Post-operative atrial fibrillation, intraoperative autologous blood salvage and transfusion in cardiac surgeryAbstract
Background and objectives Postoperative atrial fibrillation is the most common complication following cardiac surgical procedures. The objective of this study was to assess a possible association of postoperative atrial fibrillation, intraoperative autologous blood salvage, and blood transfusion.
Methods A total of 357 adult patients undergoing cardiac surgery with the use of intraoperative autologous blood salvage were included. They were divided into two groups: one with 161 patients (45%) who only received their recovered autologous blood, and another with 196 patients (55%) who additionally required the transfusion of homologous blood components. Demographic data, pre- and post-operative laboratory parameters, transfusion profiles, and clinical outcomes (mortality) were compared.
Results The number of recovered autologous blood units was not associated with an increased risk of postoperative arrhythmia (Odds ratio: 0.75; 95% CI: 0.45-1.11). Intraoperative homologous blood transfusion was associated with a significantly increased risk of death (Hazard ratio: 5.17; 95% CI 1.44-18.56). When autologous salvaged blood volume and homologous components were evaluated together, homologous transfusion was associated with higher risk of postoperative atrial fibrillation (Odds ratio: 2.51, 95% CI 1.18-5.65), whereas number of autologous units was not (OR 0.66, 95% CI 0.39-1.01). Transfusion at any time point (intraoperative, intensive care unit [ICU], or ward) was also associated with an increased risk of death (Hazard ratio: 5.15, 95% CI 1.16-22.94).
Conclusion While advanced age was significantly associated with postoperative atrial fibrillation, no association was found with intraoperative autologous blood salvage and blood transfusion.
Keywords
Atrial fibrillation; Operative blood salvage; Cardiac surgical procedures; Blood transfusion
Introduction
Postoperative atrial fibrillation (POAF) is the most common complication following cardiac surgical procedures [1]. Its incidence ranges from 20% to 50%, depending on factors such as the type of surgery, patient population, and diagnostic criteria used [2,3]. According to data from the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database, POAF occurs in 25% of patients undergoing isolated coronary artery bypass grafting (CABG), 30% of those undergoing isolated valve procedures, and 40% to 50% of those undergoing combined CABG/valve surgeries [4].
In the United Kingdom, approximately 32,000 adult patients across 35 centers undergo cardiac surgery annually, and 30% develop POAF. Even a single episode of POAF extends ICU stay by 12-24 h and hospital stay by 2-5 days [5,6], and nearly triples in-hospital mortality (from 0.5% to 3.3%) and one-year mortality (from 3.7% to 9.9%) [7,8]. POAF increases healthcare costs by approximately £10,000 ($12,500) per patient in the first postoperative year [9]. For these reasons, the prevention of POAF was identified as one of the top ten research priorities by the James Lind Alliance Cardiac Surgery Priority Setting Partnership in 2019, involving patients, caregivers, and healthcare professionals [10].
Multiple studies have confirmed that patients who develop POAF face increased risks of morbidity, mortality [11,12], and complications such as stroke, heart failure, renal dysfunction, and prolonged hospitalization [12,13]. Reducing its incidence may improve clinical outcomes, increasing interest in identifying risk factors that could enable the implementation of preventive strategies.
The pathophysiology of new-onset POAF remains poorly understood. Recent evidence supports an inflammatory mechanism in its development [14,15]. Transfusions of red blood cells (RBCs) or whole blood (WB) modulate the inflammatory response to cardiac surgery by altering various inflammatory mediators and enhancing systemic inflammation [16,17]. Currently, the most effective and safest method to reduce the need for transfusion and its potential complications is intraoperative autologous blood salvage, especially in cardiac surgeries (Class I; Level A evidence) [18]. This technique is a cornerstone of patient blood management [19]. Autologous cell salvage may improve red blood cell viability, preserve their biconcave shape, enhance oxygen delivery, and attenuate the inflammatory response to surgery [20,21].
This retrospective cohort study was designed to assess a potential association between POAF, autologous blood salvage, and transfusion as the primary outcome, and mortality risk as a secondary outcome.
