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Canadian Cardiovascular Society 2014 Algorithm for Anticoagulation Therapy in Atrial Fibrillation Debated
Canadian Journal of Cardiology 31 (2015) 1e2
Journal News and Commentary
Canadian Cardiovascular Society 2014 Algorithm for Anticoagulation Therapy in Atrial Fibrillation Debated Stanley Nattel, MD Departments of Medicine, Montreal Heart Institute and Universite de Montre al, Montreal, Quebec, Canada
Atrial fibrillation (AF) is a major risk factor for ischemic stroke.1 Although AF-related strokes can be prevented by oral anticoagulation, because of an increased bleeding risk anticoagulation therapy is reserved for patients with increased stroke risk. A variety of systems have been developed over the years to identify appropriate patients for therapy.2 Risk factors are used extensively to determine which AF patients stand to benefit from oral anticoagulation. The most widely used algorithm at present is the Congestive Heart Failure, Hypertension, Age (75 years), Diabetes, Stroke/Transient Ischemic Attack, Vascular Disease, Age (65-74 years), Sex (Female) (CHA2DS2-VASc) system, endorsed by the European Society of Cardiology (ESC) and other agencies, which attributes 1 point each for age 65, congestive heart failure (including left ventricular dysfunction), hypertension, diabetes, vascular disease (myocardial infarction, peripheral arterial disease, complex aortic plaque), and female sex, while 2 points each are attributed to previous stroke/transient ischemic attack (TIA)/peripheral thromboembolism and age 75 years. The 2012 ESC guidelines recommend use of the CHA2DS2-VASc score, with oral anticoagulation for all patients with a score > 0, except for female patients younger than 65 years with “lone AF” (despite their score of 1).3 The Canadian Cardiovascular Society (CCS), in its 2014 update, took a novel approach in an attempt to simplify and optimize AF anticoagulation guidance.4 The CCS Guidelines Committee recommended a 2-step method that it called the CCS Algorithm for oral anticoagulation in AF, as illustrated in Figure 1. Recognizing the prime role of age as an AF risk factor, the CCS recommended anticoagulating all patients aged 65 years. Then, patients younger than 65 years with additional major risk factors (stroke/TIA, hypertension, heart failure, or diabetes) are identified and recommended for anticoagulation. Finally, patients with vascular disease (coronary/aortic/peripheral) are given aspirin, based on the weakness of vascular disease only as a risk factor for AF-related
Received for publication November 24, 2014. Accepted November 24, 2014. Corresponding author: Dr Stanley Nattel, 5000 Belanger St E, Montreal, Quebec H1T 1C8, Canada. Tel.: þ1-514-376-3330; fax: þ1-514-376-1355. E-mail: [email protected] See page 2 for disclosure information.
stroke3 and the fact that these patients have a clear indication for aspirin therapy based on their vascular disease. In this issue of the Canadian Journal of Cardiology, Lip et al. present the results of an analysis of the CCS algorithm.5 With the use of data from the Danish nationwide cohort, they identified > 22,000 patients with a Congestive Heart Failure, Hypertension, Age, Diabetes, Stroke/Transient Ischemic Attack (CHADS2) score of 0. Among these, they considered the outcome of patients who would have been anticoagulated according to the CHA2DS2-VASc score, but not according to their determination using the CCS algorithm. Among these patients, the stroke risk was 4.32 per 100 patient-years, clearly representing a substantial risk. Thus, Lip et al. argue that the CCS algorithm is flawed and CHA2DS2-VASc should be used instead. Cairns et al. respond for the CCS AF Guidelines Committee in an editorial.6 They identified 3 sets of patient characteristics responsible for the high stroke risk in the analysis by Lip et al.5 These characteristics are: (1) systemic embolism (n ¼ 54 patients); (2) left ventricular dysfunction (n ¼ 695 patients); and (3) vascular disease (n ¼ 1149 patients). Cairns et al.6 argue that the vast majority (if not all) of the first 2 groups would be anticoagulated using proper application of the CCS algorithm. They contend that the CCS guidelines, although not explicitly stating as much, intend systemic embolism to be treated in the same way as stroke/TIA, as they have been by all AF anticoagulation guidance schemes since CHADS2. Similarly, they indicate that although “heart failure” is not explicitly defined in the CCS algorithm, severe left ventricular dysfunction is included in that category, just as in the ESC guidelines.3 Finally, with respect to the vascular disease category, Cairns et al.6 point out that the stroke risk of patients with vascular disease in the Danish cohort reported by Lip et al. in this issue of the Canadian Journal of Cardiology5 is > 3 times greater than reported from the same cohort in 2 previous publications, and that this discrepancy requires explanation before any implications for the CCS algorithm can be assessed. In summary, the article by Lip et al. provides important information needed to refine the formulation of the CCS algorithm.5 In particular, the CCS Guidelines Committee must publish a clarification about the signification in the CCS
http://dx.doi.org/10.1016/j.cjca.2014.11.022 0828-282X/Ó 2015 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.
