Scandinavian Cardiovascular Journal, 2014; 48: 69–70
EDITORIAL
Postoperative atrial fibrillation and stroke—is it time to act? Anders Ahlsson Department of Cardiothoracic and Vascular Surgery, Örebro University Hospital, Örebro, Sweden and School of Health and Medical Sciences, Örebro University, Örebro, Sweden
Postoperative atrial fibrillation (AF) affects one-third of patients undergoing cardiac surgery, and is the most common complication after the procedure. The typical form is an episode of AF with an onset at the second postoperative day, lasting one or two days, and with the patient discharged in sinus rhythm (SR). Postoperative AF belongs to the family of secondary AF, also encountered after major trauma or surgery and sepsis. It is a robust complication, responding only moderately to heavy prophylactic treatment, and there are no reliable clinical models of prediction. Some studies have shown associations with an increased morbidity and risk of stroke in the immediate postoperative period, but otherwise it has been considered a benign episode of minimal or no consequences for the future. It therefore came as a surprise when a followup of 6475 coronary artery bypass graft (CABG) patients showed that the patients with an episode of postoperative AF had an increased long-term mortality at 5 years (1). This finding was confirmed in subsequent studies, and the risk of cardiovascular death in particular was found to be increased (2,3). The hazard ratios of long-term mortality in patients with an episode of AF compared to those of patients in SR at surgery were 1.5–2.1 in these studies, which should be compared to the hazard ratio of 1.5–1.9 in (nonsurgical) patients in AF compared to patients in SR in the Framingham study (4). The basic question is, of course, whether postoperative AF is a marker of a more severe cardiovascular disease, or whether it is the tendency to develop AF in itself that constitutes the increased risk. In other words, which confounders are controlled for? In the current issue of this journal, Thorén et al. use data from the Swedish Death Registry to explore
the correlation between postoperative AF and causespecific mortality, looking into both primary and underlying causes of death (5). Their results show a significantly higher risk for cardiac death, or death related to arrhythmia, cerebrovascular disease and heart failure among patients experiencing postoperative AF at surgery compared to patients in SR, and that this effect was constant many years postoperatively. The confounders controlled for were age, hypertension, diabetes, number of prior myocardial infarctions, coronary artery anatomy and left ventricular ejection fraction. In analyzing the results of Thorén et al. together with the results of previous studies, there are some caveats. One important factor not controlled for is left ventricular diastolic dysfunction, which is correlated to AF, advanced age, and late mortality, and is thus a potential confounder in all these studies. The rate of patients receiving anticoagulation at follow-up is also unknown. One possible explanation for the observed increased risk is that postoperative AF reveals a tendency to develop AF under stress, and so postoperative AF is an indicator for later development of AF. Indeed, in one study postoperative AF patients had an eightfold increased risk of future development of AF (6), and studies have consistently shown an increased risk of cerebrovascular death among postoperative AF patients. These findings may also cast some light on the results from the Syntax and Freedom trials. These trials comparing percutaneous coronary intervention (PCI) and CABG show a consistent difference in stroke rate. In the Syntax trial, the stroke incidence at one-year follow-up was 2.2% in the CABG group compared to 0.6% in the PCI
Correspondence: Anders Ahlsson, MD, PhD, Department of Cardiothoracic and Vascular Surgery, Örebro University Hospital, SE-701 85 Örebro, Sweden. Tel: 46-19-602-10-00. Fax: 46-19-611-39-43. E-mail: [email protected] (Received 9 January 2014; revised 10 January 2014; accepted 11 January 2014) ISSN 1401-7431 print/ISSN 1651-2006 online © 2014 Informa Healthcare DOI: 10.3109/14017431.2014.883638
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group (7), while in the Freedom trial, the stroke incidence at 5 years was 5.2% in the CABG group and 2.4% in the PCI group (8). It is worth noting that the incidence of postoperative AF was not recorded in these trials. Since postoperative AF after PCI is a very rare event as far as we know, the differences in stroke rate may partly be explained by episodes of (unprotected) postoperative AF among CABG patients. Together, all these findings raise the important question: how are CABG patients treated today with regard to antithrombotic and anticoagulation therapy, and is there need for a change in patients experiencing postoperative AF? All patients undergoing CABG are offered single or dual antiplatelet therapy depending on the presence of drug-eluting stents and type of coronary artery disease (9,10). However, antiplatelet therapy offers only moderate protection against thromboembolic disease in patients with AF (11). The indication for anticoagulation in patients with an episode of postoperative AF does not essentially differ from other types of AF. Given the short duration of a typical episode of postoperative AF, warfarin is seldom prescribed at discharge [3.6% of postoperative AF patients in one study (6)]. The important message from the findings of Thorén et al. and previous researchers is that postoperative AF patients have a sustained long-term risk of cardiovascular death and especially thromboembolic cerebral complications. The risk of future development of AF, which may be asymptomatic, merits increased attention. We have reason to believe that some postoperative AF patients experience asymptomatic AF episodes at home, which are unprotected. Therefore, a randomized trial comparing, for example, one of the novel oral anticoagulants to placebo in patients with one episode of post operative AF would be of great interest. Although the numbers of patients needed in such a study would be great, the consistently higher stroke rate in CABG patients needs to be addressed. Is a Scandinavian multicentre study a possible way of moving forward?