Material and methods
This retrospective observational cohort study collected data from 26 hospitals in four Brazilian states, evaluating 357 adult patients who underwent cardiac surgery with intraoperative autologous blood salvage between January 2021 and December 2023.
The study was conducted in accordance with the Declaration of Helsinki (2008 revision). Due to the retrospective nature of the study and the use of anonymized data, consent was considered unnecessary.
Nearly all types of cardiac surgeries were represented: CABG, valve replacement or repair (VR), aortic aneurysm repair (AAR), the Bentall-de Bono procedure (BB), redirection of blood flow (RBF), myectomy, cardiac tumor resection, and combined procedures (e.g., CABG + VR, CABG + AAR, or VR + AAR). Preoperative and intraoperative variables (volume and number of autologous units recovered) were assessed for potential associations with an increased risk of transfusion.
Cell saver protocol
All cell salvage machines were calibrated and programmed according to a specific protocol based on patient blood volume, with bowl size and flow rates adjusted accordingly for each cycle phase. Blood was collected from skin incision through wound closure using a dual-lumen suction catheter designed for blood collection. Suction pressure was maintained below 100 mmHg to minimize hemolysis. Anticoagulation was achieved using 25,000 IU of heparin diluted in 1000 mL of 0.9% saline solution. Anticoagulant flow was adjusted based on surgical field bleeding rates, and the blood was filtered and stored in a cardiotomy reservoir. Whenever possible, residual blood from the cardiopulmonary bypass circuit was also redirected to the reservoir to maximize autologous blood salvage.
The cell saver system operated in either manual or automatic mode, with automatic mode prioritized to ensure standardized, pre-defined blood processing with minimal operator intervention. Red blood cells were washed and resuspended in 0.9% saline, resulting in a hematocrit of approximately 60%. These washed autologous red blood cells were transferred to a sterile reinfusion bag and transfused intraoperatively.
In the perioperative period, patients requiring additional blood volume beyond their own autologous blood received leukoreduced homologous red blood cell transfusions. In cases of excessive blood loss and cardiovascular instability, transfusions were administered at the discretion of the anesthesiology or intensive care team.
Statistical analysis
Data are presented as mean ((standard deviation), median (interquartile range [IQR]), or frequency (valid %) as appropriate. Comparisons between groups were performed using Student’s t-test, Mann-Whitney U test, or chi-square test, depending on data distribution and normality assessed via the Shapiro-Wilk test. Logistic regression models and Cox proportional hazards models were used to evaluate associations between variables of interest and postoperative arrhythmia and mortality, respectively. All analyses were conducted using R statistical software (R Foundation for Statistical Computing, 2024).
Results
Patients were divided into two groups: one with 161 patients (45%) who only received their recovered autologous blood, and the other with 196 patients (55%) who also required transfusion of homologous blood components (Table 1). Patients who received homologous blood were more frequently female (p-value <0.001), had lower body weight (p-value = 0.002), and exhibited lower preoperative levels of hemoglobin, hematocrit, and platelets (p-value <0.001).
Regarding autologous blood recovery, the median volume was 505 mL (1.3 units) in the group that required homologous transfusion, compared to 462 mL (1.2 units) in the group that did not require homologous components (p-value <0.001) (Table 2).
The most commonly used blood component in the operating room was packed red blood cells (PRBCs; n = 107), with a median of 2 (IQR = 1.5) units. PRBCs were also the most frequently used component in the ICU.
With respect to surgical type, 163 patients (45.7%) underwent CABG, 129 (36.1%) underwent valve surgery, and 34 (9.5%) underwent aortic aneurysm repair. Other surgical procedures were less frequent.
Autologous blood transfusion was not associated with POAF (Odds ratio [OR] = 0.75; 95% CI: 0.45-1.11). The only factor independently associated with POAF in the multivariate analysis was older age (OR 1.04; 95% CI: 1.01-1.08) (Table 3).