2
Canadian Journal of Cardiology Volume 31 2015
There is an ancient saying stating that “Competition among scholars increases knowledge”. The dialogue in this issue of the Canadian Journal of Cardiology is a clear example of how careful analysis and debate can improve our understanding of important clinical issues and also the tools available to deal with them. Funding Sources Canadian Institutes of Health Research and Quebec Heart and Stroke Foundation. Disclosures The author has no conflicts of interest to disclose. References Figure 1. The Canadian Cardiovascular Society (CCS) algorithm for directing anticoagulation in atrial fibrillation (AF) patients. ASA, acetylsalicylic acid; CAD, coronary artery disease; CHADS2, Congestive Heart Failure, Hypertension, Age, Diabetes, Stroke/Transient Ischemic Attack; eGFR, estimated glomerular filtration rate; INR, international normalized ratio; NOAC, novel oral anticoagulant; NSAID, nonsteroidal anti-inflammatory drug; OAC, oral anticoagulation; TIA, transient ischemic attack. *The CCS suggests that a NOAC be used in preference to warfarin for non-valvular AF, yMight require lower dosing. Reproduced from Verma et al.4 with permission from Elsevier.
algorithm of systemic embolism (equivalent to stroke/TIA) and severe left ventricular dysfunction (included in the heart failure category). Furthermore, the article by Lip et al. highlights the apparently unresolved issue of the importance of vascular disease as a risk factor for AF-related stroke. If the stroke risk associated with vascular disease can vary as much as 3.5-fold, from a hazard ratio of 1.14 compared relative to no risk factor cited in the ESC guidelines3 to an approximately 5% annual risk in the article by Lip et al.,5 there clearly needs to be better definition of low- vs high-risk vascular disease categories.
1. Ahmad Y, Lip GY, Lane DA. Recent developments in understanding epidemiology and risk determinants of atrial fibrillation as a cause of stroke. Can J Cardiol 2013;29(7 suppl):S4-13. 2. Ha A, Healey JS. The evolving role of stroke prediction schemes for patients with atrial fibrillation. Can J Cardiol 2013;29:1173-80. 3. Camm AJ, Lip GY, De Caterina R, et al. 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillationedeveloped with the special contribution of the European Heart Rhythm Association. Europace 2012;14:1385-413. 4. Verma A, Cairns JA, Mitchell LB, et al. 2014 Focused update of the Canadian Cardiovascular Society guidelines for the management of atrial fibrillation. Can J Cardiol 2014;30:1114-30. 5. Lip YH, Nielsen PB, Skjoth F, Rasmussen LH, Larsen TB. Atrial fibrillation patients categorized as “not for anticoagulation” according to the 2014 Canadian Cardiovascular Society algorithm are not “low risk.” Can J Cardiol 2015;31:24-8. 6. Cairns JA, Healey J, Macle L, Mitchell B, Verma A. The new Canadian Cardiovascular Society algorithm for antithrombotic therapy of atrial fibrillation is appropriately based on current epidemiologic data. Can J Cardiol 2015;31:20-3.
