Conference Coverage

Mini-invasive MV repair as safe, effective as sternotomy surgery but has advantages: UK Mini-Mitral Trial



Patients with degenerative mitral valve (MV) regurgitation that calls for surgery may, for the most part, safely choose either a standard procedure requiring a midline sternotomy or one performed through a minithoracotomy, suggests a randomized comparison of the two techniques.

Still, the minimally invasive approach showed some advantages in the study. Patients’ quality of recovery was about the same with both procedures at 12 weeks, but those who had the minimally invasive thoracoscopy-guided surgery had shown greater improvement 6 weeks earlier.

Also in the UK Mini Mitral Trial, hospital length of stay (LOS) was significantly shorter for patients who underwent the mini-thoracotomy procedure, and that group spent fewer days in the hospital over the following months.

But neither procedure had an edge in terms of postoperative clinical risk in the study. Rates of clinical events, such as death or hospitalization for heart failure (HHF), were about the same over 1 year.

Patients in this trial had been deemed suitable for either of the two surgeries, which were always performed by surgeons specially chosen by the steering committee for their experience and expertise.

This first randomized head-to-head comparison of the two approaches in such patients should make both patients and clinicians more confident about choosing the minimally invasive surgery for degenerative MV disease, said Enoch Akowuah, MD, Newcastle (England) University, United Kingdom.

Dr. Akowuah presented the UK Mini-Mitral Trial at the joint scientific sessions of the American College of Cardiology and the World Heart Federation.

A “main takeaway” for clinical practice from the trial would be that minithoracotomy MV repair “is as safe and effective as conventional sternotomy for degenerative mitral regurgitation,” said discussant Amy E. Simone, PA-C, following Dr. Akowuah’s presentation.

“I think this study is unique in that its focus is on delivering high-quality, cost-efficient care for mitral regurgitation, but also with an emphasis on patients’ goals and wishes,” said Ms. Simone, who directs the Marcus Heart Valve Center of the Piedmont Heart Institute, Atlanta.

Cardiac surgeon Thomas MacGillivray, MD, another discussant, agreed that the data presented from at least this study suggest neither the minithoracotomy nor sternotomy approach is better than the other. But he questioned whether that would hold true if applied to broader clinical practice.

Dr. MacGillivray, of MedStar Washington Hospital Center, Washington, observed that only 330 patients were randomly assigned among a total of 1,167 candidates for candidates for MV repair surgery.

Indeed, he noted, more than 200 declined and about 600 were declared ineligible for the study, “even though it had seemed as if all were appropriate for mitral valve repair. That could be viewed as a significant limitation in terms of scalability in the real world.”

Some of those patients weren’t randomly assigned because they ultimately were not considered appropriate for both procedures, and some expressed a preference for one or the other approach, Dr. Akowuah replied. Those were the most common reasons. Many others did not enter the study, he said, because their mitral regurgitation was functional, not degenerative.

The two randomization groups fared similarly for the primary endpoint reflecting recovery from surgery, so the trial was actually “negative,” Dr. Akowuah said in an interview. However, “I see it as very much a win for minithoracotomy. The outstanding questions for clinicians and patients have been about the clinical efficacy and safety of the technique. And we’ve shown in this trial that minithoracotomy is safe and effective.”

If the minithoracotomy procedure is available, he continued, “and it’s just as clinically effective and safe – and we weren’t sure that was the case until we did this trial – and the repair is almost as durable, then why have a sternotomy?”

The researchers assigned 330 patients with degenerative MV disease who were deemed suitable for either type of surgery to undergo the standard operation via sternotomy or the minithoracotomy procedure at 10 centers in the United Kingdom. The steering committee had hand-selected its 28 experienced surgeons, each of whom performed only one of the two surgeries consistently for the trial’s patients.

The technically more demanding minithoracotomy procedure took longer to perform by a mean of 44 minutes, it prolonged cross-clamp time by 11 minutes, and it required 30 minutes more cardiopulmonary bypass support, Dr. Akowuah reported.

The two patient groups showed no significant differences in the primary endpoint of physical function and ability to return to usual activity levels at 12 weeks, as assessed by scores on the 36-Item Short Form Survey and wrist-worn accelerometer monitoring. At 6 weeks, however, the mini-thoracotomy patients had shown a significant early but temporary advantage for those recovery measures.

The minithoracotomy group clearly fared better, however, on some secondary endpoints. For example, their median hospital LOS was 5 days, compared with 6 days for the sternotomy group (P = .003), and 33.1% of the mini-thoracotomy patients were discharged within 4 days of the surgery, compared with only 15.3% of patients who had the standard procedure (P < .001).

The minithoracotomy group also had marginally more days alive out of the hospital at both 30 days (23.6 days vs. 22.4 days in the sternotomy group) and 90 days (82.7 days and 80.5 days, respectively) after the surgery (P = .03 for both differences).

Safety outcomes at 12 weeks were similar, with no significant differences in rate of death, strokes, MI, or renal impairment, or in ICU length of stay or need for more than 48 hours of mechanical ventilation, Dr. Akowuah reported.

Safety outcomes at 1 year were also similar. Mortality by then was 2.4% for the minithoracotomy patients and 2.5% for the sternotomy group, nor were there significant differences in HHF rates or need for repeat MV surgical repair.

Dr. Akowuah said the patients will be followed for up to 5 years for the primary outcomes, echocardiographic changes, and clinical events.

The minithoracotomy surgery’s longer operative times and specialized equipment make it more a expensive procedure than the standard surgery, he said. “So we need to work out in a cost-effectiveness analysis whether that is offset by the benefits,” such as shorter hospital stays or perhaps fewer transfusions or readmissions.

The study was funded by the United Kingdom’s National Institute for Health and Care Research. Dr. Akowuah reported no relevant financial relationships with industry.

A version of this article first appeared on

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