Society guidelineCanadian Cardiovascular Society Atrial Fibrillation Guidelines 2010: Prevention of Stroke and Systemic Thromboembolism in Atrial Fibrillation and Flutter
Section snippets
Risk factors and risk estimation schemes
In the 5 landmark randomized clinical trials of oral anticoagulants (OACs) among patients with nonvalvular atrial fibrillation (AF),1, 2, 3, 4, 5, 6 most of whom had no previous stroke or TIA, control subjects had a mean 4.5% annual incidence of stroke (range, 3%-7%), over half of which resulted in death or permanent disability.7 The mean annual incidence of the composite of stroke or other systemic emboli was 5% (range, 3%-7.4%). These subjects had no contraindications to warfarin and no
Oral vitamin K antagonists and antiplatelet agents
An overview7 of the initial 5 randomized trials of oral vitamin K antagonists compared with no treatment found the incidence of ischemic stroke was reduced from 4.5% per year to 1.4% per year (relative risk reduction [RRR] 68%; 95% CI, 50%-79%; P < .001). The rate of major hemorrhage with vitamin K antagonists was 1.3% per year vs 1% per year in controls. The most recent meta-analysis of such trials26 included 1 additional trial (of secondary prevention of stroke) and calculated an RRR of 64%
Risk of Hemorrhage
The efficacy of any antithrombotic therapy for the prevention of ischemic stroke must be balanced against the risk of major hemorrhage, particularly cerebral hemorrhage, which is often fatal. In each of the initial randomized trials of antithrombotic therapies, the principal outcome was the composite of ischemic stroke or systemic embolus. Although hemorrhage and the subsets of intracranial and intracerebral hemorrhage were generally reported, the net benefit for major clinical outcomes was not
Elderly patients
Advanced age (>75 years) has been consistently noted as a risk factor for both ischemic stroke and major hemorrhage, particularly intracranial. Hylek et al53 reported a series of 472 patients aged ≥65 years (153 patients aged ≥80 years), with electrocardiogram-verified AF, newly started on warfarin at the study institution, and managed by the on-site anticoagulation clinic. Anticoagulation control was very good, with 56% of person-time within the INR range of 2.0 to 3.0, 29% below 2.0, 11%
Coronary Artery Disease
The clinician managing a patient with AF must often deal with concomitant coronary artery disease in the settings of primary prevention, stable coronary artery disease, an acute coronary syndrome (ACS), or percutaneous coronary intervention (PCI). There is good evidence for the use of aspirin for primary prevention,74, 75 for aspirin or clopidogrel for stable coronary artery disease,76 for aspirin supplemented by clopidogrel for up to 1 year following an ACS (with or without PCI77, 78, 79, 80,
Invasive Procedures
When a patient receiving an OAC or antiplatelet agent is to undergo a surgical or diagnostic procedure that has a risk of major bleeding, the risk of a thromboembolic event occurring while the antithrombotic agent is reduced or stopped must be weighed against the goal of a reduced risk of major bleeding.94, 95 We suggest that such patients be stratified as to their risk of stroke, which can range from <1% to >20% per year. If there is a very low to moderate risk of stroke (CHADS2 ≤ 2), the
Stroke Management in Patients With AF
Among AF patients experiencing a stroke, the high rate of recurrence suggested that there was some urgency in initiating anticoagulation after the occurrence of embolic stroke. The International Stroke Trial Collaborative Group randomized 18,451 patients with ischemic stroke within 24 hours of onset to subcutaneous unfractionated heparin (5000 IU twice a day or 12,500 IU twice a day), aspirin 300 mg per day, both, or neither and maintained for 14 days or until prior hospital discharge.24 CT
Hemorrhage on OAC Therapy
The major determinants of OAC-induced bleeding are the INR, patient characteristics, and the concomitant use of drugs that interfere with hemostasis. The acute management of hemorrhage in a patient receiving OAC requires a graded response according to published guidelines,103 beginning with the immediate measurement of the INR, stopping the OAC, and assessment of the severity of hemorrhage. If there is major bleeding, vitamin K may be given intravenously, and if the bleeding is life
Pharmacogenomics
Eventually, pharmacogenomic algorithms may allow more rapid and safe determinations of initial warfarin dosage, particularly among patients whose warfarin requirements are particularly low or high.104 For the present, routine genetic testing is not advised in the management of therapy with a vitamin K antagonist.
Rhythm control and stroke risk
An overview105 of the 5 trials that compared the strategies of rhythm vs rate control in AF found a mortality of 13.0% with rate control vs 14.6% with rhythm control (odds ratio 0.87, P = .09). The rates of ischemic stroke and major hemorrhage were similar. The AFFIRM trial58 is by far the largest, mandated anticoagulation (INR 2.0-3.0) in the rate-control group (85% maintained warfarin) and strongly encouraged in the rhythm-control group, while allowing cessation at the physician's discretion
Acknowledgements
The authors are grateful to Grant Stotts, MD, FRCPC, for advice and liaison with the Canadian Stroke Network and to Marie-Josee Martin and Jody McCombe for final transcription of the manuscript. Administrative and technical support was provided by the Canadian Cardiovascular Society.
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2020, Canadian Journal of CardiologyCitation Excerpt :Although this risk is comparable with that of planned cardioversion in patients with AF of > 48 hours who receive OAC, these reports were limited by selection bias; describing low-risk patients who presented in a stable state early in the 48-hour window, with a significant proportion receiving OAC.339 Moreover, despite the significant selection bias the rate of stroke/systemic embolism substantially exceeded the established threshold for OAC initiation (1.5% per year or 0.12% per 30 days).351 More recent data specifically focused on patients who underwent cardioversion for AF of < 48 hours in the absence of OAC provide a more disquieting viewpoint.352-359
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The disclosure information of the authors and reviewers is available from the CCS on the following Web sites: www.ccs.ca and www.ccsguidelineprograms.ca.
This statement was developed following a thorough consideration of medical literature and the best available evidence and clinical experience. It represents the consensus of a Canadian panel comprised of multidisciplinary experts on this topic with a mandate to formulate disease-specific recommendations. These recommendations are aimed to provide a reasonable and practical approach to care for specialists and allied health professionals obliged with the duty of bestowing optimal care to patients and families, and can be subject to change as scientific knowledge and technology advance and as practice patterns evolve. The statement is not intended to be a substitute for physicians using their individual judgment in managing clinical care in consultation with the patient, with appropriate regard to all the individual circumstances of the patient, diagnostic and treatment options available and available resources. Adherence to these recommendations will not necessarily produce successful outcomes in every case.
- e
For a complete listing of committee members, see Gillis AM, Skanes AC. Canadian Cardiovascular Society Atrial Fibrillation Guidelines 2010: Implementing GRADE and Achieving Consensus. Can J Cardiol 2011;27:27-30.