Early bypass graft occlusion occurred significantly more frequently in female compared to male patients after isolated coronary artery bypass graft (CABG) surgery, a single-centre analysis published in The Annals of Thoracic Surgery has shown.
Conducted by Luca Koechlin, Islam Slikhanov (both of University Hospital Basel, Basel, Switzerland) and colleagues, the analysis should stimulate research on the underlying pathophysiological mechanisms responsible for disparities in outcomes after CABG surgery, the authors say.
Recent data have demonstrated poorer outcomes in female patients following CABG, they note in their Annals paper, including more frequent graft failure at a median follow-up of one year, and a higher risk of major adverse cardiac and cerebrovascular events (MACCE) within a five-year follow-up.
Early bypass graft occlusion—a potential complication that may influence long-term outcomes after CABG—has been shown to be “substantially” underestimated when imaging is restricted to symptomatic patients, they write, whilst pilot studies evaluating bypass patency using computed tomography (CT) have shown higher occlusion rates in female patients.
All patients undergoing isolated CABG at University Hospital Basel have undergone routine CT scanning since April 2020, enabling the researchers to investigate the presence of a sex-specific difference in early bypass graft occlusion rates.
The study included a total of 589 patients who underwent isolated CABG at the institution between April 2020 and January 2025. Patients had a mean age of 67 years, and were mostly male, with 95 female patients (16%) treated over the duration of the study. Female patients were older and more often had extracardiac arteriopathy and previous cerebrovascular events, the researchers detail, noting that the majority of the demographic data were comparable between the two sexes.
Female patients received fewer distal anastomoses compared to men (3 vs. 4), more often venous grafts and less often a second arterial graft, whilst the right internal mammary artery (RIMA) was used less often in female patients (15% vs. 25%).
Graft occlusion was detected in a total of 45 (7.6%) of the patients, the researchers report, observing that this was seen significantly more often in female patients (13.7%) compared to males (6.5%). The majority of the occlusions—87%—were classed as being clinically silent, with six patients having exhibited symptoms of early in-hospital graft occlusion prompting urgent coronary angiography. Of these patients three underwent percutaneous coronary intervention (PCI) and three required redo CABG.
“The higher incidence of occlusion in female patients appears to be multifactorial and may include demographic differences, as women in our cohort undergoing CABG surgery were older and more frequently had extracardiac arteriopathy and previous cerebrovascular events,” Koechlin, Slikhanov et al document in their Annals paper. “Furthermore, women may have smaller coronary arteries, more complex coronary artery disease potentially reflected in a different SYNTAX score, and therefore undergo technically more challenging procedures; however, these factors remain speculative.”
In general, they write, the findings add to the evidence of sex-specific differences after CABG surgery, demonstrating worse outcomes for female patients.
“While most studies highlighting these differences have been retrospective and thus only hypothesis-generating, future research should focus on the underlying pathophysiological mechanisms responsible for these disparities,” they add. “Whether the sex-specific differences in occlusion rates can be reduced by adapting operative strategies or postoperative treatment remains to be evaluated in future studies.”
The authors note several limitations to their research, notably that it is a single-centre study, the small sample size, and the lack of any available data concerning patients’ SYNTAX scores.
