm used in the CTSN study.

There was no significant baseline difference between the two treatment groups, including the extent of LV remodeling. The percentage of patients with moderate-to-severe and severe MR was also similar between groups, as was the percentage of patients treated concomitantly with CABG surgery (84.2% with replacement and 81.7% with repair; P = 0.64).

At 2 years, 94.5% of patients treated with repair were alive compared with 85.7% of those treated with replacement (P = 0.018). The recurrence of mild-to-moderate MR (2+) was significantly higher among the repair patients (15.6% vs 1.2%; P < 0.001), but there was no difference in the recurrence of moderate or greater MR (2-3+). Rates of reoperation also were similar between treatments.  

In terms of deciding which ischemic MR patients should have their valves replaced in full rather than undergo repair with the combination procedure, Nantsios said surgical and clinical variables factor into the decision, but that ultimately it is surgeon preference.

“The surgeon needs to have enough confidence that they can create a good, durable repair,” he said. “Secondly, clinical differences in patients, particularly if the patient’s overall life expectancy won’t outlast the duration of a tissue valve, they may not benefit from a repair. Also, patients who are more critically ill, such as those in cardiogenic shock, where it is more crucial to ensure the reduction of the MR, replacement may be the better option.”

The study did not look at any anatomical aspects that might suggest certain patients fare better with MV repair or replacement, he said.

Joanne Chikwe, MD (Cedars-Sinai Medical Center, Los Angeles, CA), who moderated the STS session, said the significant reduction in MR in the repair group is an outstanding result, but questioned whether the edge-to-edge repair is necessary given that operators downsized the annuloplasty ring. She noted that studies have shown that mildly downsizing the annuloplasty ring can also result in a similar freedom from MR.  

In response, Nantsios noted that they have data on patients with ischemic MR who underwent repair with a mildly downsized annuloplasty ring only, and their early results suggest that the addition of edge-to-edge repair adds incremental benefit. On the flip side, he noted, studies of transcatheter edge-to-edge repair with MitraClip (Abbott) without concomitant annuloplasty have also shown significant reductions in MR in selected patients.

In terms of future directions, Nantsios stressed that prospective evidence would be warranted to confirm the improved outcomes with this repair technique.