Implementation of Minimally Invasive Mitral Valve Surgery in a Novice Center

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The publication is devoted to a modern topic: on the one hand controversial in everyday cardiac surgery, on the other hand requiring further development and justification. The authors have clearly defined the tasks for the introduction of minimally invasive mitral valve surgery in their clinic and their consistent fulfillment. All stages of this preparation are clearly described: selection of patients, technologies used in preoperative diagnosis, technique and instrumentation of surgical interventions. And most importantly, the preparation of the surgical team! In favor of the convincing of the results obtained, a thorough statistical processing of the performed operations is also indicated. The literature review is unobjectionable. The manuscript can be published.

Author Response

Comment 1: The publication is devoted to a modern topic: on the one hand controversial in everyday cardiac surgery, on the other hand requiring further development and justification. The authors have clearly defined the tasks for the introduction of minimally invasive mitral valve surgery in their clinic and their consistent fulfillment. All stages of this preparation are clearly described: selection of patients, technologies used in preoperative diagnosis, technique and instrumentation of surgical interventions. And most importantly, the preparation of the surgical team! In favor of the convincing of the results obtained, a thorough statistical processing of the performed operations is also indicated. The literature review is unobjectionable. 

Response 1: The authors thank the reviewer for the extensive review and comments. The authors agree with the reviewer about the value of the entire teams preparation.

Comments 2: The manuscript can be published.

Response 2: The authors thank the reviewer for the response.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript is well written and the subject is interesting. Congratulations on the study. However, I would like to issue several recommendations:

1. The abstract is much too concise. Please provide few details in the background and the material and methods (e.g. number of patients included)
2. The material and methods section is written pretty long, maybe it would benefit from several bullet points.
3. The results are presented very schematic, as opposed to the previous section, may here several paragraphs could be used.

Otherwise, the manuscript is excelent. Congratulations!

Author Response

The manuscript is well written and the subject is interesting. Congratulations on the study. However, I would like to issue several recommendations:

comment 1: The abstract is much too concise. Please provide few details in the background and the material and methods (e.g. number of patients included)

Response 1: The authors thank the reviewer for the extensive and insight-full review and have added data in the abstract:

Line  12-15 now reads (Bold is new): The complexity of Minimally Invasive Mitral Valve Surgery (MIMVS) could cause a slow learning curve and potentially patient harm. We thus investigated if a novice mitral valve center encounters difficulties implementing MIMVS, one hundred thirty in each group. Surgical- (5.5 vs 4.3h), Cardiopulmonary bypass- (180 vs 102 min) and aortic cross-clamp times (98 vs. 81 min) became longer after MIMVS introduction. 

Line 15-16 now reads (Bold is new): We investigated seven hundred and forty eight mitral valve surgery patients, two years before and after MIMVS introduction

Comment 2: The material and methods section is written pretty long, maybe it would benefit from several bullet points.

Response 2: The authors have bullet pointed sections in the method section.

Line 60 now reads (Bold is new): 2.1 Implementation. ...

Line 73-6 has been omitted:

The primary investigator (AK) surveyed all completed cardiac surgeries in the timespan (2017–2022) - at least one year after completion of the last surgery included in the study. The supplementary material offers specifics of the centers CS procedure and implementation of the MIMVS procedure.

Previous line 76 about statistics has been moved to line 201 and now reads (Bold is new): 2.3 Statistics

Line 83 now reads (Bold is new): 2.2 Procedure

Line 84 now reads (Bold is new): 2.2.1 Anesthesia

Line 144 now reads (Bold is new): 2.2.2 Surgery by ..

Line 197 now reads (Bold is new): 2.2.3 Post-surgical-/ICU care.  ...

Line 200 now reads (Bold is new): 2.2.4 CS patient

Line 210 now reads (Bold is new): 2.3 Statistics

Line 222 now reads (Bold is new): 2.4 Data Acquisition. 

Comment 3: The results are presented very schematic, as opposed to the previous section, may here several paragraphs could be used.

Response 3: The authors have eliminated some bullet points in the manuscripts to make longer paragraphs:

Line 286 and 288 bullet points have been merged and now reads: 

More chord placement (57% vs 83%, p<0.001) and smaller ring sizes (34 mm vs 36mm, p<0.001)

Line 304 and 305 bullet points have been merged and now reads:

• ICU re-admissions occurred less (0 vs 3.1%, p=0.045) and hospital discharge shortened (p<0.001, median 5 vs 7).

 

Comment 4: Otherwise, the manuscript is excelent. Congratulations!

Response4: The authors Thank the reviewer

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript offers valuable insights into the challenges and outcomes associated with adopting minimally invasive mitral valve surgery (MIMVS) in a center without prior experience. The authors present a well-structured analysis of surgical outcomes, comparing MIMVS with conventional sternotomy (CS) using a robust propensity score-matching approach. Notably, the study demonstrates that while MIMVS is associated with longer surgical times, it achieves comparable in-hospital and one-year mortality outcomes to CS, along with a significantly shorter hospital stay. The discussion effectively addresses the potential benefits of MIMVS, including reduced postoperative complications, but it would be beneficial to expand on the implications of the learning curve and strategies to mitigate the risks associated with early-stage implementation. Additionally, more emphasis on patient-centered outcomes and quality of life post-surgery could strengthen the relevance of the findings. Overall, this study contributes meaningfully to the literature on MIMVS and its application in centers with limited prior experience, supporting the feasibility and safety of such programs.

