Editorial Gender Disparity in CABG Outcomes: An Independent Risk Factor or Not, Women Are at a Disadvantage

Abstract

In this issue of the Journal, Sharoni E. et al. from Rabin Medical Center evaluate the impact of female gender on postoperative morbidity and mortality after coronary artery bypass grafting (CABG) surgery. The authors retrospectively analyzed 1 758 isolated first-time CABG patients operated from 2003 to 2005 and found that women had distinctly different pre-and intraoperative profiles compared with men, and also a significantly higher postoperative mortality. On propensity scoring of 359 matched pairs, and validation with the bootstrap technique, female gender was not found to be an independent risk factor of death after CABG in their study. This data is based on a single center experience and seems to contradict some of the earlier studies demonstrating that female gender is in itself an independent risk factor for mortality. Previously published data have shown that women are less likely to undergo percutaneous intervention (PCI) or CABG procedures and there is a question whether this is secondary to the perception that women have a less favorable outcome. Over the years, it appeared that women had a higher morbidity and mortality after PCI or CABG and lower success rates for CABG but they shared similar long-term outcomes to men once periprocedural risk factors and characteristics were accounted for. To date, the controversy still exists about whether differences in clinical outcomes can be attributed to female gender itself or to other associated unfavorable characteristics or factors. In the majority of the previously published studies women who underwent CABG needed more urgent or emergent operations and had a higher incidence of perioperative myocardial infarction (MI), congestive heart failure (CHF) and anemia. Women undergoing CABG were also older, had a lower body surface area (BSA), and a higher incidence of diabetes, obesity, and hypertension. These associated comorbidities are known to contribute to a significantly higher perioperative mortality following CABG. From the studies that looked at the rate of perioperative MI following CABG, it appears that the higher incidence of emergent CABG in women is secondary to more acute and unstable disease. This is supported by more recent studies suggesting that, once women present with an acute MI or once they undergo cardiac catheterization, their revascularization rate is not any different from that of their male counterparts. Furthermore, their left ventricular ejection fraction is not adversely affected by the increased urgency at presentation. Other studies have concluded that lower BSA by itself is an independent risk factor for increased mortality regardless of gender. Women generally receive fewer arterial grafts and less extensive revascularization and this has been demonstrated by many single center series in which bias in decision-making was eliminated or accounted for. This was also reproduced through database analysis and was partly explained by the difference in age between the two sexes and the greater need for emergent CABG among women. It is ...

Effect of sex on early surgical outcomes of isolated coronary artery bypass grafting

“…Some authors believe that the observed differences in postoperative outcomes between males and females can be attributed to the varied distribution of the preoperative risk factors [5] and that some of these factors may even be more important predictors for postoperative mortality and morbidity than gender alone. [30][31][32] Furthermore, in agreement with our findings, several studies have noted an increased risk for postoperative morbidities in females, including prolonged mechanical ventilation, [13,14] surgical site infection, sepsis, [14] and renal complications; [8] however, not all studies have been able to confirm this risk. [5] In addition, our data did not always correspond to that found in other studies.…”

The role of gender in coronary surgery

“…Explanations for these observations are varied; however, the risk factors themselves may be more important than gender when assessing their impact on outcome data [31][32][33].…”

Effect of Gender and Race on Operative Mortality After Isolated Coronary Artery Bypass Grafting

“…2,4,5,18,19 Other factors that have been suggested to contribute to women's increased risk for operative mortality that may have played a role in our results include their smaller native coronary diameters, independent of body size, making revascularization more technically challenging, contributing to less complete revascularization and less frequent use of left internal mammary artery grafts 20À22 ; their more extensive microvascular dysfunction, which is less effectively addressed by CABG than the epicardial disease that predominates in men 20,23 ; and their more frequent need for postoperative inotropic support and periprocedural blood transfusions, and longer lengths of hospital stay, all of which influence morbidity and complications. 24 Regarding race, our results are consistent with those of studies ranging in setting from single centers to state and national databases, which have concluded that race or ethnicity itself is not a risk factor for operative CABG mortality, 9,11 but contradictory with those of 2 large studies (440,000 to 580,000 patients) that used national STS data from the mid-1990s and concluded that blacks and nonCaucasians had significantly higher risk-adjusted operative mortality than whites (odds ratio point estimates ranged from 1.16 to 1.29). 7,8 Possible explanations for the divergence in the results of these two large studies include not only the fact that the latter used substantially older data that might not reflect current patterns of care but also that, coming from a single center, our data are not subject to the differences in hospital quality that have been shown to explain as much as 35% of the disparity in mortality between races.…”