When autologous salvaged blood volume and homologous components were evaluated together, homologous transfusion was associated with higher risk of POAF (OR 2.51; 95% CI 1.18-5.65), whereas number of autologous units was not (OR 0.66; 95%CI 0.39-1.01). This analysis was adjusted for pre-operative hemoglobin (Table 4).
Simultaneous evaluation of homologous transfusion and autologous transfusion regarding the odds of post-operative atrial fibrillation.
Regarding mortality, intraoperative homologous blood transfusion was associated with a significantly increased risk of death (HR: 5.67; 95% CI: 1.64-19.62). This association remained consistent in the multivariate analysis (HR: 5.17; 95% CI: 1.44-18.56), adjusted for age, sex, preoperative hemoglobin, and body weight (Table 5). Transfusion at any time point (intraoperative, ICU, or ward) was also associated with an increased risk of death (HR: 5.15; 95% CI: 1.16-22.94).
Both a higher volume of autologous blood recovered and the use of homologous blood transfusion were associated with an increased risk of death. The number of autologous units recovered was associated with a higher risk of mortality (HR: 1.83; 95% CI: 1.39-2.41), as was older age (HR: 1.04; 95% CI: 1.01-1.08). Conversely, higher preoperative hemoglobin levels were associated with a reduced risk of death (HR: 0.80; 95% CI: 0.67-0.96) (Table 6). Patients who needed homologous blood transfusion had lower survival (log-rank - p-value <0.01, Figure 1).
Survival analysis stratified according to use of homologous blood products Patients who received homologous blood products (HBP) had lower survival (log-rank - p-value <0.01).
Discussion
The transfusion-related findings in this study underscore the urgent need to implement Patient Blood Management, as emphasized by the World Health Organization (WHO) in 2021. The WHO highlighted that anemia has a global prevalence, affecting billions of individuals worldwide. Preoperative anemia in surgical patients is more prevalent than in the general population and is associated with significantly increased morbidity, mortality, and hospital length of stay across most surgical procedures [22].
When comparing baseline characteristics between groups, preoperative hematocrit, hemoglobin, and platelet levels indicated that the group requiring homologous blood transfusions already presented with anemia at admission (hematocrit median = 37%; IQR: 8.755 and hemoglobin median = 12 g/dL; IQR: 3.2 g/dL; p-value <0.001). In this study, the risk-adjusted impact of preoperative hematocrit on morbidity and mortality is consistent with prior publications in cardiac surgery patients. Multiple studies have demonstrated a significant correlation between preoperative or intraoperative anemia and adverse cardiac surgical outcomes [23-25].
LaPar et al. investigated the relative contribution of preoperative hematocrit and packed red blood cell (PRBC) transfusion to postoperative outcomes following CABG. In this multi-institutional analysis of over 33,000 patient records, the key findings showed that PRBC transfusions had a greater impact than preoperative hematocrit on postoperative mortality, stroke, and renal failure [26]. Therefore, transfusion may be more of a marker of a critically ill patient than the direct cause of death.
In the present cohort, the anemic group also had significantly lower platelet counts (p-value = 0.047), which may explain the higher incidence of reported ‘increased intraoperative bleeding’ (20 patients - 10.2%), the need for homologous blood components in the operating room (158 patients - 80.6%), and the higher volume of recovered autologous red blood cells (median: 505 mL; IQR: 365.75 mL - p-value <0.001). In contrast, this complication was reported in only two patients (1.2%) in the non-transfused group.
Some authors have suggested that perioperative blood transfusions may induce systemic inflammatory changes, potentially increasing the likelihood of developing POAF in transfused patients during cardiac surgery [14,27,28]. However, the findings of this study are supported by a previous study that showed that intraoperative autologous blood transfusion was not associated with POAF (OR: 1.13; 95% CI: 0.49-2.62), and the number of autologous blood units recovered was also not associated with increased risk of POAF (OR: 0.75; 95% CI: 0.45-1.11) [29]. These results remained consistent after adjustment for age, weight, sex, and preoperative hemoglobin level.
