Predicting Postoperative Atrial Fibrillation: The Search Continues

Abstract

Atrial fibrillation (AF) has an incredibly large burden on the American health system, with approximately 454,000 annual hospital admissions as the primary diagnosis.1Benjamin EJ Muntner P Alonso A et al.Heart disease and stroke statistics-2019 update: A report from the American Heart Association.Circulation. 2019; 139: e56-528Crossref PubMed Scopus (4477) Google Scholar Unfortunately, AF is not a benign entity, with a reported underlying primary cause of death in 26,535 people in 2019, according to the Centers for Disease Control and Prevention.2Centers for Disease Control and Prevention. About multiple cause of death, 1999-2020. Available at: https://wonder.cdc.gov/mcd-icd10.html. Accessed June 2, 2022.Google Scholar AF is the cause of 1 in 7 strokes,3Society. Heart Rhythm, Complications from atrial fibrillation (2019). https://www.hrsonline.org/publications/heart-rhythm-o2.Google Scholar and increases the risk of ischemic stroke 5-fold.4Virani SS Alonso A Aparicio HJ et al.Heart disease and stroke statistics-2021 update: A report from the American Heart Association.Circulation. 2021; 143: e254-e743Crossref PubMed Scopus (1593) Google Scholar These statistics are alarming when it is considered that the incidence of postoperative atrial fibrillation (POAF) has been reported to be as high as 65% after cardiac surgery.5Maisel WH Rawn JD Stevenson WG. Atrial fibrillation after cardiac surgery.Ann Intern Med. 2001; 135: 1061-1073Crossref PubMed Scopus (562) Google Scholar The presumptive conclusion that can be drawn here, that there is an association between postoperative atrial fibrillation after cardiac surgery and increased mortality, hospital costs, and readmission rates, has been proven in multiple studies.6LaPar DJ Speir AM Crosby IK et al.Postoperative atrial fibrillation significantly increases mortality, hospital readmission, and hospital costs.Ann Thorac Surg. 2014; 98: 527-533Abstract Full Text Full Text PDF PubMed Scopus (159) Google Scholar,7Villareal RP Hariharan R Liu BC et al.Postoperative atrial fibrillation and mortality after coronary artery bypass surgery.J Am Coll Cardiol. 2004; 43: 742-748Crossref PubMed Scopus (502) Google ScholarWe have long needed clear predictive scoring systems for POAF. In 2001, the CHADS₂ score (congestive heart failure [CHF], hypertension [HTN], age ≥75 years, diabetes mellitus [DM], stroke) was developed to more accurately predict the risk of stroke in patients with nonrheumatic AF.8Gage BF Waterman AD Shannon W et al.Validation of clinical classification schemes for predicting stroke: Results from the National Registry of Atrial Fibrillation.JAMA. 2001; 285: 2864-2870Crossref PubMed Scopus (4124) Google Scholar Despite its simplicity, the CHADS₂ scoring system failed in its accuracy and has been widely criticized for its lack of inclusion of common stroke risk factors. This consequently resulted in a more inclusive scoring system, the CHA₂DS₂-VASc score, with the addition of the following independent stroke risk factors: female sex, age >65 years, and vascular disease (peripheral arterial disease, aortic atherosclerosis, and coronary artery disease [CAD]). The CHA₂DS₂-VASc (CHF, HTN, Age [>65 = 1 point, ≥75 = 2 points], DM, stroke and/or transient ischemic attack [2 points], vascular disease) score, like its predecessor, was developed to determine the 1-year risk of thromboembolic events in nonanticoagulated patients with nonvalvular AF. Interestingly, it has been demonstrated that many of the components of this score are associated with the development of structural heart disease and POAF,9Kashani RG Sareh S Genovese B et al.Predicting postoperative atrial fibrillation using CHA2DS2-VASc scores.J Surg Res. 2015; 198: 267-272Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar and later validated with relatively good performance in predicting POAF.10Chen YL Zeng M Liu Y et al.CHA2DS2-VASc score for identifying patients at high risk of postoperative atrial fibrillation after cardiac surgery: A meta-analysis.Ann Thorac Surg. 2020; 109: 1210-1216Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar The C₂HEST score (C₂, CAD/ and/or chronic obstructive pulmonary disease [COPD] [1 point each]; H, HTN; E, elderly age [age ≥75 years, 2 points]; S, systolic heart failure [2 points]; T, thyroid disease [hyperthyroidism]) also was developed to predict the incidence of