We would like to thank the authors of the Letter to the Editor for their insightful and constructive comments regarding our article entitled “Female sex as a possible factor associated with favorable long-term outcomes in off-pump coronary artery bypass surgery” [1]. We appreciate their interest in our work and agree that the interpretation of sex-related differences in long-term outcomes following off-pump coronary artery bypass (OPCAB) surgery requires considerable methodological caution. We welcome the opportunity to further discuss the strengths and limitations of our study and to clarify the intended interpretation of our findings.
First, we agree that the markedly unbalanced sex distribution represents an important limitation of our study. However, this imbalance itself reflects a relevant aspect of contemporary clinical practice. Women remain substantially less likely to undergo bilateral internal mammary artery (BIMA) grafting because of persistent concerns regarding sternal wound complications and postoperative instability. Consequently, the low proportion of female patients in our cohort mirrors real-world surgical decision-making and highlights the need for studies evaluating whether these concerns contribute to the underutilization of potentially beneficial arterial revascularization strategies in women.
Second, we fully acknowledge that Kaplan–Meier curves and the log-rank test are not designed to determine whether sex is an independent prognostic factor. Such a question would require an explanatory analysis using multivariable Cox proportional hazards regression, allowing adjustment for potential baseline differences and confounding factors. Therefore, our findings should not be interpreted as evidence that female sex independently improves long-term prognosis.
The primary objective of our analysis was descriptive rather than explanatory. We aimed to describe and compare long-term survival patterns between women and men treated with OPCAB and bilateral internal mammary artery grafting within our cohort. In this context, the Kaplan–Meier analysis demonstrated an observed difference in survival between the sexes. We believe that reporting such differences remains clinically relevant because women are historically underrepresented among patients receiving BIMA grafts and are frequently excluded from this treatment strategy due to concerns regarding sternal wound complications, mediastinal infections, and sternal instability.
At the same time, we recognize that the relatively small number of female patients substantially limits the statistical power of the analysis and increases the uncertainty surrounding the observed estimates. Consequently, the present findings should be regarded as exploratory and hypothesis-generating rather than confirmatory. We fully agree that adequately powered multivariable survival analyses, including Cox regression modelling, would be necessary to determine whether the observed association remains significant after adjustment for baseline clinical characteristics and other potential confounders.
Third, we acknowledge that the inclusion exclusively of patients undergoing OPCAB with bilateral internal mammary artery grafting limits the generalizability of our findings. Nevertheless, this selection was intentional because the principal clinical question addressed by our study concerned outcomes in a population treated with a strategy that is often avoided in women. Existing surgical practice remains cautious regarding BIMA use in female patients due to concerns about sternal complications. Importantly, our cohort did not demonstrate an excess of severe sternal wound complications among women, and the long-term survival outcomes observed in women were not inferior to those observed in men. Although these findings should be interpreted cautiously, they support the concept that female sex alone should not automatically discourage consideration of bilateral mammary artery grafting when otherwise clinically appropriate.
In summary, we agree that our findings should be interpreted as an unadjusted observation of survival differences between women and men after OPCAB with bilateral internal mammary artery grafting rather than evidence of an independent prognostic effect of female sex. The Kaplan–Meier analysis performed in our study was intended to describe survival patterns within the investigated cohort and to identify potential differences between groups. Determining whether sex independently influences long-term prognosis would require a dedicated explanatory analysis using adequately powered multivariable survival modelling with adjustment for potential confounding factors, including Cox proportional hazards regression.
Given the limited number of female patients, the results should be considered exploratory, hypothesis-generating, and suitable primarily as a basis for future investigation. Nevertheless, we believe that the clinical relevance of these findings lies in highlighting the need for further research into the role of sex in outcomes after multiple arterial revascularization and in encouraging more inclusive evaluation of BIMA grafting strategies in women.