Limitations
The main limitations of this study are its observational, non-randomized design and the relatively small patient cohort. As a multi-institutional study involving diverse surgical, anesthetic, perfusion, and intensive care teams, the results should be interpreted with caution due to the high degree of inter-team heterogeneity. Furthermore, the clinical significance and long-term implications of POAF in cardiac surgery were not evaluated.
Conclusion
The findings of this multi-institutional retrospective cohort study of cardiac surgical patients indicate no association between POAF, intraoperative autologous blood recovery, and blood transfusion. The only factor associated with POAF was advanced age. Preoperative anemia and blood transfusion independently increased the risk of postoperative morbidity and mortality. Urgent implementation of patient blood management strategies is warranted to improve surgical outcomes.
Ethical considerations
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments.
Funding
Data availability
The data that support the findings of this study are available from the corresponding author upon reasonable request.
References
-
1 Shen J., Lall S., Zheng V., Buckley P., Damiano RJ Jr, Schuessler R.B. The persistent problem of new-onset postoperative atrial fibrillation: a single-institution experience over two decades. J Thorac Cardiovasc Surg. 2011 Feb;141(2):559-70. doi: 10.1016/j.jtcvs.2010.03.011.
» https://doi.org/10.1016/j.jtcvs.2010.03.011. -
2 LaPar D.J., Speir A.M., Crosby I.K., Fonner E Jr, Brown M., Rich J.B., et al. Investigators for the Virginia Cardiac Surgery Quality Initiative. Postoperative atrial fibrillation significantly increases mortality, hospital readmission, and hospital costs. Ann Thorac Surg. 2014 Aug;98(2):527-33; discussion 533. doi: 10.1016/j.athoracsur.2014.03.039.
» https://doi.org/10.1016/j.athoracsur.2014.03.039. -
3 Bessissow A., Khan J., Devereaux P.J., Alvarez-Garcia J., Alonso-Coello P. Postoperative atrial fibrillation in non-cardiac and cardiac surgery: an overview. J Thromb Haemost. 2015 Jun;13 Suppl 1:S304-12. doi: 10.1111/jth.12974. Erratum in: J Thromb Haemost. 2015 Nov;13(11):2134. 10.1111/jth.13058.
» https://doi.org/10.1111/jth.12974. -
4 D'Agostino R.S., Jacobs J.P., Badhwar V., Fernandez F.G., Paone G., Wormuth D.W., et al. The Society of thoracic surgeons adult cardiac surgery database: 2018 update on outcomes and quality. Ann Thorac Surg. 2018 Jan;105(1):15-23. doi: 10.1016/j.athoracsur.2017.10.035.
» https://doi.org/10.1016/j.athoracsur.2017.10.035. - 5 National Institute for Cardiovascular Outcomes Research (NICOR). National adult cardiac surgery audit 2017-2020. London: NICOR; 2021.
-
6 NHS England. National Cost Collection 2020-21 [accessed 2025 April 20]. Available from: https://www.england.nhs.uk/costing-in-the-nhs/national-cost-collection/#ncc1819
» https://www.england.nhs.uk/costing-in-the-nhs/national-cost-collection/#ncc1819 -
7 Mariscalco G., Klersy C., Zanobini M., Banach M., Ferrarese S., Borsani P., Cantore C., Biglioli P., Sala A. Atrial fibrillation after isolated coronary surgery affects late survival. Circulation. 2008 Oct 14;118(16):1612-8. doi: 10.1161/CIRCULATIONAHA.108.777789. Epub 2008 Sep 29.
» https://doi.org/10.1161/CIRCULATIONAHA.108.777789. -
8 El-Chami M.F., Kilgo P., Thourani V., Lattouf O.M., Delurgio D.B., Guyton R.A., et al. New-onset atrial fibrillation predicts long-term mortality after coronary artery bypass graft. J Am Coll Cardiol. 2010 Mar 30;55(13):1370-6. doi: 10.1016/j.jacc.2009.10.058.