AF, and a second iteration with age-stratified criterion has yielded the mC2HEST score with increased predictive accuracy.11Li YG Bai J Zhou G et al.Refining age stratum of the C2HEST score for predicting incident atrial fibrillation in a hospital-based Chinese population.Eur J Intern Med. 2021; 90: 37-42Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar In the busy and seemingly chaotic practice of present-day clinical medicine, the need for useful and easy-to-remember tools for risk-stratifying patients is desirable. Each of the above scoring systems has much overlap and similarity. This created a need for a comparative study to assess the discriminative ability of these scoring tools. Feilberg Rasmussen et al12Rasmussen LF, Andreasen JJ, Lundbye-Christensen S, et al. Using the C2HEST score for predicting postoperative atrial fibrillation after cardiac surgery: A report from the Western Denmark Heart Registry, the Danish National Patient Registry, and the Danish National Prescription Registry. J Cardiothorac Vasc Anesth 2022;36:3730–8.Google Scholar set forth with the objective of testing the performance of the C₂HEST score to predict POAF in patients undergoing cardiac surgery in comparison to CHADS₂, CHA₂DS₂-VASc, and mC₂HEST scores. This was a registry-based study in Denmark inclusive of 3 databases—the Western Denmark Heart Registry, National Patient Registry, and Danish National Prescription Registry. Danish citizens are given a unique personal identification number at birth or upon immigration, which allows these registries to be fairly accurate. In fact, they have been studied and validated in their degree of completeness.13Rasmussen LA Botker HE Jensen LO et al.Quality assurance of the Western Denmark Heart Registry, a population-based healthcare register.Dan Med J. 2017; 64: A5414PubMed Google Scholar, 14Munkholm SB Jakobsen CJ Mortensen PE et al.Validation of post-operative atrial fibrillation in the Western Denmark Heart Registry.Dan Med J. 2015; 62: A5162PubMed Google Scholar, 15Kildemoes HW Sorensen HT Hallas J. The Danish National Prescription Registry.Scand J Public Health. 2011; 39: 38-41Crossref PubMed Scopus (1480) Google ScholarThe study population included all patients ≥18 years of age who underwent cardiac surgery in Denmark from January 1, 2010 to December 31, 2018. If multiple cardiac surgeries were performed, only the first procedure was included. The exclusion criteria were preoperative AF, history of AF, or cardiac transplant. Variables collected from registries included CAD, COPD, HTN, CHF, peripheral vascular disease, stroke or transient ischemic attack, and DM. POAF was defined in the study as new-onset AF recorded by continuous telemetry and/or standard 12-lead electrocardiogram during the postoperative period until discharge. Of note, POAF or incident AF that occurred after transfer to other specialist wards or hospitals was not recorded in the Western Denmark Heart Registry and, therefore, not included.In total, 16,762 cardiac surgeries were performed in this time period; however, 14,279 patients were included in the study after the application of the above exclusion criteria. Of this population, 30.1% (4,298 patients) experienced POAF, 75.9% of whom were male patients. In the POAF group, there was noted to be a higher prevalence of HTN, COPD, and thyroid disease. There was also a higher mean C₂HEST score in the POAF group when compared to the group without POAF (3.1 ± 1.5 v 2.75 ± 1.49, respectively; p < 0.001). This trend was similar in the CHADS₂ and CHA₂DS₂-VASc scores as well. The variable found to be most associated with the greatest risk of POAF was age ≥65 years. As previously mentioned, COPD, HTN, and thyroid disease were independently related with POAF (odds ratio [OR] 1.25 [1.12-1.40], OR 1.29 [1.13-1.47], and OR 1.55 [1.23-1.94], respectively). It was found there was no difference in the predictive capabilities of the C₂HEST, CHADS₂, and CHA₂DS₂-VASc scores in stratified risk groups after calculating the area under the curve.Ultimately, Feilberg Rasmussen et al12Rasmussen LF, Andreasen JJ, Lundbye-Christensen S, et al. Using the C2HEST score for predicting postoperative atrial fibrillation after cardiac surgery: A report from the Western Denmark Heart Registry, the Danish National Patient Registry, and the Danish National Prescription Registry. J Cardiothorac Vasc Anesth 2022;36:3730–8.Google Scholar concluded that an elevated C₂HEST score