Handling Extensive Mitral Annular Calcification via a Minimally Invasive Right Mini-Thoracotomy Approach

Round 1

Reviewer 1 Report

Well-written, very clear presentation. Should add value to the literature. No major edits. A few small typographic errors ("an high" should be "a high", and there is one place where the word "and" is duplicated)

Author Response

We thanks the review for the comment. We double-checked the english and the style of the manuscript and we corrected as suggested. The whole manuscript has been reviewed with extensive editing of the english.

Thank you

Author Response File: Author Response.docx

Reviewer 2 Report

I thank for the opportunity to review this manuscript concerning the surgical results of MV surgery in the setting of MAC, via minimally invasive approach.

The topic is important and the paper can contribute to scientific literature by adding the results of the mini-thoracotomy approach in such a challenging setting.

However, the manuscript needs to be further ameliorated before consideration.

Here are my suggestions:

-pls recheck authorship in the manuscript

-pls remove inclusion criteria in the abstract since they are misleading.

-66.7% for 18 patients is confusing, just state the rate. Idem in results

-7.4% for 2 patients. Same as above.

-Introduction: pls add references to support the definition of MAC as a major contraindication to minimally-invasive surgery

-Study design: pls add details regarding data collection, extraction, FU completeness, date of last FU acquisition.

-Add ERB approval protocol number

-Results: why some patients underwent CT scan with contrast agent and other without (CKD I suppose)? Which is your protocol?

-Results: MV replacement was the first surgical strategy attempted or were there any patients were MV replacement was considered after intraoperative failing of MV repair?

-Results: any case of PPM? Is it possible to add echo data at discharge?

-Results: I would really like to see a survival free from reoperation curve.

-Discussion: I would focus more on describing the rationale of your surgical approach in not doing extensive annular decalcification in case of MV replacement and your techniques for MV repair. I think this is what the reader is really interested into.

-Discussion: the predicted mortality of this cohort cannot be derived from Euroscore I (10%), even Euroscore II (5%) is not truly able to depict the complexity of this population

Author Response

We thank the reviewer for the valuable comments. We tried to address the issue raised.

Comment 1. pls recheck authorship in the manuscript. Answer 1. We double-check the authorship in the title page and we confirmed they are right.

Comment 2. pls remove inclusion criteria in the abstract since they are misleading. Answer 2. We removed the inclusion criteria from the Abstract as suggested by the reviewer.

 

Comment 3. 66.7% for 18 patients is confusing, just state the rate. Idem in results. Answer 3. We modified the Results in the abstract and the Results in the main text as suggested by the reciewer.

Comment 4. 7.4% for 2 patients. Same as above. Answer 4. We modified the Results in the abstract and the Results in the main text as suggested by the reviewer.

Comment 5. Introduction: pls add references to support the definition of MAC as a major contraindication to minimally-invasive surgery. Answer 5. We thank the reviewer for the comment. Actually, the sentence is quite misleading: MAC represents a clinical challenge and may increase the complexity of the procedure if performed through a right mini-thoracotomy, however, we can’t consider it a major contraindication to minimally invasive cardiac surgery. We changed the sentence in the abstract as follow: “MAC is considered one of the main challenges for the minimally invasive approach due to the complexity of the procedure—difficulties in passing sutures and seating the valve in the presence of heavy annulus calcifications—in a restricted operative field”.

Comment 6. Study design: pls add details regarding data collection, extraction, FU completeness, date of last FU acquisition. Answer 6. We thank the reviewer for the comment, we add other information regarding details of patients characteristics and follow-up. We added the following sentences “data regarding comorbidities, echocardiographic parameters, intra-operative variables and post-operative outcomes of patients with MV disease and MAC undergoing minimally invasive cardiac surgery from September 2018 to March 2022 were prospectively collected and retrospectively analyzed”, and “Median follow-up was 271 days, and it was 100% completed”.

Comment 7. Add ERB approval protocol number. Answer 7. We added the following sentence detail: protocol number 0095187.

Comment 8. Results: why some patients underwent CT scan with contrast agent and other without (CKD I suppose)? Which is your protocol? Answer 8. This is a retrospective study, therefore it lacks a protocol to apply to all the patients enrolled. One of the inclusion criteria was to have a pre-operative CT scan analysis used to assess the severity of the annular calcification. So, patients enrolled could have an angio-CT scan with or without cardiac gating, or a basal CT scan.

Comment 9. Results: MV replacement was the first surgical strategy attempted or were there any patients were MV replacement was considered after intraoperative failing of MV repair? Answer 9. This is an interesting issue. In this series no cases of early failure of repair were reported. Only in one case, it was required an immediate mitral prosthesis replacement for moderate leak at the post-CPB echocardiographic examination. This is reported in Table 3.

Comment 10. Results: any case of PPM? Is it possible to add echo data at discharge? Answer 10. Definitive PM implantation was reported in 3 patients (11%) and this is reported in Table 3. As reported in the Results section “residual mitral regurgitation on discharge was none to mild in all the patients”. No other echo data at discharge are available.

Comment 11. Results: I would really like to see a survival free from reoperation curve. Answer 11. This is an interesting point and definitely in further analysis on more patients and longer follow-up we will consider this suggestion. At the moment, we have only 27 patients, 1 early failure with reoperation in 1pod; and 2 reo-peration for prosthesis leak at follow-up.