Declaration of interest: The author report no declarations of interest. The author alone is responsible for the content and writing of the paper.
References 1. Villareal RP, Hariharan R, Liu BC, Kar B, Lee VV, Elayda M, et al. Postoperative atrial fibrillation and mortality after coronary artery bypass surgery. J Am Coll Cardiol. 2004;43:742–8. 2. Ahlsson A, Bodin L, Fengsrud E, Englund A. Patients with postoperative atrial fibrillation have a doubled cardio vascular mortality. Scand Cardiovasc J. 2009;43:330–6. 3. Mariscalco G, Klersy C, Zanobini M, Banach M, Ferrarese S, Borsani P, et al. Atrial fibrillation after isolated coronary surgery affects late survival. Circulation. 2008; 118:1612–18. 4. Benjamin EJ, Wolf PA, D’Agostino RB, Silbershatz H, Kannel WB, Levy D. Impact of atrial fibrillation on the risk of death: the Framingham Heart Study. Circulation. 1998;98:946–52. 5. Thorén E, Hellgren L, Granath F, Hörte L-G, Ståhle E. Postoperative atrial fibrillation predicts cause-specific late mortality after coronary surgery. Scand Cardiovasc J. 2014; 48:71–8. 6. Ahlsson A, Fengsrud E, Bodin L, Englund A. Postoperative atrial fibrillation in patients undergoing aortocoronary bypass surgery carries an eightfold risk of future atrial fibrillation and a doubled cardiovascular mortality. Eur J Cardiothorac Surg. 2010;37:1353–9. 7. Serruys PW, Morice MC, Kappetein AP, Colombo A, Holmes DR, Mack MJ, et al. Percutaneous coronary intervention versus coronary-artery bypass grafting for severe coronary artery disease. N Engl J Med. 2009;360:961–72. 8. Farkouh ME, Domanski M, Sleeper LA, Siami FS, Dangas G, Mack M, et al. Strategies for multivessel revascularization in patients with diabetes. N Engl J Med. 2012;367:2375–84. 9. Wijns W, Kolh P, Danchin N, Di Mario C, Falk V, Folliguet T, et al.; Task Force on Myocardial Revascularization of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS); European Association for Percutaneous Cardiovascular Interventions (EAPCI). Guidelines on myocardial revascularization. Eur Heart J. 2010;31:2501–55. 10. Cannon CP, Harrington RA, James S, Ardissino D, Becker RC, Emanuelsson H, et al. Comparison of ticagrelor with clopidogrel in patients with a planned invasive strategy for acute coronary syndromes (PLATO): a randomised double-blind study. Lancet. 2010;375:283–93. 11. Fuster V, Ryden LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, et al.; Task Force on Practice Guidelines, American College of Cardiology/American Heart Association; Committee for Practice Guidelines, European Society of Cardiology; European Heart Rhythm Association; Heart Rhythm Society. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation-executive summary: a report of the American College of Cardiology/ American Heart Association Task Force on practice guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients with Atrial Fibrillation). Eur Heart J. 2006;27:1979–2030.