Journal News and Commentary
Canadian Cardiovascular Society 2014 Algorithm for Anticoagulation Therapy in Atrial Fibrillation Debated Stanley Nattel, MD Departments of Medicine, Montreal Heart Institute and Universite de Montre al, Montreal, Quebec, Canada
Atrial fibrillation (AF) is a major risk factor for ischemic stroke.1 Although AF-related strokes can be prevented by oral anticoagulation, because of an increased bleeding risk anticoagulation therapy is reserved for patients with increased stroke risk. A variety of systems have been developed over the years to identify appropriate patients for therapy.2 Risk factors are used extensively to determine which AF patients stand to benefit from oral anticoagulation. The most widely used algorithm at present is the Congestive Heart Failure, Hypertension, Age (75 years), Diabetes, Stroke/Transient Ischemic Attack, Vascular Disease, Age (65-74 years), Sex (Female) (CHA2DS2-VASc) system, endorsed by the European Society of Cardiology (ESC) and other agencies, which attributes 1 point each for age 65, congestive heart failure (including left ventricular dysfunction), hypertension, diabetes, vascular disease (myocardial infarction, peripheral arterial disease, complex aortic plaque), and female sex, while 2 points each are attributed to previous stroke/transient ischemic attack (TIA)/peripheral thromboembolism and age 75 years. The 2012 ESC guidelines recommend use of the CHA2DS2-VASc score, with oral anticoagulation for all patients with a score > 0, except for female patients younger than 65 years with “lone AF” (despite their score of 1).3 The Canadian Cardiovascular Society (CCS), in its 2014 update, took a novel approach in an attempt to simplify and optimize AF anticoagulation guidance.4 The CCS Guidelines Committee recommended a 2-step method that it called the CCS Algorithm for oral anticoagulation in AF, as illustrated in Figure 1. Recognizing the prime role of age as an AF risk factor, the CCS recommended anticoagulating all patients aged 65 years. Then, patients younger than 65 years with additional major risk factors (stroke/TIA, hypertension, heart failure, or diabetes) are identified and recommended for anticoagulation. Finally, patients with vascular disease (coronary/aortic/peripheral) are given aspirin, based on the weakness of vascular disease only as a risk factor for AF-related
Received for publication November 24, 2014. Accepted November 24, 2014. Corresponding author: Dr Stanley Nattel, 5000 Belanger St E, Montreal, Quebec H1T 1C8, Canada. Tel.: þ1-514-376-3330; fax: þ1-514-376-1355. E-mail: [email protected] See page 2 for disclosure information.
stroke3 and the fact that these patients have a clear indication for aspirin therapy based on their vascular disease. In this issue of the Canadian Journal of Cardiology, Lip et al. present the results of an analysis of the CCS algorithm.5 With the use of data from the Danish nationwide cohort, they identified > 22,000 patients with a Congestive Heart Failure, Hypertension, Age, Diabetes, Stroke/Transient Ischemic Attack (CHADS2) score of 0. Among these, they considered the outcome of patients who would have been anticoagulated according to the CHA2DS2-VASc score, but not according to their determination using the CCS algorithm. Among these patients, the stroke risk was 4.32 per 100 patient-years, clearly representing a substantial risk. Thus, Lip et al. argue that the CCS algorithm is flawed and CHA2DS2-VASc should be used instead. Cairns et al. respond for the CCS AF Guidelines Committee in an editorial.6 They identified 3 sets of patient characteristics responsible for the high stroke risk in the analysis by Lip et al.5 These characteristics are: (1) systemic embolism (n ¼ 54 patients); (2) left ventricular dysfunction (n ¼ 695 patients); and (3) vascular disease (n ¼ 1149 patients). Cairns et al.6 argue that the vast majority (if not all) of the first 2 groups would be anticoagulated using proper application of the CCS algorithm. They contend that the CCS guidelines, although not explicitly stating as much, intend systemic embolism to be treated in the same way as stroke/TIA, as they have been by all AF anticoagulation guidance schemes since CHADS2. Similarly, they indicate that although “heart failure” is not explicitly defined in the CCS algorithm, severe left ventricular dysfunction is included in that category, just as in the ESC guidelines.3 Finally, with respect to the vascular disease category, Cairns et al.6 point out that the stroke risk of patients with vascular disease in the Danish cohort reported by Lip et al. in this issue of the Canadian Journal of Cardiology5 is > 3 times greater than reported from the same cohort in 2 previous publications, and that this discrepancy requires explanation before any implications for the CCS algorithm can be assessed. In summary, the article by Lip et al. provides important information needed to refine the formulation of the CCS algorithm.5 In particular, the CCS Guidelines Committee must publish a clarification about the signification in the CCS
http://dx.doi.org/10.1016/j.cjca.2014.11.022 0828-282X/Ó 2015 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.
