Mitral valve repair: Two surgeries have similar successful results

• A new study is the first randomized clinical trial to compare mitral valve repair via a conventional sternotomy.
• Researchers report that recovery from baseline to 6 weeks is better with mini-mitral surgery, although at 12 weeks, recovery of physical function is the same for both mini-mitral and sternotomy.
• A high mitral valve repair rate was seen with both surgical approaches and there were no differences in key safety outcomes.
• Researchers say the findings should give confidence to patients that mini-mitral surgery is as safe and efficacious as conventional sternotomy when performed by an experienced surgeon.

The mitral valve in the heart works like a door between two of the heart’s chambers (the left atrium and the left ventricle).

It ensures that blood flows from the left atrium (upper chamber) to the left ventricle (lower chamber).

Mitral valve regurgitation is a condition where the mitral valve doesn’t close properly, so some of the blood flows backward.

This makes the heart work harder to pump enough blood to the body. Symptoms include fatigue and shortness of breath.

In some cases, doctors may prescribe medication to treat mitral valve regurgitation.

Another option is mitral valve repair surgery. This can be done in different ways, including:

• Conventional surgery via a sternotomy – This involves opening the chest completely from the collarbone to the bottom of the breastbone. The healing process after the operation is lengthy.
• Minimally invasive mitral valve repair via a mini-thoracotomy, also known as “mini-mitral.” This involves making an incision about two inches long in the chest to gain access to the heart and then using a camera and special instruments to repair the valve. Recovery time is shorter, but the procedure is more complex.

There has been widespread debate in the cardiac surgery community about which one of the two approaches is best. Although patients prefer the minimally invasive mini-mitral approach, there have been concerns about its clinical efficacy compared to a traditional sternotomy.

There have also been questions about its safety as early studies suggested the ‘mini-mitral’ procedure might have an increased risk of complications, including stroke.

To answer these questions, researchers at Newcastle University in England, led by professor of cardiac surgery Dr. Enoch Akowuah, designed a randomized clinical trial to compare the two surgical techniques.

The results of the UK Mini Mitral study, which haven’t been published yet in a peer-reviewed journal, were presented at the American College of Cardiology’s 2023 Scientific Session.

Dr. Donald Glower, a professor of surgery at Duke University School of Medicine who was not involved in the study, told Medical News Today that this is “a rare randomized trial” that “suggests that equivalent results can be obtained by either approach, with faster recovery with mini-mitral.”

Dr. James S. Gammie, a senior professor of cardiac surgery at John Hopkins Medicine in Maryland who also was not involved in this study, commented that “Akowuah and colleagues deserve congratulations for conducting [this] rigorous prospective randomized trial.”

Details from the mitral valve repair surgery study

The study recruited adults who needed to undergo mitral valve repair and who were eligible for either surgical approach.

The researchers randomized study participants from 10 sites in England and Scotland to mini-mitral surgery or sternotomy.

Procedures were performed by 28 surgeons who were considered experts based on a history of at least 50 completed operations.

The primary question that Akowuah’s team sought to answer was whether a person’s return to physical function and usual activities was better after mini-mitral surgery compared to conventional surgery.

At 6 and 12 weeks, the study participants were asked to wear a Fitbit-like device called an accelerometer for a week at a time to measure their physical activity and sleep efficiency.

Other important secondary outcomes measured in this study were: mitral valve repair rates; quality of mitral valve repair (rate of moderate or severe mitral regurgitation at 12 weeks and 1 year); and adverse events (death, stroke, heart failure hospitalization, and repeat intervention on the mitral valve).

Key findings from the mitral valve repair research

In total, 329 individuals were randomized to either treatment approach. The mean age of study participants was 67 and 30% were women.

For people who had conventional surgery, at 6 weeks after the procedure, physical function was not improved relative to baseline. It takes 12 weeks for a significant improvement from baseline to be observed, the researchers reported.

In contrast, people who had mini-mitral surgery had significantly higher physical function scores compared to baseline at 6 weeks, indicating that they have already recovered from their operation, the researchers noted.

At 12 weeks, both groups had recovered from surgery, which means that the difference in the change in physical function from baseline to 12 weeks between groups was not significant.

The researchers observed that people in the mini-mitral surgery group spent significantly more time doing moderate and vigorous physical activity, such as running, walking and swimming, and had better sleep efficiency, compared to people in the sternotomy group.

Additionally, people who underwent mini-mitral surgery had shorter hospital stays and were twice as likely to be discharged early.

A high repair mitral valve repair rate was seen for both approaches: 97% for sternotomy and 95% for mini-mitral.

The safety profile of the two approaches was similar, with a mortality rate of 2.5% for sternotomy and 0.6% for mini-mitral at 12 weeks.

At 1 year, both groups had successful echocardiographic outcomes (92% had no or mild mitral regurgitation) indicating good valve repair durability.

There was no difference in important safety outcomes (death, heart failure hospitalization, repeat operation) at 1 year.

How will these findings affect clinical practice?

Globally, the majority of people undergoing mitral valve repair have a sternotomy and a smaller proportion have mini-mitral surgery.

Gammie said that “just over 30 percent of isolated mitral valve operations in North America are performed using a right-chest [mini-mitral] approach.”

One of the factors that has been limiting the uptake of mini-mitral surgery has been the uncertainty about the safety and efficacy of the technique.

The UK Mini Mitral study is the first randomized clinical trial to show that mini-mitral surgery is as safe and efficacious as a conventional sternotomy. Akowuah and coworkers hope that this new knowledge will increase adoption of the mini-mitral technique internationally.

Gammie said that “[t]he trial did not demonstrate superiority of right chest thoracotomy over conventional sternotomy.” His opinion is that “the most important measure of success in mitral valve surgery is the rate of repair for degenerative disease, and it should approximate 100 percent… Repair affords a patient both short- and long-term benefits.”

“I have had a number of patients with both a right thoracotomy and a sternotomy (either concurrent or contemporaneous) and universally patients report that a right chest approach hurts more,” Gammie added.

Mini-mitral surgery has a substantial learning curve for surgeons

Mini-mitral surgery is a complex technique and surgeons need significant experience to achieve expertise.

Gammie described it as “an art that requires substantial experience to develop.” He added that surgeons typically require between 75 and 125 operations to master the technique.

“The UK mini-mitral trial reassures the community that in experienced hands, right thoracotomy approach to mitral valve repair can yield equivalent results to conventional sternotomy. In less experienced hands, focus on repair via a sternotomy is probably the safest approach,” he said.

Glower echoed the thought that surgeon expertise determines the outcome.

“[T]his trial with experienced teams does not mean that less experienced teams with lower volumes with either approach will be able to duplicate the results,” he said.

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