Minimally Invasive Thoracoscopically-Guided Right Minithoracotomy Versus Conventional Sternotomy for Mitral Valve Repair - UK Mini Mitral

Contribution To Literature:

In the UK Mini Mitral trial, a minimally invasive right thoracotomy approach to MV repair did not show differences in physical functioning at 12 weeks compared with a traditional sternotomy approach.


The goal of the trial was to compare the safety and efficacy of mitral valve (MV) repair done via a minimally invasive approach vs. conventional sternotomy among patients with degenerative mitral regurgitation (MR) who were surgical candidates.

Study Design

Patients were randomized in a 1:1 open-label fashion to MV repair either via a minimally invasive right thoracotomy approach (n = 166) or conventional sternotomy (n = 163). All patients were suitable for either approach. Surgeons doing these procedures had to be experts in that particular approach (12 for mini-MV repair, median 86 lifetime; 16 for sternotomy, median 162). Patients were required to move to one of these surgeons depending on randomization. MV repair techniques were at the discretion of the operating surgeon.

  • Total screened: 1,167
  • Total number of enrollees: 329
  • Duration of follow-up: 1 year
  • Mean patient age: 67 years
  • Percentage female: 30%

Inclusion criteria:

  • Adult (≥18 years old at consent) patients with degenerative MV disease, requiring isolated MV repair (patients requiring concomitant surgery for atrial fibrillation and/or patent foramen ovale closure were included)
  • Fit for cardiac surgery and cardiopulmonary bypass

Other salient features/characteristics:

  • Atrial fibrillation: 42%
  • Urgent surgery: 10%
  • EuroSCORE II: 1.7
  • Severe MR: 93%
  • Leaflet pathology type II: 96%

Principal Findings:

The primary composite outcome, change in physical function at 12 weeks from baseline, for mini-MV repair vs. conventional sternotomy MV repair, was not statistically different (T-score: 0.68, 95% confidence interval -1.89 to 3.26; p = 0.61).

Scores for mini-MV repair increased significantly from baseline to 6 weeks, but not for sternotomy.

Secondary outcomes for mini-MV repair vs. conventional sternotomy MV repair:

  • Death at 12 weeks: 0.6% vs. 2.5% (p = 0.2)
  • Stroke with permanent deficit: 0.6% vs. 3.1% (p = 0.13)
  • Hospital length of stay: 5 vs. 6 days (p = 0.003)
  • Early discharge (≤4 days postop): 33.1% vs. 15.3% (p < 0.001)
  • Death at 1 year: 2.4% vs. 2.5% (p = 0.98)
  • Repeat MV surgery: 0% vs. 0.6% (p = NS)


The results of this trial indicate that a minimally invasive right thoracotomy approach to MV repair did not show differences in physical functioning at 12 weeks compared with a traditional sternotomy approach. Both surgeries were performed by surgeons with an expertise in that particular procedure. Procedure and cross-clamp times were longer for mini-MV repair, but overall patient length of stay was shorter. Clinical outcomes were similar up to 1 year of follow-up.

These are encouraging results and suggest that when surgical expertise is available, mini-MV repair may be the preferred approach for patients needing surgery for degenerative MR. Long-term durability of repair and cost-effectiveness analyses are awaited.


Presented by Dr. Enoch Akowuah at the American College of Cardiology Annual Scientific Session (ACC.23/WCC), New Orleans, LA, March 5, 2023.

Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Congenital Heart Disease and Pediatric Cardiology, Invasive Cardiovascular Angiography and Intervention, Valvular Heart Disease, Atrial Fibrillation/Supraventricular Arrhythmias, Cardiac Surgery and Arrhythmias, Cardiac Surgery and CHD and Pediatrics, Cardiac Surgery and VHD, Congenital Heart Disease, CHD and Pediatrics and Arrhythmias, CHD and Pediatrics and Interventions, Interventions and Structural Heart Disease, Mitral Regurgitation

Keywords: ACC23, ACC Annual Scientific Session, Atrial Fibrillation, Cardiac Surgical Procedures, Cardiopulmonary Bypass, Foramen Ovale, Patent, Heart Valve Diseases, Length of Stay, Mitral Valve, Mitral Valve Insufficiency, Patient Discharge, Sternotomy, Stroke, Thoracotomy

< Back to Listings