» https://doi.org/10.1016/j.jacc.2009.10.058. - 9 Hravnak M., Hoffman L.A., Saul M.I., Zullo T.G., Whitman G.R. Resource utilization related to atrial fibrillation after coronary artery bypass grafting. Am J Crit Care. 2002 May;11(3):228-38.
-
10 Lai F.Y., Abbasciano R.G., Tabberer B., Kumar T., Murphy G.J.; Steering Group of the James Lind Alliance Heart Surgery Priority Setting Partnership. Identifying research priorities in cardiac surgery: a report from the James Lind Alliance Priority Setting Partnership in adult heart surgery. BMJ Open. 2020 Sep 3;10(9):e038001. doi: 10.1136/bmjopen-2020-038001
» https://doi.org/10.1136/bmjopen-2020-038001 -
11 Aranki S.F., Shaw D.P., Adams D.H., Rizzo R.J., Couper G.S., VanderVliet M., et al. Predictors of atrial fibrillation after coronary artery surgery. Current trends and impact on hospital resources. Circulation. 1996 Aug 1;94(3):390-7. doi: 10.1161/01.cir.94.3.390.
» https://doi.org/10.1161/01.cir.94.3.390. -
12 Villareal R.P., Hariharan R., Liu B.C., Kar B., Lee V.V., Elayda M., et al. Postoperative atrial fibrillation and mortality after coronary artery bypass surgery. J Am Coll Cardiol. 2004 Mar 3;43(5):742-8. doi: 10.1016/j.jacc.2003.11.023.
» https://doi.org/10.1016/j.jacc.2003.11.023. - 13 Horwich P., Buth K.J., Legare J.F. New onset postoperative atrial fibrillation is associated with a long-term risk for stroke and death following cardiac surgery. J Card Surg. 2013;28(1):8-13.
-
14 Koch C.G., Li L., Van Wagoner D.R., Duncan A.I., Gillinov A.M., Blackstone E.H. Red cell transfusion is associated with an increased risk for postoperative atrial fibrillation. Ann Thorac Surg. 2006 Nov;82(5):1747-56. doi: 10.1016/j.athoracsur.2006.05.045.
» https://doi.org/10.1016/j.athoracsur.2006.05.045. -
15 Xie W., Santulli G., Reiken S.R., Yuan Q., Osborne B.W., Chen B.X., et al. Mitochondrial oxidative stress promotes atrial fibrillation. Sci Rep. 2015 Jul 14;5:11427. doi: 10.1038/srep11427.
» https://doi.org/10.1038/srep11427. -
16 Fransen E., Maessen J., Dentener M., Senden N., Buurman W. Impact of blood transfusions on inflammatory mediator release in patients undergoing cardiac surgery. Chest. 1999 Nov;116(5):1233-9. doi: 10.1378/chest.116.5.1233.
» https://doi.org/10.1378/chest.116.5.1233. - 17 Belizaire R.M., Prakash P.S., Richter J.R., Robinson B.R., Edwards M.J., Caldwell C.C., et al. Microparticles from stored red blood cells activate neutrophils and cause lung injury after hemorrhage and resuscitation. J Am Coll Surg. 2012 Apr;214(4):648-55.
- 18 Ferraris V.A., Ferraris S.P., Saha S.P., Hessel E.A. 2nd, Haan C.K., Royston B.D., et al. Perioperative blood transfusion and blood conservation in cardiac surgery: the Society of Thoracic Surgeons and the Society of Cardiovascular Anesthesiologists clinical practice guideline. Ann Thorac Surg. 2007;83(5 Suppl):S27-86.
-
19 Boer C., Meesters M.I., Milojevic M., Benedetto U., Bolliger D., von Heymann C., et al. 2017 EACTS/EACTA guidelines on patient blood management for adult cardiac surgery. J Cardiothorac Vasc Anesth. 2018 Feb;32(1):88-120. doi: 10.1053/j.jvca.2017.06.026. Epub 2017 Sep 30.
