The new Canadian Cardiovascular Society Atrial Fibrillation (AF) Guidelines strongly recommend that all patients with AF be stratified using a predictive index for stroke (e.g., CHADS2) and risk of bleeding (e.g., HAS-BLED), and that most patients with AF should receive antithrombotic therapy.
As part of the national Facilitating REview and EDucation to OptiMize stroke prevention in Atrial Fibrillation (FREEDOM AF) knowledge translation program, data was collected on 4280 patients (≥18 years without a significant heart valve disorder) from 438 general practitioners undertaking an ethics-approved chart audit describing characteristics, AF and medical history, antithrombotic treatment, and estimated risk (Feb-Apr 2011).
The median age (25th
percentiles) was 77 years (69, 83; 58% ≥75 yrs); 42% were female. AF duration was 5 (3, 10) yrs, with 30% paroxysmal, 24% persistent, and 42% permanent/accepted; 69% were in AF at the most recent visit. Prior history included: stroke (11%), transient ischemic attack (13%), systemic embolism (2%), hypertension (75%), heart failure (20%), and diabetes (27%). Agreement between physician-estimated stroke and bleeding risks (using a formal risk assessment tool in 51% and 26%, respectively), and CHADS 2
(stroke) and HAS-BLED (bleeding) risk score estimates are seen in the Figure
. Antithrombotic therapy included: warfarin (82% current/5% past), ASA (23%), clopidogrel (3%), and dabigatran (<0.5%). Reported contraindications to oral anticoagulant therapy included: high risk for/prior bleeding/ICH (7%), frequent falls/frailty (5%), unable to adhere/monitor warfarin (4%), need for dual antiplatelet therapy (3%), comorbid illness (3%), and patient refusal (2%). Among 3510 (82%) patients currently on warfarin, the estimated time in the therapeutic range (using Rosendaal et al method) was: 53% (INR 2-3), 26% (<2), and 19% (>3).
We describe a large, real-world elderly Canadian AF population at important risk for stroke. Physicians were unable to give an estimate of stroke and bleeding risk in 15% and 25% of their AF patients, respectively; when such estimates were provided, they were based on a predictive stroke and bleeding risk index in only 50% and 25% of patients, respectively. Furthermore, there is apparent underestimation of especially stroke but also bleeding risk in a substantial number of patients. Despite the relatively high use of antithrombotic therapy, the estimated day-to-day anticoagulation INR target was achieved in only half of current warfarin-treated patients. These findings suggest an opportunity to enhance knowledge translation to primary care physicians; this will be undertaken in the prospective registry phase of the FREEDOM AF program.
© 2011 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.