From the Guidelines
Anticoagulation in atrial fibrillation (AFib) should be initiated based on the patient's stroke risk, primarily assessed using the CHA₂DS₂-VASc score, with a score of 2 or more indicating elevated thromboembolic risk for men and a score of 1 being considered for anticoagulation decisions 1. The decision to start anticoagulation in AFib is guided by the patient's stroke risk, with the CHA₂DS₂-VASc score being the primary assessment tool.
- A CHA₂DS₂-VASc score of 2 or more is recommended as an indicator of elevated thromboembolic risk for decisions on initiating oral anticoagulation in men 1.
- A CHA₂DS₂-VASc score of 1 should be considered an indicator of elevated thromboembolic risk for decisions on initiating oral anticoagulation 1. Key considerations for initiating anticoagulation include:
- Oral anticoagulation is recommended in patients with clinical AFib at elevated thromboembolic risk to prevent ischemic stroke and thromboembolism 1.
- Direct oral anticoagulant therapy may be considered in patients with asymptomatic device-detected subclinical AFib and elevated thromboembolic risk, excluding patients at high risk of bleeding 1. The most recent guidelines from 2024 emphasize the importance of individualized reassessment of thromboembolic risk at periodic intervals in patients with AFib to ensure anticoagulation is started in appropriate patients 1. Oral anticoagulation is recommended in all patients with AFib and hypertrophic cardiomyopathy or cardiac amyloidosis, regardless of CHA₂DS₂-VASc score, to prevent ischemic stroke and thromboembolism 1.
From the FDA Drug Label
Oral anticoagulation therapy with warfarin is recommended in patients with persistent or paroxysmal AF (PAF) (intermittent AF) at high risk of stroke (i.e., having any of the following features: prior ischemic stroke, transient ischemic attack, or systemic embolism, age >75 years, moderately or severely impaired left ventricular systolic function and/or congestive heart failure, history of hypertension, or diabetes mellitus)
The criteria for starting anticoagulation in atrial fibrillation (AFib) include:
- Prior ischemic stroke, transient ischemic attack, or systemic embolism
- Age >75 years
- Moderately or severely impaired left ventricular systolic function and/or congestive heart failure
- History of hypertension
- Diabetes mellitus Patients with these features are considered at high risk of stroke and should be started on anticoagulation therapy, such as warfarin 2.
For patients with AF and mitral stenosis, anticoagulation with oral warfarin is recommended 2. For patients with AF and prosthetic heart valves, anticoagulation with oral warfarin should be used; the target INR may be increased and aspirin added depending on valve type and position, and on patient factors 2.
In the ROCKET AF study, patients with nonvalvular atrial fibrillation (AF) had to have one or more of the following additional risk factors for stroke: a prior stroke (ischemic or unknown type), transient ischemic attack (TIA) or non-CNS systemic embolism, or 2 or more of the following risk factors: age ≥75 years, hypertension, heart failure or left ventricular ejection fraction ≤35%, or diabetes mellitus 3.
From the Research
Criteria for Starting Anticoagulation in Atrial Fibrillation
The decision to start anticoagulation in patients with atrial fibrillation (AF) is guided by the risk of thromboembolic events, which can be assessed using the CHA₂DS₂-VASc score. This score takes into account several factors, including:
- Congestive heart failure
- Hypertension
- Age ≥ 75 years (doubled)
- Diabetes
- Stroke or transient ischemic attack (doubled)
- Vascular disease
- Age 65-74 years
- Sex (female)
CHA₂DS₂-VASc Score and Anticoagulation
Studies have shown that the CHA₂DS₂-VASc score is a useful tool in predicting the risk of stroke and systemic embolization in patients with AF 4, 5, 6, 7. A score of 2 or higher indicates a high risk of thromboembolic events and suggests the need for anticoagulation. However, the decision to anticoagulate patients with a score of 1 is less clear-cut.
Patients with a CHA₂DS₂-VASc Score of 1
Research suggests that patients with a CHA₂DS₂-VASc score of 1 may still be at risk of thromboembolic events, particularly if they have certain risk factors such as age 65-74 years or vascular disease 8. However, the risk may vary depending on the specific risk factor present.
Key Findings
- The CHA₂DS₂-VASc score is a useful tool in predicting the risk of stroke and systemic embolization in patients with AF 4, 5, 6, 7.
- A score of 2 or higher indicates a high risk of thromboembolic events and suggests the need for anticoagulation.
- Patients with a score of 1 may still be at risk of thromboembolic events, particularly if they have certain risk factors such as age 65-74 years or vascular disease 8.
- The decision to anticoagulate patients with a score of 1 should be made on an individual basis, taking into account the patient's specific risk factors and medical history.
Risk Factors and Anticoagulation
The following risk factors may influence the decision to start anticoagulation in patients with AF:
- Age ≥ 75 years
- History of stroke or transient ischemic attack
- Vascular disease
- Congestive heart failure
- Hypertension
- Diabetes
- Female sex
It is essential to consider these risk factors when deciding whether to start anticoagulation in patients with AF, as they can significantly impact the risk of thromboembolic events 4, 5, 6, 7, 8.