Comments on the Quality of English Language

The quality of the English language in the manuscript is generally good, with clear and concise expression of ideas. The technical terminology is appropriately used, and the writing is structured logically. However, there are occasional grammatical errors and instances of awkward phrasing that could be improved for better readability. A thorough proofreading or a professional language editing service would help refine the text, enhance fluency, and ensure consistency in style.

Author Response

Comment 1: The manuscript offers valuable insights into the challenges and outcomes associated with adopting minimally invasive mitral valve surgery (MIMVS) in a center without prior experience. The authors present a well-structured analysis of surgical outcomes, comparing MIMVS with conventional sternotomy (CS) using a robust propensity score-matching approach. Notably, the study demonstrates that while MIMVS is associated with longer surgical times, it achieves comparable in-hospital and one-year mortality outcomes to CS, along with a significantly shorter hospital stay. The discussion effectively addresses the potential benefits of MIMVS, including reduced postoperative complications, but it would be beneficial to expand on the implications of the learning curve and strategies to mitigate the risks associated with early-stage implementation.

Response 1: The authors thank the reviewer for a insightful review. The authors have expanded the discussion by adding focus on the the learning curve aspect and how to potentially mitigate the risks associated with learning curve implementation.  

Line 361 now reads: However, Chikwe et al. [22] showed that low volume mitral valve centers (<50 mitral valve operations per surgeon per year) might encounter challenges in outcomes due to lack of exposure and hence low rise on the learning curve. 

Line 365 now reads: However, in the current study we found no indication that a volume of 50-60 MIMVS per year at start-up correlated with poorer outcomes and hence impeded the learning curve when adopting MIMVS

and Line 370 now reads:

The current study therefore suggest that high-quality treatment and advancement on the learning curve can be achieved by firm adherence to a strict implementation strategy.

 

Comment 2: Additionally, more emphasis on patient-centered outcomes and quality of life post-surgery could strengthen the relevance of the findings.

Response 2: Sentence emphasis patient-centered outcomes in future studies have been added in the discussion limitation section

Line 377 now reads: Furthermore, treatment success depends on a longer period of follow-up than the one year reported in the current study and preferably include data on patient centered outcomes such as quality of life post-surgery, which could strengthen the patient oriented relevance of the findings. 

 

Comment 3: Overall, this study contributes meaningfully to the literature on MIMVS and its application in centers with limited prior experience, supporting the feasibility and safety of such programs.

Response 3: The authors thank the reviewer.

Comment 4: The quality of the English language in the manuscript is generally good, with clear and concise expression of ideas. The technical terminology is appropriately used, and the writing is structured logically.

Response 4: The authors thank the reviewer.

Comment 5:  However, there are occasional grammatical errors and instances of awkward phrasing that could be improved for better readability. A thorough proofreading or a professional language editing service would help refine the text, enhance fluency, and ensure consistency in style.

Response 5: The authors have extensively proofread the manuscript and omitted errors accordingly through-out the manuscript.

Line 27 now reads: Minimizing the extent of surgical trauma through endoscopic techniques remains a cornerstone in modern surgery. in stead ofMinimizing the extent of surgical trauma through endoscopic techniques remains one of the cornerstone in modern surgery. 

Line 35 now reads Costs, decreased bleeding in stead of cost, lessen bleeding

Line 49 now reads Poorer in stead worse

Line 55 now reads treatments and/or in stead of treatment or

Line 57 now reads realizations in stead of realization

Line 62now reads: Intensive Care Unit (ICU). in stead of ICU

Line 70 now reads mild to moderate in stead of mild to moderate degree

Line 100 now reads: Standard in stead of Stanard

Line 102 now reads: blood pressure measurement in stead of pressure

Line 146 now reads: The attending anesthesiologist decided perioperative care such as intra/postoperative blood transfusion, timing of tracheal extubation and ICU management and -discharge in stead of The attending anesthesiologist decided perioperative care such as intra/postoperative blood transfusion, timing of tracheal extubation and intensive care unit management and -discharge.

Line 185 now reads Pacing in stead of Pace

Line 190 now reads The patient returned to CPB after careful TEE evaluation of the surgical result and to evaluate for possible complications in stead of The patient returned to CPB after careful TEE evaluation of the surgical result and for possible complications 

Line 212 now reads Bicaval in stead of Double

Line 214 now reads secure ring or valve position in stead of secure ring or valve

Line 233 and 264 now reads operating room in stead of OR

Line 308 now reads took in stead of was

Line 320 now reads 

• ICU re-admissions occurred less (0 vs 3.1%, p=0.045) and hospital discharge shortened (p<0.001, median 5 vs 7) after MIMVS. in stead of
• ICU re-admissions occurred less (0 vs 3.1%, p=0.045) and hospital discharge shortened (p<0.001, median 5 vs 7).

Line 334 now reads (Bold is new): The patient population presenting for mitral valve surgery in this study resembles previously published large databases[18]. 

Line 356 now reads: after in stead of in