Flattening The Learning Curve; Propensity Score Matched Analysis Of First 50 Minimally Invasive Mitral Valve Repairs Versus Full Sternotomy
Momna S. Raja, Joon Lee, Ashok Narayanasamy, Uday Trivedi, Ishtiaq Ahmed.
Royal Sussex County Hospital, Brighton, United Kingdom.
Background: Minimal Invasive Mitral Valve Repair(MIMVr) is an established practice in many high-volume centres globally. However, there has been a low adoption of this technique in the United Kingdom. One barrier is the steep learning curve which has discouraged low-volume centres from engaging. Previous literature reports an experienced surgeon needs to perform 75-125 operations before achieving optimum results. We aim to evaluate the safety and effectiveness of our established minimally invasive mitral valve programme in comparison to propensity score matched full sternotomy cohort.
Methods: We did a retrospective analysis our first 50 MIMVr(via right mini-thoracotomy) patients when starting our minimally invasive programme. All MIMVr patients were carefully selected after their pre-operative 3D echos and CT imaging was discussed in a multidisciplinary team meeting consisting of Cardiac Surgeons, Radiologists and Echocardiographers, to allow for individualised procedural planning. All pre-, post- and 1-year follow-up data was collected using the trust's internal data base and MetaVision[iMDsoft]. MIMVr were propensity score matched(PSM) to full sternotomy(FSMVr) via the Matchit package in R. This was done to reduce the effect of confounding baseline patient demographics on outcomes. 45 well-matched pairs were identified. The primary outcomes were 30-day mortality, stroke, rate and volume of blood product transfusions, ICU and hospital stay.
Results: After PSM, there was no significant difference in baseline characteristics of MIMVr and FSMVr patients. There was a 100%(n=45) repair rate in both groups. 30-day mortality was lower in MIMVr compared to FSMVr[0% (n=0) v 2.2%(n=1),p>0.9]. One MIMVr patient had post-operative stroke. Intraoperatively, MIMVr patients spent 75 minutes(95%CI;57,88) and 38 minutes(95%CI;25,49) longer on cardiopulmonary bypass(CBP) and total cross clamp time(CCT)[p<0.01 for both]. There was a trend towards less need for transfusions[42%(n=19) vs 49%(n=22),p=0.66]. MIMVr had less volume of blood and blood products transfused 48-hours post-surgery. Lastly, they spent less time in ICU[74(95%CI:50,122)vs89(95%CI:55,110)hours,p>0.9] and total hospital stay[5(95%CI:4,8)vs7(95%CI:6,9)days,p<0.05].
Conclusion: We have demonstrated that it is possible to set up a MIMVr programme with results comparable to FSMVr with a much shorter learning curve than previously described. The key to a sustainable programme is a team-based approach, appropriate training and careful patient selection using CT and TOE.
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