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[Antithrombotic therapy of atrial fibrillation]
Insights
Atrial fibrillation significantly increases stroke risk. Oral anticoagulation with vitamin K antagonists (INR 2-3) effectively reduces ischemic stroke and all-cause mortality in high-risk patients.
Area of Science:
- Cardiology
- Neurology
- Pharmacology
Background:
- Atrial fibrillation (AF) is a major risk factor for cerebrovascular accident (stroke), increasing incidence fivefold compared to the general population.
- Age is the primary risk factor for stroke in AF patients, but hypertension, prior stroke, heart failure, and diabetes also identify high-risk individuals.
Purpose of the Study:
- To evaluate the efficacy and safety of oral anticoagulation and aspirin for primary stroke prevention in non-valvular atrial fibrillation (NVAF).
Main Methods:
- Analysis of combined results from six large-scale randomized controlled multicenter trials involving over 2,800 patients with NVAF.
- Comparison of vitamin K antagonist therapy (INR 2-3) versus placebo or control.
- Evaluation of aspirin therapy as an alternative or adjunct treatment.
Main Results:
- Vitamin K antagonist therapy significantly reduced ischemic stroke risk by 64% (p < 0.001) and all-cause mortality by 28% (p = 0.038).
- Aspirin therapy showed a trend towards reducing ischemic stroke risk by 22% (p = 0.053).
- A slight, non-significant increase in cerebral hemorrhage risk was observed with vitamin K antagonists (+2.7%).
Conclusions:
- Oral anticoagulation with vitamin K antagonists is highly effective for stroke prevention in NVAF patients with identified risk factors.
- Aspirin may be considered for younger patients (<75 years) without additional risk factors.
- The role of combined aspirin-oral anticoagulant therapy requires further investigation.
Abstract:
In comparison with the incidence of cerebrovascular accident in the general population, atrial fibrillation increases the risk by a factor of five. Although age is without doubt the main risk factor for cerebrovascular accidents in patients with permanent of paroxysmal non-valvular atrial fibrillation, other independent risk factors have been identified: a previous history of hypertension, cerebrovascular accident, heart failure or diabetes. These factors enable identification of a population at risk in which oral anticoagulation may be recommended with an excellent efficacy/risk ratio. Six large scale randomised controlled multicenter trials of primary prevention have been published with a total of over 2,800 patients with non-valvular atrial fibrillation. The combined results of these trials show that treatment with vitamin K antagonist (INR 2-3) leads to a significant reduction in the risk of an ischaemic cerebrovascular accident of 64% (95% CI [51-74]; p < 0.001) and in the risk of death from all causes of 28% (95% CI [12-47]; p = 0.038) with a slight increase in the risk of cerebral haemorrhage (+ 2.7% NS). Although the benefits of aspirin therapy are not as impressive (reduction of the risk of an ischaemic cerebrovascular accident of 22%; 95% CI [0-39]; p = 0.053), this alternative may be proposed in patients under 75 years of age without the previously mentioned risk factors. The value of combined aspirin-oral anticoagulant therapy, especially in high risk patients, has not yet been established and is under evaluation.