was associated with an increased risk of POAF; however, there is limited value in utilizing it as an initial screening tool to identify patients at high risk of POAF. Additionally, its comparative predictive value is similar to that of CHADS₂ and CHA₂DS₂-VASc scores. As was pointed out in their discussion, the early detection and treatment of POAF are vital to preventing postoperative morbidity and mortality. Unfortunately, this study was unable to demonstrate any significant difference in the various risk models discussed above. There have been a plethora of data to support the early identification of incident AF, but extrapolating these data into the POAF realm appears to be inadequate at best.It previously been demonstrated that the length of cardiopulmonary bypass and the type of cardiac procedure performed do have an influence on the incidence of POAF.16Zhang W Liu W Chew ST et al.A clinical prediction model for postcardiac surgery atrial fibrillation in an Asian population.Anesth Analg. 2016; 123: 283-289Crossref PubMed Scopus (15) Google Scholar,17Woldendorp K Farag J Khadra S et al.Postoperative atrial fibrillation after cardiac surgery: A meta-analysis.Ann Thorac Surg. 2021; 112: 2084-2093Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar These variables were not considered in the above scoring systems and could be representative of the shortcomings of these predictive models. There is also an obvious limitation to a registry-based study; however, the data in the registries were relatively robust, as outlined in the study.To conclude, we believe that the true significance of this study was demonstrating that these predictive models (C₂HEST, mC₂HEST, CHADS₂, CHA₂DS₂-VASc) are similar in their limited ability to predict POAF. It is highly unfortunate that they do not translate accurately into the perioperative setting; however, this did demonstrate the need for further investigation into POAF predictive modeling. Atrial fibrillation (AF) has an incredibly large burden on the American health system, with approximately 454,000 annual hospital admissions as the primary diagnosis.1Benjamin EJ Muntner P Alonso A et al.Heart disease and stroke statistics-2019 update: A report from the American Heart Association.Circulation. 2019; 139: e56-528Crossref PubMed Scopus (4477) Google Scholar Unfortunately, AF is not a benign entity, with a reported underlying primary cause of death in 26,535 people in 2019, according to the Centers for Disease Control and Prevention.2Centers for Disease Control and Prevention. About multiple cause of death, 1999-2020. Available at: https://wonder.cdc.gov/mcd-icd10.html. Accessed June 2, 2022.Google Scholar AF is the cause of 1 in 7 strokes,3Society. Heart Rhythm, Complications from atrial fibrillation (2019). https://www.hrsonline.org/publications/heart-rhythm-o2.Google Scholar and increases the risk of ischemic stroke 5-fold.4Virani SS Alonso A Aparicio HJ et al.Heart disease and stroke statistics-2021 update: A report from the American Heart Association.Circulation. 2021; 143: e254-e743Crossref PubMed Scopus (1593) Google Scholar These statistics are alarming when it is considered that the incidence of postoperative atrial fibrillation (POAF) has been reported to be as high as 65% after cardiac surgery.5Maisel WH Rawn JD Stevenson WG. Atrial fibrillation after cardiac surgery.Ann Intern Med. 2001; 135: 1061-1073Crossref PubMed Scopus (562) Google Scholar The presumptive conclusion that can be drawn here, that there is an association between postoperative atrial fibrillation after cardiac surgery and increased mortality, hospital costs, and readmission rates, has been proven in multiple studies.6LaPar DJ Speir AM Crosby IK et al.Postoperative atrial fibrillation significantly increases mortality, hospital readmission, and hospital costs.Ann Thorac Surg. 2014; 98: 527-533Abstract Full Text Full Text PDF PubMed Scopus (159) Google Scholar,7Villareal RP Hariharan R Liu BC et al.Postoperative atrial fibrillation and mortality after coronary artery bypass surgery.J Am Coll Cardiol. 