Association Between Cardiopulmonary Bypass Time and 90-Day Post-Operative Mortality in Patients Undergoing Arch Replacement with the Frozen Elephant Trunk: A Retrospective Cohort Study
Aortic arch replacement is a complex surgical procedure that has evolved significantly since its first description in 1956. Despite advancements in surgical techniques, such as the use of moderate hypothermic circulatory arrest (MHCA) and selective ante-grade cerebral perfusion (SACP) for cerebral protection, and the deployment of the frozen elephant trunk (FET) for hemostasis of distal aortic anastomosis, early post-operative mortality remains high. Cardiopulmonary bypass (CPB) is an unavoidable component of most cardiac surgeries, and prolonged CPB time has been hypothesized to increase the risk of acute renal failure, cerebral injury, and early mortality after cardiothoracic surgery. This study aimed to investigate the relationship between CPB time and 90-day post-operative mortality in patients undergoing aortic arch surgery using the FET technique with SACP.
The study retrospectively reviewed data from 377 adult patients who underwent aortic arch surgery via FET with SACP at Beijing Anzhen Hospital from July 1, 2017, to December 31, 2018. The baseline characteristics, intra-operative data, and post-operative data were collected. Univariate and multivariate Cox regression analyses were used to determine independent predictors of 90-day post-operative mortality. The study found that the 90-day post-operative mortality rate was 13.53%, with 78.51% of the patients being men. Among the patients, 318 (84.35%) had type A aortic dissections, and 28 (7.43%) had aortic aneurysms. Emergency operations were performed in 264 (70.03%) cases. The median CPB time was 202.0 minutes (interquartile range: 176.0 to 227.0 minutes).
Multivariate Cox regression analysis revealed that CPB time was independently associated with 90-day post-operative mortality after adjusting for confounding factors. The hazard ratio for 90-day post-operative mortality increased by 21% for every 10-minute increase in CPB time (95% confidence interval: 1.15–1.27, P < 0.001). Kaplan-Meier analysis based on CPB time tertiles showed that the top tertile (median CPB time of 236.0 minutes) was associated with a reduced survival rate compared to the middle and bottom tertiles (P < 0.001). Sub-group analyses based on the complexity of the underlying disease process showed similar associations between CPB time and 90-day post-operative mortality.
The study’s findings highlight the significant impact of CPB time on early post-operative mortality in patients undergoing aortic arch surgery using the FET technique with SACP. Prolonged CPB time can lead to a complex inflammatory response, activating the coagulation and fibrinolytic systems, the complement system, and leukocytes, which release cytotoxic enzymes and inflammatory mediators. These mediators can cause parenchymal organ dysfunction, increasing the risk of post-operative multi-organ failure and infectious complications. In this study, 30 out of 51 patients who died within 90 days after surgery succumbed to multiple organ failure, accounting for 58.82% of all causes of death.
The study also emphasized the importance of recognizing the relationship between CPB time and post-operative mortality during operative procedures. Surgeons should aim to minimize CPB time as much as possible to improve patient outcomes. The study’s results were consistent with previous research, which found that prolonged CPB time was associated with increased post-operative mortality in patients undergoing various cardiac surgeries. However, the current study focused specifically on patients undergoing aortic arch surgery using the FET technique, providing more targeted insights.
Several limitations of the study were noted. First, the retrospective design and single-center data collection may limit the generalizability of the findings. Future multi-center studies are needed to validate the results. Second, the study population had heterogeneous pathological types of aortic diseases, and the surgical treatment of the aortic root varied. However, sub-group analyses were performed to explore the effects of each sub-group on 90-day post-operative mortality. Third, the possibility that longer CPB time was associated with less experienced surgeons could not be ruled out, although all surgeons in the study received standard training.
In conclusion, despite advancements in organ protection techniques, CPB time remains a significant independent risk factor for 90-day post-operative mortality in patients undergoing aortic arch surgery using the FET technique with SACP. Surgeons should be aware of this relationship and strive to minimize CPB time during operative procedures to improve patient outcomes. The study underscores the need for continued research and refinement of surgical techniques to reduce the risks associated with prolonged CPB time.
doi.org/10.1097/CM9.0000000000000443
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