Copyright of Scandinavian Cardiovascular Journal is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
EDITORIAL
Postoperative atrial fibrillation and stroke—is it time to act? Anders Ahlsson Department of Cardiothoracic and Vascular Surgery, Örebro University Hospital, Örebro, Sweden and School of Health and Medical Sciences, Örebro University, Örebro, Sweden
Postoperative atrial fibrillation (AF) affects one-third of patients undergoing cardiac surgery, and is the most common complication after the procedure. The typical form is an episode of AF with an onset at the second postoperative day, lasting one or two days, and with the patient discharged in sinus rhythm (SR). Postoperative AF belongs to the family of secondary AF, also encountered after major trauma or surgery and sepsis. It is a robust complication, responding only moderately to heavy prophylactic treatment, and there are no reliable clinical models of prediction. Some studies have shown associations with an increased morbidity and risk of stroke in the immediate postoperative period, but otherwise it has been considered a benign episode of minimal or no consequences for the future. It therefore came as a surprise when a followup of 6475 coronary artery bypass graft (CABG) patients showed that the patients with an episode of postoperative AF had an increased long-term mortality at 5 years (1). This finding was confirmed in subsequent studies, and the risk of cardiovascular death in particular was found to be increased (2,3). The hazard ratios of long-term mortality in patients with an episode of AF compared to those of patients in SR at surgery were 1.5–2.1 in these studies, which should be compared to the hazard ratio of 1.5–1.9 in (nonsurgical) patients in AF compared to patients in SR in the Framingham study (4). The basic question is, of course, whether postoperative AF is a marker of a more severe cardiovascular disease, or whether it is the tendency to develop AF in itself that constitutes the increased risk. In other words, which confounders are controlled for? In the current issue of this journal, Thorén et al. use data from the Swedish Death Registry to explore
the correlation between postoperative AF and causespecific mortality, looking into both primary and underlying causes of death (5). Their results show a significantly higher risk for cardiac death, or death related to arrhythmia, cerebrovascular disease and heart failure among patients experiencing postoperative AF at surgery compared to patients in SR, and that this effect was constant many years postoperatively. The confounders controlled for were age, hypertension, diabetes, number of prior myocardial infarctions, coronary artery anatomy and left ventricular ejection fraction. In analyzing the results of Thorén et al. together with the results of previous studies, there are some caveats. One important factor not controlled for is left ventricular diastolic dysfunction, which is correlated to AF, advanced age, and late mortality, and is thus a potential confounder in all these studies. The rate of patients receiving anticoagulation at follow-up is also unknown. One possible explanation for the observed increased risk is that postoperative AF reveals a tendency to develop AF under stress, and so postoperative AF is an indicator for later development of AF. Indeed, in one study postoperative AF patients had an eightfold increased risk of future development of AF (6), and studies have consistently shown an increased risk of cerebrovascular death among postoperative AF patients. These findings may also cast some light on the results from the Syntax and Freedom trials. These trials comparing percutaneous coronary intervention (PCI) and CABG show a consistent difference in stroke rate. In the Syntax trial, the stroke incidence at one-year follow-up was 2.2% in the CABG group compared to 0.6% in the PCI
Correspondence: Anders Ahlsson, MD, PhD, Department of Cardiothoracic and Vascular Surgery, Örebro University Hospital, SE-701 85 Örebro, Sweden. Tel: 46-19-602-10-00. Fax: 46-19-611-39-43. E-mail: [email protected] (Received 9 January 2014; revised 10 January 2014; accepted 11 January 2014) ISSN 1401-7431 print/ISSN 1651-2006 online © 2014 Informa Healthcare DOI: 10.3109/14017431.2014.883638
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A. Ahlsson
group (7), while in the Freedom trial, the stroke incidence at 5 years was 5.2% in the CABG group and 2.4% in the PCI group (8). It is worth noting that the incidence of postoperative AF was not recorded in these trials. Since postoperative AF after PCI is a very rare event as far as we know, the differences in stroke rate may partly be explained by episodes of (unprotected) postoperative AF among CABG patients. Together, all these findings raise the important question: how are CABG patients treated today with regard to antithrombotic and anticoagulation therapy, and is there need for a change in patients experiencing postoperative AF? All patients undergoing CABG are offered single or dual antiplatelet therapy depending on the presence of drug-eluting stents and type of coronary artery disease (9,10). However, antiplatelet therapy offers only moderate protection against thromboembolic disease in patients with AF (11). The indication for anticoagulation in patients with an episode of postoperative AF does not essentially differ from other types of AF. Given the short duration of a typical episode of postoperative AF, warfarin is seldom prescribed at discharge [3.6% of postoperative AF patients in one study (6)]. The important message from the findings of Thorén et al. and previous researchers is that postoperative AF patients have a sustained long-term risk of cardiovascular death and especially thromboembolic cerebral complications. The risk of future development of AF, which may be asymptomatic, merits increased attention. We have reason to believe that some postoperative AF patients experience asymptomatic AF episodes at home, which are unprotected. Therefore, a randomized trial comparing, for example, one of the novel oral anticoagulants to placebo in patients with one episode of post operative AF would be of great interest. Although the numbers of patients needed in such a study would be great, the consistently higher stroke rate in CABG patients needs to be addressed. Is a Scandinavian multicentre study a possible way of moving forward?