2004; 43: 742-748Crossref PubMed Scopus (502) Google Scholar We have long needed clear predictive scoring systems for POAF. In 2001, the CHADS₂ score (congestive heart failure [CHF], hypertension [HTN], age ≥75 years, diabetes mellitus [DM], stroke) was developed to more accurately predict the risk of stroke in patients with nonrheumatic AF.8Gage BF Waterman AD Shannon W et al.Validation of clinical classification schemes for predicting stroke: Results from the National Registry of Atrial Fibrillation.JAMA. 2001; 285: 2864-2870Crossref PubMed Scopus (4124) Google Scholar Despite its simplicity, the CHADS₂ scoring system failed in its accuracy and has been widely criticized for its lack of inclusion of common stroke risk factors. This consequently resulted in a more inclusive scoring system, the CHA₂DS₂-VASc score, with the addition of the following independent stroke risk factors: female sex, age >65 years, and vascular disease (peripheral arterial disease, aortic atherosclerosis, and coronary artery disease [CAD]). The CHA₂DS₂-VASc (CHF, HTN, Age [>65 = 1 point, ≥75 = 2 points], DM, stroke and/or transient ischemic attack [2 points], vascular disease) score, like its predecessor, was developed to determine the 1-year risk of thromboembolic events in nonanticoagulated patients with nonvalvular AF. Interestingly, it has been demonstrated that many of the components of this score are associated with the development of structural heart disease and POAF,9Kashani RG Sareh S Genovese B et al.Predicting postoperative atrial fibrillation using CHA2DS2-VASc scores.J Surg Res. 2015; 198: 267-272Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar and later validated with relatively good performance in predicting POAF.10Chen YL Zeng M Liu Y et al.CHA2DS2-VASc score for identifying patients at high risk of postoperative atrial fibrillation after cardiac surgery: A meta-analysis.Ann Thorac Surg. 2020; 109: 1210-1216Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar The C₂HEST score (C₂, CAD/ and/or chronic obstructive pulmonary disease [COPD] [1 point each]; H, HTN; E, elderly age [age ≥75 years, 2 points]; S, systolic heart failure [2 points]; T, thyroid disease [hyperthyroidism]) also was developed to predict the incidence of AF, and a second iteration with age-stratified criterion has yielded the mC2HEST score with increased predictive accuracy.11Li YG Bai J Zhou G et al.Refining age stratum of the C2HEST score for predicting incident atrial fibrillation in a hospital-based Chinese population.Eur J Intern Med. 2021; 90: 37-42Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar In the busy and seemingly chaotic practice of present-day clinical medicine, the need for useful and easy-to-remember tools for risk-stratifying patients is desirable. Each of the above scoring systems has much overlap and similarity. This created a need for a comparative study to assess the discriminative ability of these scoring tools. Feilberg Rasmussen et al12Rasmussen LF, Andreasen JJ, Lundbye-Christensen S, et al. Using the C2HEST score for predicting postoperative atrial fibrillation after cardiac surgery: A report from the Western Denmark Heart Registry, the Danish National Patient Registry, and the Danish National Prescription Registry. J Cardiothorac Vasc Anesth 2022;36:3730–8.Google Scholar set forth with the objective of testing the performance of the C₂HEST score to predict POAF in patients undergoing cardiac surgery in comparison to CHADS₂, CHA₂DS₂-VASc, and mC₂HEST scores. This was a registry-based study in Denmark inclusive of 3 databases—the Western Denmark Heart Registry, National Patient Registry, and Danish National Prescription Registry. Danish citizens are given a unique personal identification number at birth or upon immigration, which allows these registries to be fairly accurate. In fact, they have been studied and validated in their degree of completeness.13Rasmussen LA Botker HE Jensen LO et al.Quality assurance of the Western Denmark Heart Registry, a population-based healthcare register.Dan Med J. 2017; 64: A5414PubMed Google Scholar, 14Munkholm SB Jakobsen CJ Mortensen PE et al.Validation of post-operative atrial fibrillation in the Western Denmark Heart Registry.Dan Med J. 2015; 62: A5162PubMed Google Scholar, 15Kildemoes HW Sorensen HT Hallas J. The Danish National Prescription Registry.Scand J Public Health. 