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Bilateral internal mammary arteries: a very important missing trick for coronary artery bypass grafting

2012; Oxford University Press; Volume: 41; Issue: 4 Linguagem: Inglês

10.1093/ejcts/ezs005

1873-734X

David P. Taggart,

Aortic Disease and Treatment Approaches

UK):If what you have shown us is correct, because this is one of the longest propensity-matched follow-ups that exists in the literature, then again, as Professor Buxton showed us, this is potentially very important.But this is also the first time I have seen a paper on bilateral internal mammary arteries which showed no difference; there was absolutely no difference in deep sternal wound infection.There are two possibilities here, either you are doing something totally different from every other group who has ever achieved this, or, alternatively, in your propensity matching you must have excluded patients who did have deep sternal wound infections.So the obvious question I am going to ask you is, of the bilateral IMA grafts you have shown us here, what percentage is that of the total population who had bilateral IMA grafts?Dr Grau: Of the total of 6,000 patients, around 1,800 of them had bilateral mammaries.From that total, we selected the group for propensity matching analysis.The overall risk of a sternal wound infection in that population was around 0.5%, so it was very low in the entire group even before our selection by propensity matching.This was shown in one of the first tables when I described the two populations; the risk of a sternal wound infection in the overall series of 6,000 cases was also very low.But the truth of the matter is that there was no difference between bilateral mammaries and the use of a single mammary, understanding that the other 4,000 patients that were not included in the single mammary SVG were likely to be people who were sick or were older and who we couldn't match by propensity matching analysis to the BIMA group.There was nobody younger.Dr Taggart: Do you use some different technique for harvesting your mammary arteries?Dr Grau: Well, I have listened to some of the questions from the previous presentation, and I have to say that what we do is we do not overuse the Bovie to cauterise anything over the sternal side of the mammary bed.We use clip, clip and cut, so there is no diathermy injury to the arcade feeding the middle of the sternum.We do not skeletonise completely, as Dr. Buxton was showing in his slides.We leave the veins attached to the in-situ mammary.Basically these are the two things that we do.We do meticulous harvesting of the mammary.Dr D. Pagano (Birmingham, UK): How many surgeons were involved in this study?Dr Grau: Four surgeons in total from 1994 to 2010.Dr Pagano: And has the rate of use of double mammary changed over time?Dr Grau: Yes, it did change.In the 1990s, I would say 1996-1997, one of the surgeons led in the use of bilateral mammaries and everybody kind of followed track after that.Dr Pagano: So there are two methodological issues that I think you need to address and recognise the potential limitations of your outstanding results.First of all, if you do a propensity score matching within a single unit, you are really tied down by confounding by indication.The second thing is that if you have four surgeons, you will have some variability in the outcomes, and that variability may be significant, and you should consider using surgeons as a random effect to account for that.