Thromboprophylaxis In Atrial Fibrillation Research Articles

Anticoagulation as thromboprophylaxis for atrial fibrillation: implications in the ‘real world’ and the need for risk stratification

Anticoagulation as thromboprophylaxis for atrial fibrillation: implications in the ‘real world’ and the need for risk stratification

Risk factors for stroke and thromboprophylaxis in atrial fibrillation: what happens in daily clinical practice? The GEFAUR-1 study.

We determine the risk for stroke of patients with atrial fibrillation in the emergency department (ED) and analyze the use of stroke prophylaxis in this setting. This was a cross-sectional study carried out in 12 EDs. Clinical variables, risk factors for stroke, the prophylaxis prescribed, and the reasons for not initiating anticoagulation were collected. Risk factors and indications for therapy were evaluated according to the American College of Chest Physicians' 1998 recommendations. Of 1,178 patients included, 69% were not taking anticoagulants. Of the latter, 89% patients had indications for anticoagulation (age >75 years 59%, hypertension 56%, cardiac disorders 29%, heart failure 22%, diabetes 22%, previous embolism 14%), and 63% of the patients had 2 or more risk factors. Anticoagulation was prescribed in the ED to 27% of patients (67% with warfarin, 33% low-weight heparin plus warfarin), antiplatelets to 20% of patients, and no thromboprophylaxis to 53% of these eligible patients. Anticoagulants were prescribed in only 9% of patients with risk factors and current prophylaxis with antiplatelet agents. The main reasons for not prescribing anticoagulation in the presence of risk factors were advanced age (11%), contraindication for anticoagulation (27%), or because it was not considered to be indicated by the physicians (23%). Most patients seen in the ED with atrial fibrillation are at high risk of stroke. Despite this risk, anticoagulation is underused in this setting, mainly because of the influence of advanced age on medical decisions and the reluctance to change current antiplatelet therapy.

Risk factors for stroke and thromboprophylaxis in atrial fibrillation: what happens in daily clinical practice? The GEFAUR-1 study

Study objectivesWe determine the risk for stroke of patients with atrial fibrillation in the emergency department (ED) and analyze the use of stroke prophylaxis in this setting. MethodsThis was a cross-sectional study carried out in 12 EDs. Clinical variables, risk factors for stroke, the prophylaxis prescribed, and the reasons for not initiating anticoagulation were collected. Risk factors and indications for therapy were evaluated according to the American College of Chest Physicians' 1998 recommendations. ResultsOf 1,178 patients included, 69% were not taking anticoagulants. Of the latter, 89% patients had indications for anticoagulation (age >75 years 59%, hypertension 56%, cardiac disorders 29%, heart failure 22%, diabetes 22%, previous embolism 14%), and 63% of the patients had 2 or more risk factors. Anticoagulation was prescribed in the ED to 27% of patients (67% with warfarin, 33% low-weight heparin plus warfarin), antiplatelets to 20% of patients, and no thromboprophylaxis to 53% of these eligible patients. Anticoagulants were prescribed in only 9% of patients with risk factors and current prophylaxis with antiplatelet agents. The main reasons for not prescribing anticoagulation in the presence of risk factors were advanced age (11%), contraindication for anticoagulation (27%), or because it was not considered to be indicated by the physicians (23%). ConclusionMost patients seen in the ED with atrial fibrillation are at high risk of stroke. Despite this risk, anticoagulation is underused in this setting, mainly because of the influence of advanced age on medical decisions and the reluctance to change current antiplatelet therapy.

1855 Risk factors for stroke and thromboprophylaxis in atrial fibrillation. What happens in daily clinical practice? (The GEFAUR-1 study)

1855 Risk factors for stroke and thromboprophylaxis in atrial fibrillation. What happens in daily clinical practice? (The GEFAUR-1 study)

A prospective randomized trial of aspirin-clopidogrel combination therapy and dose-adjusted warfarin on indices of thrombogenesis and platelet activation in atrial fibrillation

ObjectivesThis study was designed to investigate whether or not combination aspirin-clopidogrel therapy would reduce markers of thrombogenesis and platelet activation in atrial fibrillation (AF), in a manner similar to warfarin. BackgroundDose-adjusted warfarin is beneficial as thromboprophylaxis in AF, but potentially serious side effects and regular monitoring leave room for alternative therapies. MethodsWe randomized 70 patients with nonvalvular AF who were not on any antithrombotic therapy to either dose-adjusted warfarin (international normalized ratio 2 to 3) (Group I) or combination therapy with aspirin 75 mg and clopidogrel 75 mg (Group II). Plasma indices of thrombogenesis (fibrin D-dimer, prothrombin fragment 1+2) and platelet activation (beta-thromboglobulin [TG] and soluble P-selectin) were quantified, along with platelet aggregation responses to standard agonists, at baseline (pretreatment) and at six weeks posttreatment. ResultsPretreatment levels of fibrin D-dimer (p = 0.001), beta-TG (p = 0.01) and soluble P-selectin (p = 0.03) were raised in patients with AF, whereas plasma prothrombin fragment 1+2 levels and platelet aggregation were not significantly different compared with controls. Dose-adjusted warfarin reduced plasma levels of fibrin D-dimer, prothrombin fragment 1+2 and beta-thromboglobulin levels at six weeks (all p < 0.001), enhanced plasma levels of soluble P-selectin (p < 0.001) and had no significant effect on platelet aggregation. Aspirin-clopidogrel combination therapy made no difference to the plasma markers of thrombogenesis or platelet activation (all p = NS), but the platelet aggregation responses to adenosine diphosphate (p < 0.001) and epinephrine (p = 0.02) were decreased. ConclusionsAspirin-clopidogrel combination therapy failed to reduce plasma indices of thrombogenesis and platelet activation in AF, although some aspects of ex vivo platelet aggregation were altered. Anticoagulation with warfarin may be superior to combination aspirin-clopidogrel therapy as thromboprophylaxis in AF.

ATRIAL FIBRILLATION, THROMBOEMBOLISM AND ANTITHROMBOTIC THERAPY

SUMMARYAtrial fibrillation is the commonest sustained disorder of cardiac rhythm and is associated with increased risk of stroke and thromboembolic events. Warfarin (dose‐adjusted to a target INR of 2.0‐3.0) has been well established to reduce this risk of stroke by 68% (95% CI 50‐79%), while aspirin provides a risk reduction of 21% (95% CI 0‐38%). Nevertheless, warfarin confers a risk of bleeding and the inconvenience of regular monitoring checks, while aspirin seems effective only for certain low‐risk subgroups. Thus there have been strenuous efforts to improve thromboprophylaxis in atrial fibrillation, by using low‐intensity anticoagulation regimens, combination antiplatelet therapy and refinement of risk stratification strategies. Attempts at using a low‐intensity, fixed‐dose warfarin regimen have, however, been disappointing. For now, a strategy of risk stratification should be adopted to identify highest risk patients with atrial fibrillation who would benefit from anticoagulation.

Warfarin and aspirin as thromboprophylaxis in atrial fibrillation

1. Anticoagulant therapy with warfarin is now established as effective thromboprophylaxis against stroke in atrial fibrillation, in high-risk persons. Aspirin is indicated in moderate-risk persons or if warfarin is contraindicated. 2. Risk stratification is suggested, using clinical factors supplemented by echocardiography, to aid choice of prophylaxis. 3. Further studies are required to establish how best to identify undiagnosed patients who have atrial fibrillation; to develop new therapeutic strategies; and to refine risk stratification to define which patients with atrial fibrillation are at the highest risk of stroke.