2011; 39: 38-41Crossref PubMed Scopus (1480) Google Scholar The study population included all patients ≥18 years of age who underwent cardiac surgery in Denmark from January 1, 2010 to December 31, 2018. If multiple cardiac surgeries were performed, only the first procedure was included. The exclusion criteria were preoperative AF, history of AF, or cardiac transplant. Variables collected from registries included CAD, COPD, HTN, CHF, peripheral vascular disease, stroke or transient ischemic attack, and DM. POAF was defined in the study as new-onset AF recorded by continuous telemetry and/or standard 12-lead electrocardiogram during the postoperative period until discharge. Of note, POAF or incident AF that occurred after transfer to other specialist wards or hospitals was not recorded in the Western Denmark Heart Registry and, therefore, not included. In total, 16,762 cardiac surgeries were performed in this time period; however, 14,279 patients were included in the study after the application of the above exclusion criteria. Of this population, 30.1% (4,298 patients) experienced POAF, 75.9% of whom were male patients. In the POAF group, there was noted to be a higher prevalence of HTN, COPD, and thyroid disease. There was also a higher mean C₂HEST score in the POAF group when compared to the group without POAF (3.1 ± 1.5 v 2.75 ± 1.49, respectively; p < 0.001). This trend was similar in the CHADS₂ and CHA₂DS₂-VASc scores as well. The variable found to be most associated with the greatest risk of POAF was age ≥65 years. As previously mentioned, COPD, HTN, and thyroid disease were independently related with POAF (odds ratio [OR] 1.25 [1.12-1.40], OR 1.29 [1.13-1.47], and OR 1.55 [1.23-1.94], respectively). It was found there was no difference in the predictive capabilities of the C₂HEST, CHADS₂, and CHA₂DS₂-VASc scores in stratified risk groups after calculating the area under the curve. Ultimately, Feilberg Rasmussen et al12Rasmussen LF, Andreasen JJ, Lundbye-Christensen S, et al. Using the C2HEST score for predicting postoperative atrial fibrillation after cardiac surgery: A report from the Western Denmark Heart Registry, the Danish National Patient Registry, and the Danish National Prescription Registry. J Cardiothorac Vasc Anesth 2022;36:3730–8.Google Scholar concluded that an elevated C₂HEST score was associated with an increased risk of POAF; however, there is limited value in utilizing it as an initial screening tool to identify patients at high risk of POAF. Additionally, its comparative predictive value is similar to that of CHADS₂ and CHA₂DS₂-VASc scores. As was pointed out in their discussion, the early detection and treatment of POAF are vital to preventing postoperative morbidity and mortality. Unfortunately, this study was unable to demonstrate any significant difference in the various risk models discussed above. There have been a plethora of data to support the early identification of incident AF, but extrapolating these data into the POAF realm appears to be inadequate at best. It previously been demonstrated that the length of cardiopulmonary bypass and the type of cardiac procedure performed do have an influence on the incidence of POAF.16Zhang W Liu W Chew ST et al.A clinical prediction model for postcardiac surgery atrial fibrillation in an Asian population.Anesth Analg. 2016; 123: 283-289Crossref PubMed Scopus (15) Google Scholar,17Woldendorp K Farag J Khadra S et al.Postoperative atrial fibrillation after cardiac surgery: A meta-analysis.Ann Thorac Surg. 2021; 112: 2084-2093Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar These variables were not considered in the above scoring systems and could be representative of the shortcomings of these predictive models. There is also an obvious limitation to a registry-based study; however, the data in the registries were relatively robust, as outlined in the study. To conclude, we believe that the true significance of this study was demonstrating that these predictive models (C₂HEST, mC₂HEST, CHADS₂, CHA₂DS₂-VASc) are similar in their limited ability to predict POAF. It is highly unfortunate that they do not translate accurately into the perioperative setting; however, this did demonstrate the need for further investigation into POAF predictive modeling. None. Using the C2HEST Score for Predicting Postoperative Atrial Fibrillation After Cardiac Surgery: A Report From the Western Denmark Heart Registry, the Danish National Patient Registry, and the Danish National Prescription RegistryJournal of Cardiothoracic and Vascular AnesthesiaVol. 36Issue 10PreviewNew-onset postoperative atrial fibrillation (POAF) is a common complication after cardiac surgery. A targeted approach is necessary for prophylactic handling of the complication. The authors tested the performance of the C2HEST score to predict POAF in patients undergoing cardiac surgery. Full-Text PDF Open Access