The largest randomised controlled trial to date to compare minimally invasive and conventional cardiac surgery in the mitral valve—UK Mini Mitral—has found surgical outcomes and quality of life to be similar in patients who received either technique for mitral valve repair at 12 weeks post-procedure.
Presented at the American College of Cardiology (ACC) annual Scientific Session (4–6 March, New Orleans, USA), lead author Enoch Akowuah (Newcastle University, Newcastle upon Tyne, UK) investigated patients with severe degenerative mitral valve regurgitation to assess recovery and subsequent complications.
The study included 330 patients treated at 10 centres across the UK—the cohort’s average age was 67 years—30% of whom were women. Participants were randomly assigned to undergo mitral valve repair by either sternotomy or mini-thoracotomy.
Expertise randomisation was a focal area of the study—28 surgeons were approved by the Trial Steering Committee and were required to have performed at least 50 procedures—and Akowuah stated that this was based on patient feedback prior to the study’s design to “remove the learning curve” and assure patients would receive a “high-quality procedure” regardless of group designation.
The researchers outlined their primary endpoint as the change in patients’ physical functioning and ability to carry out day-to-day activities at 12 weeks post-procedure. This was measured by changes in SF-36v2 quality-of-life and physical functioning scale from baseline. Akowuah et al assessed changes through periodic questionnaires and updates via an accelerometer that patients wore on their wrists.
Defining their secondary endpoint, the researchers included physical function at six weeks, physical activity and sleep efficiency measure via accelerometery at both six and 12 weeks, MVr rates, quality of mitral valve repair and adverse events, such as death, stroke, heart failure and repeat intervention.
When assessed at 12 weeks, Akowuah and colleagues found physical function levels pre- and post-surgery were similar in both groups. Although at six weeks, they noted, patients who underwent mini-thoracotomy had recovered physical function compared to pre-surgery, whereas patients who received a sternotomy had not.
At one year follow-up, Akowuah et al recorded that all secondary outcomes were not significantly different between the two groups. Despite one mini-thoracotomy patient requiring a secondary operation due to bleeding, the researchers found mini-thoracotomy patients typically spent a median of five days in hospital—compared to six days for sternotomy patients—and were more likely to be discharged early.
Reflecting on the significance of their findings, Akowuah highlighted that speed of recovery to ultimately regain physical function and return to normal activities is important for patients. “Our results show that at three months, physical recovery is equivalent in both groups of patients,” he said. “In addition, we show that when both surgical procedures are performed by expert surgeons, minimally invasive mitral valve surgery is as safe and effective as conventional surgery.”
Answering focal questions about the effectiveness of approaches, the authors state their study confirms the valve repair rate and the quality and durability of valve repair when using mini-thoracotomy, Akowuah asserted: “Valve repair rates were excellent [at 96%] and similar to those obtained with sternotomy. Moreover, at one year after surgery more than 92% of patients in both groups had no or mild valve leakage.”
The researchers convey that specialists have been reluctant to adopt mini-thoracotomy due to a lack of evidence confirming its safety and effectiveness. However, they state their research supports its use in patients who are “often younger and still working”, for whom a shorter hospital stay would be preferable. Akowuah concludes: “We hope that the results of this trial will give confidence to both clinicians and patients and drive uptake of the mini approach.”