2
Canadian Journal of Cardiology Volume 31 2015
There is an ancient saying stating that “Competition among scholars increases knowledge”. The dialogue in this issue of the Canadian Journal of Cardiology is a clear example of how careful analysis and debate can improve our understanding of important clinical issues and also the tools available to deal with them. Funding Sources Canadian Institutes of Health Research and Quebec Heart and Stroke Foundation. Disclosures The author has no conflicts of interest to disclose. References Figure 1. The Canadian Cardiovascular Society (CCS) algorithm for directing anticoagulation in atrial fibrillation (AF) patients. ASA, acetylsalicylic acid; CAD, coronary artery disease; CHADS2, Congestive Heart Failure, Hypertension, Age, Diabetes, Stroke/Transient Ischemic Attack; eGFR, estimated glomerular filtration rate; INR, international normalized ratio; NOAC, novel oral anticoagulant; NSAID, nonsteroidal anti-inflammatory drug; OAC, oral anticoagulation; TIA, transient ischemic attack. *The CCS suggests that a NOAC be used in preference to warfarin for non-valvular AF, yMight require lower dosing. Reproduced from Verma et al.4 with permission from Elsevier.
algorithm of systemic embolism (equivalent to stroke/TIA) and severe left ventricular dysfunction (included in the heart failure category). Furthermore, the article by Lip et al. highlights the apparently unresolved issue of the importance of vascular disease as a risk factor for AF-related stroke. If the stroke risk associated with vascular disease can vary as much as 3.5-fold, from a hazard ratio of 1.14 compared relative to no risk factor cited in the ESC guidelines3 to an approximately 5% annual risk in the article by Lip et al.,5 there clearly needs to be better definition of low- vs high-risk vascular disease categories.
1. Ahmad Y, Lip GY, Lane DA. Recent developments in understanding epidemiology and risk determinants of atrial fibrillation as a cause of stroke. Can J Cardiol 2013;29(7 suppl):S4-13. 2. Ha A, Healey JS. The evolving role of stroke prediction schemes for patients with atrial fibrillation. Can J Cardiol 2013;29:1173-80. 3. Camm AJ, Lip GY, De Caterina R, et al. 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillationedeveloped with the special contribution of the European Heart Rhythm Association. Europace 2012;14:1385-413. 4. Verma A, Cairns JA, Mitchell LB, et al. 2014 Focused update of the Canadian Cardiovascular Society guidelines for the management of atrial fibrillation. Can J Cardiol 2014;30:1114-30. 5. Lip YH, Nielsen PB, Skjoth F, Rasmussen LH, Larsen TB. Atrial fibrillation patients categorized as “not for anticoagulation” according to the 2014 Canadian Cardiovascular Society algorithm are not “low risk.” Can J Cardiol 2015;31:24-8. 6. Cairns JA, Healey J, Macle L, Mitchell B, Verma A. The new Canadian Cardiovascular Society algorithm for antithrombotic therapy of atrial fibrillation is appropriately based on current epidemiologic data. Can J Cardiol 2015;31:20-3.