Gender differences in long-term survival after coronary artery bypass surgery is womens cardiovascular health at risk?
Authors: Sousa I , Diaz S , Cerqueira R , Ferreira A F , Amorim M J , Pinho P , Lourenco A P , Barros A S , Leite-Moreira A , Saraiva F 
Published: October 2024

Abstract

Introduction
Cardiovascular healthcare for women tends to be influenced by various factors. This patient group is generally associated with a worse prognosis following coronary artery bypass surgery (CABG).

Aims
To assess the impact of gender on long-term survival after CABG and the potential effect of age on this association; to compare the survival of these patients with the expected survival of the general national population, and to compare immediate postoperative outcomes between genders.

Methods
Longitudinal, retrospective, single center study, involving consecutive patients who underwent isolated primary CABG between 2004 and 2014. Exclusion criteria included emergency/salvage surgeries or the use of extracorporeal circulation without aortic clamping. Included patients were categorized into age subgroups: ≤60, 60-70, and ≥70 years. All-cause mortality was assessed in February 2023, and a time-to-event analysis was performed using Kaplan-Meier curves, Log-Rank tests, and multivariable Cox regressions. To compare expected mortality (matched for sex and age with the general population) with observed mortality in the patient cohort, survival tables for the years 2004-2022 were consulted. Kaplan-Meier curves for the reference population, stratified by gender, were constructed and compared to the surgical cohort using one-sample Log-Rank tests with specific software. Standardized mortality ratios (SMR) were estimated. The mean follow-up time was 11 years, with a maximum of 19 years.

Results
From 3978 patients included patient’s, 21% were women (W). W were older (mean age 67±9 vs. 63±10 years, p&lt;0.001) and had a higher prevalence of cardiovascular risk factors and severe chronic kidney disease compared to men (M). M more frequently had peripheral arterial disease and smoking habits. Although three-vessel disease was similar between sexes (p=0.111), W were less frequently implanted with ≥3 grafts (p&lt;0.001). At 5,10 and 15 years of follow-up, cumulative survival for MvsW was 89%vs88%, 73%vs68%, and 57%vs46%, respectively (Log-rank test p&lt;0.001). After stratification by age, Log-Rank tests showed no differences between sexes. Multivariable adjustment did not identify gender as an independent predictor of long-term survival in any age subgroup. However, a time-stratified analysis at 10 years of follow-up in the ≥70 years subgroup showed that W had a higher risk than M after 10 years of follow-up (HR:0.7[0.5-0.9],p=0.03). Comparing with the survival of the Portuguese population, CABG allowed M to equalize the risk of mortality to what was expected (SMR =1.1;95%CI:0.9-1.1), but W showed a higher risk of mortality after CABG than W in the reference population (SMR =1.6,95%CI:1.3-1.8).

Conclusion
Women undergoing isolated primary CABG at an age &gt;70 years, with longest periods follow-up, exhibited poorer long-term survival than men of the same age.Women demonstrated inferior survival outcomes compared to the general population.