Age Threshold for Ischemic Stroke Risk in Atrial Fibrillation

Area of Science:

• Cardiology
• Neurology
• Public Health

Background:

• Older age is a significant risk factor for stroke in atrial fibrillation (AF).
• Current age thresholds in stroke risk scores like CHA₂DS₂-VASc may not be universally applicable across different ethnicities.
• Investigating specific age thresholds for Asian populations is crucial for accurate stroke risk assessment.

Purpose of the Study:

• To determine the appropriate age threshold for ischemic stroke risk in Asian patients with atrial fibrillation.
• To evaluate the impact of age as a risk factor independent of other CHA₂DS₂-VASc criteria in this population.

Main Methods:

• Analysis of a large cohort (426,650 patients) of oral anticoagulant-naive nonvalvular AF patients from South Korea (2005-2015).
• Inclusion of patients with low to intermediate CHA₂DS₂-VASc scores (males 0-2, females 1-3) excluding gender-related points.
• Assessment of ischemic stroke risk stratified by age groups within the AF patient cohort.

Main Results:

• Patients aged 65-74 years with no other risk factors had a significantly higher stroke risk (4.76/100PY) compared to those with one non-age risk factor (1.87/100PY).
• Individuals aged 55-59 years with no risk factors exhibited a stroke risk (1.94/100PY) similar to patients with one risk score (2.06/100PY).
• Patients aged 65-69 years with no additional risk factors showed a similar stroke risk (4.08/100PY) to those with two non-gender risk scores (4.42/100PY).

Conclusions:

• Age is a critical predictor of ischemic stroke in atrial fibrillation patients, especially those at low-to-intermediate risk.
• The findings suggest that the current age threshold of ≥65 years in the CHA₂DS₂-VASc score may be too high for Asian AF patients.
• Lowering the age threshold to ≥55 years could provide a more accurate stroke risk assessment for Asian individuals with AF.