In a patient with atrial fibrillation (AF) and an annual stroke risk of ≥ 1% but < 2%, what additional characteristic should be considered during shared decision-making that may increase the patient's risk of thromboembolism?

Left Ventricular Ejection Fraction as a Risk Factor for Thromboembolism in Atrial Fibrillation

According to the 2023 Atrial Fibrillation guidelines, left ventricular ejection fraction (LVEF) should be considered during shared decision making for patients with atrial fibrillation who have an annual stroke risk ≥1% but <2%, as reduced LVEF increases the risk of thromboembolism.

Understanding Risk Factors in Atrial Fibrillation

The 2023 ACC/AHA/ACCP/HRS guidelines for atrial fibrillation management emphasize the importance of considering additional risk factors beyond the traditional CHA₂DS₂-VASc score when making anticoagulation decisions, particularly for patients in the intermediate risk category (annual stroke risk ≥1% but <2%).

Key Risk Factors to Consider:

1. Left Ventricular Ejection Fraction (LVEF):

   • Reduced LVEF is a significant risk factor for thromboembolism that may not be fully captured in the CHA₂DS₂-VASc score
   • The European Society of Cardiology Working Group on Cardiovascular Pharmacotherapy specifically identifies impaired left ventricular systolic function as an independent predictor of stroke 1

2. Other Risk Modifiers:

   • Type of AF (paroxysmal vs. persistent) is less important than previously thought
   • AF symptoms are poor indicators of thromboembolic risk 1
   • Biomarkers (such as cardiac troponin) may help refine risk assessment 1

Why LVEF Matters in Thromboembolism Risk

LVEF is particularly important because:

• It represents a direct measure of cardiac function that affects blood flow dynamics
• Reduced LVEF promotes blood stasis in the left atrium and left atrial appendage
• It may indicate underlying structural heart disease that increases stroke risk
• The 2001 ACC/AHA/ESC guidelines specifically identified abnormal LV systolic function as an independent predictor of stroke 1

Clinical Decision-Making Algorithm

For patients with AF and annual stroke risk ≥1% but <2%:

1. Assess baseline CHA₂DS₂-VASc score

2. Evaluate LVEF:

   • If LVEF is reduced (<40%), consider this a significant additional risk factor
   • If LVEF is moderately reduced (40-50%), consider this a moderate additional risk factor
   • If LVEF is preserved (>50%), look for other risk modifiers

3. Consider other risk modifiers:

   • Biomarkers (troponin, NT-proBNP)
   • Left atrial size and function
   • Presence of silent cerebral infarcts

4. Make anticoagulation decision:

   • With reduced LVEF and annual stroke risk ≥1%, anticoagulation is generally recommended
   • With preserved LVEF, decision can be more individualized based on other factors and patient preferences

Common Pitfalls to Avoid

• Don't focus solely on AF pattern: The type of AF (paroxysmal vs. persistent) should not be the primary factor in anticoagulation decisions 1
• Don't rely on symptoms: AF-related symptoms are poor indicators of stroke risk 1
• Don't ignore LVEF: Even if not explicitly included in CHA₂DS₂-VASc, reduced LVEF is an important independent risk factor
• Don't underestimate shared decision-making: Patient preferences and values should be incorporated into the final decision, especially in intermediate risk cases

By considering LVEF during shared decision-making for patients with atrial fibrillation who have an annual stroke risk ≥1% but <2%, clinicians can make more informed decisions about anticoagulation therapy, potentially reducing the risk of thromboembolic events and improving patient outcomes.