Declaration of interest: The author report no declarations of interest. The author alone is responsible for the content and writing of the paper.
References 1. Villareal RP, Hariharan R, Liu BC, Kar B, Lee VV, Elayda M, et al. Postoperative atrial fibrillation and mortality after coronary artery bypass surgery. J Am Coll Cardiol. 2004;43:742–8. 2. Ahlsson A, Bodin L, Fengsrud E, Englund A. Patients with postoperative atrial fibrillation have a doubled cardio vascular mortality. Scand Cardiovasc J. 2009;43:330–6. 3. Mariscalco G, Klersy C, Zanobini M, Banach M, Ferrarese S, Borsani P, et al. Atrial fibrillation after isolated coronary surgery affects late survival. Circulation. 2008; 118:1612–18. 4. Benjamin EJ, Wolf PA, D’Agostino RB, Silbershatz H, Kannel WB, Levy D. Impact of atrial fibrillation on the risk of death: the Framingham Heart Study. Circulation. 1998;98:946–52. 5. Thorén E, Hellgren L, Granath F, Hörte L-G, Ståhle E. Postoperative atrial fibrillation predicts cause-specific late mortality after coronary surgery. Scand Cardiovasc J. 2014; 48:71–8. 6. Ahlsson A, Fengsrud E, Bodin L, Englund A. Postoperative atrial fibrillation in patients undergoing aortocoronary bypass surgery carries an eightfold risk of future atrial fibrillation and a doubled cardiovascular mortality. Eur J Cardiothorac Surg. 2010;37:1353–9. 7. Serruys PW, Morice MC, Kappetein AP, Colombo A, Holmes DR, Mack MJ, et al. Percutaneous coronary intervention versus coronary-artery bypass grafting for severe coronary artery disease. N Engl J Med. 2009;360:961–72. 8. Farkouh ME, Domanski M, Sleeper LA, Siami FS, Dangas G, Mack M, et al. Strategies for multivessel revascularization in patients with diabetes. N Engl J Med. 2012;367:2375–84. 9. Wijns W, Kolh P, Danchin N, Di Mario C, Falk V, Folliguet T, et al.; Task Force on Myocardial Revascularization of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS); European Association for Percutaneous Cardiovascular Interventions (EAPCI). Guidelines on myocardial revascularization. Eur Heart J. 2010;31:2501–55. 10. Cannon CP, Harrington RA, James S, Ardissino D, Becker RC, Emanuelsson H, et al. Comparison of ticagrelor with clopidogrel in patients with a planned invasive strategy for acute coronary syndromes (PLATO): a randomised double-blind study. Lancet. 2010;375:283–93. 11. Fuster V, Ryden LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, et al.; Task Force on Practice Guidelines, American College of Cardiology/American Heart Association; Committee for Practice Guidelines, European Society of Cardiology; European Heart Rhythm Association; Heart Rhythm Society. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation-executive summary: a report of the American College of Cardiology/ American Heart Association Task Force on practice guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients with Atrial Fibrillation). Eur Heart J. 2006;27:1979–2030.
Copyright of Scandinavian Cardiovascular Journal is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
