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CABG grafting risk thresholds differ between men and women

JAMA Cardiology
Reuters Health - 29/12/2020 - Multiple arterial grafting during coronary artery bypass surgery is associated with better outcomes among low-risk, but not high-risk, patients, and the risk cutoffs differ in men and women, according to a large observational study.

The evidence on coronary artery bypass grafting (CABG) in women "is really poor" and "we cannot extrapolate to women what we see in studies performed in a prevalently male population (women generally represent 20-25% of patients in CABG studies, much less in randomized controlled trials). It is the time to design CABG studies (including RCTs) specifically for women," Dr. Mario F. L. Gaudino told Reuters Health by email.

To examine aspects of these differences, Dr. Gaudino of Weill Cornell Medicine, in New York City and colleagues used New York State data on more than 63,000 patients who underwent CABG between 2006 and 2014. Although most (76%) were men, women generally had worse baseline characteristics, with 13.0% were deemed to be in the high-risk category compared to 6.0% of men, according to a report of the study in JAMA Cardiology.

Propensity-matching was used to analyze differences in relative outcomes between patients undergoing multiple arterial grafting (MAG) versus single arterial grafting (SAG). This yielded a total of 9512 male pairs and 1860 female pairs.

When stratified by the estimated risk of death, MAG was associated with better survival and a lower rate of a major adverse cardiac event in low-risk, but not high-risk, patients of both sexes.

More specifically, in a fully adjusted model, including the risk score, MAG was inversely associated with mortality (aHR, 0.53) but there was a positive association with female sex (aHR, 1.44) as well as with the risk score (aHR, 1.28).

Thus, say the researchers "The threshold at which MAG was not associated with improved outcome was different in the 2 sexes, suggesting that important differences in the association of MAG may exist between sexes and that data derived from studies with a predominantly male population may not be applicable to women."

Commenting by email, cardiologist Dr. L. Kristin Newby of Duke University School of Medicine, Durham, North Carolina, told Reuters Health, "It is an interesting, hypothesis-generating analysis. It would be interesting to see similar observational analysis done in randomized clinical trial datasets or other observational datasets where more granular anatomic and procedural characteristics could be considered, and further explore the effect of age and comorbidities."

"Ultimately," she concluded, MAG versus single-artery grafting seems to be "a question that is ripe for a randomized clinical trial."

SOURCE: https://bit.ly/2X4XZGZ JAMA Cardiology, online December 23, 2020.

By David Douglas

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