» https://doi.org/10.1053/j.jvca.2017.06.026. - 20 Ashworth A., Klein A.A. Cell salvage as part of a blood conservation strategy in anaesthesia. Br J Anaesth. 2010;105(4):401-16.
-
21 Gäbel J., Westerberg M., Bengtsson A., Jeppsson A. Cell salvage of cardiotomy suction blood improves the balance between pro- and anti-inflammatory cytokines after cardiac surgery. Eur J Cardiothorac Surg. 2013 Sep;44(3):506-11. doi: 10.1093/ejcts/ezt019. Epub 2013 Feb 12.
» https://doi.org/10.1093/ejcts/ezt019. -
22 World Health Organization. The urgent need to implement patient blood management: policy brief. Geneva: WHO; 2021 [accessed 2025 April 24]. Available from: https://apps.who.int/iris/handle/10665/346655
» https://apps.who.int/iris/handle/10665/346655 -
23 Warner M.A., Hanson A.C., Schulte P.J., Sanz J.R., Smith M.M., Kauss M.L., et al. Preoperative anemia and postoperative outcomes in cardiac surgery: a mediation analysis evaluating intraoperative transfusion exposures. Anesth Analg. 2024 Apr 1;138(4):728-37. doi: 10.1213/ANE.0000000000006765. Epub 2024 Feb 9.
» https://doi.org/10.1213/ANE.0000000000006765. -
24 Muñoz M., Gómez-Ramírez S., Kozek-Langeneker S., Shander A., Richards T., Pavía J., et al. 'Fit to fly': overcoming barriers to preoperative haemoglobin optimization in surgical patients. Br J Anaesth. 2015 Jul;115(1):15-24. doi: 10.1093/bja/aev165.
» https://doi.org/10.1093/bja/aev165. -
25 Klein A.A., Collier T.J., Brar M.S., Evans C., Hallward G., Fletcher S.N., et al. Association of Cardiothoracic Anaesthetists (ACTA). The incidence and importance of anaemia in patients undergoing cardiac surgery in the UK - the first Association of Cardiothoracic Anaesthetists national audit. Anaesthesia. 2016 Jun;71(6):627-35. doi: 10.1111/anae.13423. Epub 2016 Mar 18.
» https://doi.org/10.1111/anae.13423. -
26 LaPar D.J., Hawkins R.B., McMurry T.L., Isbell J.M., Rich J.B., Speir A.M., et al. Investigators for the Virginia Cardiac Services Quality Initiative. Preoperative anemia versus blood transfusion: which is the culprit for worse outcomes in cardiac surgery? J Thorac Cardiovasc Surg. 2018 Jul;156(1):66-74.e2. doi: 10.1016/j.jtcvs.2018.03.109. Epub 2018 Apr 4.
» https://doi.org/10.1016/j.jtcvs.2018.03.109. -
27 St-Onge S., Perrault L.P., Demers P., Boyle E.M., Gillinov A.M., Cox J., et al. Pericardial blood as a trigger for postoperative atrial fibrillation after cardiac surgery. Ann Thorac Surg. 2018 Jan;105(1):321-8. doi: 10.1016/j.athoracsur.2017.07.045. Epub 2017 Nov 24.
» https://doi.org/10.1016/j.athoracsur.2017.07.045. -
28 Zakkar M., Ascione R., James A.F., Angelini G.D., Suleiman M.S. Inflammation, oxidative stress and postoperative atrial fibrillation in cardiac surgery. Pharmacol Ther. 2015 Oct;154:13-20. doi: 10.1016/j.pharmthera.2015.06.009. Epub 2015 Jun 24.
» https://doi.org/10.1016/j.pharmthera.2015.06.009. -
29 Vlahou A., Diplaris K., Ampatzidou F., Karagounnis L., Drossos G. The role of blood transfusion in the development of atrial fibrillation after coronary artery bypass grafting. Thorac Cardiovasc Surg. 2016 Dec;64(8):688-92. doi: 10.1055/s-0036-1587699. Epub 2016 Aug 30.
» https://doi.org/10.1055/s-0036-1587699.
