How should we treat patients with atrial fibrillation and a CHADS2score of 1?

Abstract

Warfarin is more effective than aspirin at preventing stroke in atrial fibrillation (AF), but is associated with hemorrhagic events. In patients with a CHADS 2 score of 1, the present guidelines for the management of AF indicate that the choice between oral anticoagulation and aspirin is discretionary, depending on each patient and on the bleeding risk. In post-hoc ana lysis and observational data, oral anticoagulation seemed to be associated with a decreased risk of events in such patients, whereas no such result seems apparent for patients receiving only an antiplatelet agent. We think that such patients should thus be treated with oral anticoagulant whenever possible, unless there is a high risk of a hemorrhagic event. Randomized trials have demonstrated that, compared with a placebo, adjusted-dose warfarin reduces the incidence of stroke by approximately 60% in patients with AF. By contrast, antiplatelet agents have only demonstrated a reduction of approximately 20% in the incidence of stroke. [1]. Oral anticoagulation with vitamin K antagonists (VKAs) is better at reducing the risk of stroke but is associated with the incidence of serious bleeding [2]. The CHADS 2 score has been used to identify AF patients at low risk of stroke (less than 1–2% per year), for whom the risks and inconvenience of VKAs outweigh their potential benefits [3]. The CHADS 2 score is calculated as one point each for a history of heart failure, a history of hypertension, age over 75 years, diabetes and two points for a prior stroke [3]. It does not apply to patients with a valvular prosthesis or a mitral stenosis for whom an oral anticoagulant is recom mended, regardless of the risk-stratification score. In patients with an intermediate risk of stroke, that is, a CHADS 2 score of 1 (2–4% annual rate of stroke), available evidence from clinical trials is inconclusive, and the present American Heart Association (AHA)/American College of Cardiology (ACC)/European Society of Cardiology (ESC) guidelines for the management of AF still indicate that the choice between VKAs and aspirin in these patients is discretionary, depending on each patient and especially on the bleeding risk [4]. This uncertainty in treatment guidance [4,5] leads to significant differences in the prescription of anticoagulation and antiplatelet therapy among these patients from case-to-case, and is finally subject to physician discretion and patient preference [6–8].