Comment 12. Discussion: I would focus more on describing the rationale of your surgical approach in not doing extensive annular decalcification in case of MV replacement and your techniques for MV repair. I think this is what the reader is really interested into. Answer 12. We agree with the reviewer on the focus of the paper. We added details on the sentence of the discussion regarding our surgical techniques: “Our surgical practice in patients with MV disease and MAC is, whenever possible, to prefer repair techniques, and this is usually feasible in cases of mild to moderate MAC without leaflets involvement. In our series repair techniques were performed in six out of 27 patients (22%): all the patients received a prosthetic ring, while posterior leaflet resection and artificial chords positioning were performed in three and in two patients, respectively. In case of valve replacement the technique of choice is a partial debridement of the annular calcifications in order to be able to pass the sutures and to achieve a good seating of the prosthesis. Aggressive annulus decalcification is rarely performed. With this decision-making process we could obtained effective outcome on this high-risk population: no cases of intraoperative death, atrioventricular disruption, or circumflex coronary artery injury were reported”.

Comment 13. -Discussion: the predicted mortality of this cohort cannot be derived from Euroscore I (10%), even Euroscore II (5%) is not truly able to depict the complexity of this population. Answer 13. We completely agree with the reviewer: the complexity and the true surgical risk of these patients cannot be weighed with the standard risk score. However, to date, a proper risk score able to really consider the impact of the MAC on the risk of mortality and peri-operative morbidity is not available, therefore we decided to use the Euroscore. We added this consideration in the limitation section: “As part of limitations, this is a retrospective, single center study, and a control group of patients with MV disease and MAC undergoing surgery through standard sternotomy is not available. Moreover, the peri-operative mortality stratification was performed according to the EuroSCORE which definitely underestimate the risk related to the complexity of the surgical procedure and to the fragility of the MV anulus in these patients”.

Author Response File: Author Response.docx

Reviewer 3 Report

MICS tends to be avoided in cases of mitral annulus calcification. Therefore, this is an interesting paper demonstrating the outcome of MICS for cases of mitral valve calcification.

 

1 It would be good to mention what kind of cases converted to midline incision.

2 Also, it would be an applicable article for us surgeons if there are more clear information on what kind of things which experienced surgeons should pay attention to during surgery.

Author Response

Comment 1. MICS tends to be avoided in cases of mitral annulus calcification. Therefore, this is an interesting paper demonstrating the outcome of MICS for cases of mitral valve calcification. Answer 1. We thanks the reviewer for the supportive comment.

Comment 2. It would be good to mention what kind of cases converted to midline incision. Answer 2. We had only one case of conversion to standard sternotomy due to unfavorable anatomy of the chest and bad exposure of the ascending aorta; after aortic cross-clamp we failed to get a prompt diastolic cardiac arrest, therefore we preferred to convert to standard sternotomy in order to get a safer myocardial protection. So, we cause of conversion was not related to the management of a MV disease with MAC; however, we agree with the reviewer this is an important point and we add this comment in the result section.

Comment 3. Also, it would be an applicable article for us surgeons if there are more clear information on what kind of things which experienced surgeons should pay attention to during surgery. Answer 3. Definitely first aim of the paper is to share our tips and tricks that make our MV minimally invasive program accurate and effective also in high-risk patients such as those with MAC. First, all comers have to be screened with an angio-CT scan or angiography for the diagnosis and grading of peripheral vascular disease. This allows the surgeon to allocate the patient to the safest setting of arterial perfusion and aortic clamping. Then, when looking at patients with MV disease and MAC, we prefer repair techniques whenever possible; is cases in which MV replacement is required, the technique of choice is a partial debridement of annular calcifications in order to be able to pass the sutures and to achieve a good seating of the prosthesis. We add this comment in the conclusion section.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

I thank the authors for their replies to my comments.

I still have some questions:

-Comment 5: I cannot see changes in the manuscript. If not referenced pls modify the sentence of MAC as contraindication in both the introduction and the abstract

-Comment 8: pls add it to limitation section

-Comment 10: any case of patient-prosthesis mismatch (PPM)? Pls add to limitation that postoperave echo data are limited to MR degree

-Comment 11: pls add the exact timing of the redo operation for the patients developing periprosthetic leak

Author Response

We thank the reviewer for the valuable comments. We tried to address the issue raised.

Comment 5. I cannot see changes in the manuscript. If not referenced pls modify the sentence of MAC as contraindication in both the introduction and the abstract. Answer 5. We changed the abstract and the Introduction section with the following sentences: “to date, the preferred approach is still the standard sternotomy” in the abstract and “the preferred approach is still the standard sternotomy, and only few centers have reported experiences through a minimally invasive access” in the Introduction.

 

Comment 8: pls add it to limitation section. Answer 8. We added the following sentence in the limitation section. “Moreover, not all the patients enrolled had a pre-operativa angio-CT scan with cardiac gating”.

 

Comment 10: any case of patient-prosthesis mismatch (PPM)? Pls add to limitation that postoperave echo data are limited to MR degree. Answer 10. We thank the reviewer for the comment. We went through our echocardiographic data and extrapolated details on EOA of the mitral prosthesis of the patients at follow-up. Details regarding PPM are added in table 3.

Comment 11: pls add the exact timing of the redo operation for the patients developing periprosthetic leak. Answer 11. We added in the Results section details on the timing of the surgical procedure in the patients requiring redo surgery: “in the first post-operative day” for the early failure, and “after 14 months” for the patient with diagnosis at follow-up.

Author Response File: Author Response.docx