Women with coronary artery disease who undergo coronary artery bypass grafting (CABG) are significantly less likely to receive guideline-concordant surgical interventions than their male counterparts, according to a US study presented on 30 January at the 57th Annual Meeting of The Society of Thoracic Surgeons (STS). The study, entitled ‘Sex Disparities in Coronary Artery Bypass Grafting Techniques: A Society of Thoracic Surgeons Database Analysis’ highlights an alarming disparity in cardiovascular care.
Coronary artery disease is characterised by a narrowing of the coronary arteries due to atherosclerosis (plaque buildup), resulting in restricted blood flow to the heart. It is the most common form of heart disease in the US, with a diagnosed prevalence of 12.8 million in 2020, according to GlobalData’s epidemiology database. CABG is an aggressive procedure that is usually reserved for patients with severe disease and involves the creation of a graft to bypass a blockage in the coronary artery to increase blood supply to the heart. This improves symptoms such as angina (chest pain) and reduces the risk of myocardial infarction (heart attack). However, CABG is associated with increased rates of postoperative complications and mortality in women compared to men, which prompted the researchers to investigate sex differences in surgical techniques.
The study was robust and comprised a large number of patients, which underscores the validity of the findings. A team of researchers from Duke University in Durham, North Carolina, US and the Johns Hopkins University School of Medicine in Baltimore, Maryland, US compiled records from more than 1.2 million patients who underwent first-time isolated CABG between January 2011 and June 2019, of which approximately 25% were female. The data was obtained from the STS Adult Cardiac Surgery Database (ACSD), the largest cardiac surgical database in the world, which contains records of almost all CABG procedures performed in the US. The researchers examined three different CABG techniques that are recommended in official US and EU guidelines: grafting of the left internal mammary artery (LIMA) to the left anterior descending (LAD) artery, complete revascularisation, and multiarterial grafting. Although these procedures are associated with improved short- or long-term outcomes, women were 21% less likely to undergo LIMA grafting to their LAD artery, 14% less likely to undergo complete revascularization, and 22% less likely to undergo multiarterial grafting, compared to men. Therefore, the study suggests cardiologists are less adherent to guideline recommendations when performing CABG in women, and may point towards the unconscious bias that can result in severe, even fatal, outcomes.
Study discussant Robbin G. Cohen, a cardiac surgeon from Keck School of Medicine of the University of Southern California, Los Angeles, US hypothesised that some surgeons may be more reluctant to apply the guideline-recommended techniques to women as they typically have more diffuse coronary artery disease and smaller blood vessels. However, the more severe coronary artery disease presentation in female patients referred for CABG also reflects a gender bias in care. As noted by the study authors, wider research indicates that women are more likely than men to experience delays in diagnosis and treatment referral. Consequently, by the time they are referred for surgery, they are often older and have more advanced disease and more comorbidities, which increases the risk of adverse outcomes post-surgery. Additionally, while coronary artery disease is known to manifest differently in men and women, evidence relating to various therapies and interventions relies disproportionally on male cardiovascular biology, which in turn reflects a paucity of women – both clinical trial subjects and researchers – within the R&D landscape. For example, only 17.8% of investigators currently active within coronary artery disease trials in the US are female, according to GlobalData’s clinical trials database.
While this study highlights the undertreatment of female coronary artery disease patients across the US, it also presents an opportunity to raise awareness of this issue and standardise current surgical techniques. In order to improve outcomes for female coronary artery disease patients, including post-CABG survival, the study authors advocate for surgeon education on how to overcome these disparities, and for the development of sex-specific guidelines for the diagnosis and management of coronary artery disease that incorporate important differences in disease manifestation between men and women.