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Original research article
Propensity-matched analysis of minimally invasive approach versus sternotomy for mitral valve surgery
  1. Stuart W Grant1,
  2. Graeme L Hickey2,
  3. Paul Modi3,
  4. Steven Hunter4,
  5. Enoch Akowuah5,
  6. Joseph Zacharias6
  1. 1 Institute of Cardiovascular Sciences, University of Manchester, ERC, Manchester, UK
  2. 2 Department of Statistics, Medtronic, Coronary and Structural Heart, Watford, UK
  3. 3 Department of Cardiac Surgery, Liverpool Heart and Chest Hospital, Liverpool, UK
  4. 4 Department of Cardiac Surgery, Sheffield Teaching Hospitals NHS Foundation Trust, Chesterman Wing, Northern General Hospital, Sheffield, UK
  5. 5 Department of Cardiac Surgery, South Tees NHS Foundation Trust, The James Cook University Hospital, Middlesbrough, UK
  6. 6 Department of Cardiothoracic Surgery, Lancashire Cardiac Centre, Blackpool, UK
  1. Correspondence to Stuart W Grant, Academic Surgery Unit, ERC, Wythenshawe Hospital, Manchester M23 9LT, UK; stuart.grant{at}


Objective The objective of this multicentre study was to compare short-term and midterm outcomes between sternotomy and minimally invasive approaches for mitral valve surgery.

Methods Data for all mitral valve procedures with or without concomitant tricuspid atrial fibrillation surgery were analysed from three UK hospitals between January 2008 and December 2016. To account for selection bias between minimally invasive approach and sternotomy, one-to-one propensity score calliper matching without replacement was performed. The main outcome measure was midterm reintervention free survival that was summarised by the Kaplan-Meier estimator and compared between treatment arms using the stratified log-rank test.

Results A total of 2404 procedures (1757 sternotomy and 647 minimally invasive) were performed during the study period. Propensity score matching resulted in 639 matched pairs with improved balance postmatching in all 31 covariates (absolute standardised mean differences <10%). Despite longer procedural times patients who underwent minimally invasive surgery had a lower need for transfusion (20.5%vs14.4%, p=0.005) and reduced median postoperative length of stay (7 vs 6 days, p<0.001). There were no statistically significant differences in the rates of in-hospital mortality or postoperative stroke. Reintervention-free survival at 8 years was estimated as 86.1% in the minimally invasive group and 84.1% in the sternotomy group (p=0.40).

Conclusions Minimally invasive surgery is associated with excellent short-term outcomes and comparable midterm outcomes for patients undergoing mitral valve surgery. A minimally invasive approach should be considered for all patients who require mitral valve intervention and should be the standard against which transcatheter mitral techniques are compared.

  • valve disease surgery
  • mitral regurgitation
  • mitral stenosis
  • quality and outcomes of care

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  • Contributors All authors contributed to the design of the study. SWG and GLH acquired and cleaned the data, performed the analyses and wrote the first draft of the manuscript. PM, SH, EA and JZ contributed data. All authors designed the project and revised the drafts. All authors read and approved the final manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests GLH is currently an employee of Medtronic Ltd; however, all work for this study was performed while he was employed at the University of Liverpool. SH has acted as a consultant for Edwards Lifesciences and Atricure BLV. JZ has acted as a proctor and received speaking fees from Edwards Lifesciences, Abbott and Cryolife.

  • Patient consent Not required.

  • Ethics approval The study was approved by the Liverpool Heart and Chest Hospital Ethical Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Data used for the study can be made available upon request if approval from the individual participating centres is obtained.