Residual Stroke Risk Among Patients With Atrial Fibrillation Prescribed Oral Anticoagulants: A Patient-Level...

Area of Science:

• Cardiology
• Neurology
• Pharmacology

Background:

• Atrial fibrillation (AF) patients on oral anticoagulation have residual risk for ischemic stroke and systemic embolism (SE).
• Identifying high-risk individuals is crucial for optimizing stroke prevention strategies.

Purpose of the Study:

• To analyze residual stroke/SE risk in AF patients treated with oral anticoagulation.
• To stratify risk based on CHA₂DS₂-VASc score, AF type, and prior stroke history.

Main Methods:

• Pooled individual patient data from 5 landmark AF oral anticoagulation trials (COMBINE AF).
• Calculated stroke/SE rates across CHA₂DS₂-VASc score strata, AF types (paroxysmal vs. nonparoxysmal), and stroke history.
• Included 71,794 AF patients randomized to direct oral anticoagulants or vitamin K antagonists.

Main Results:

• Overall stroke/SE rate was 1.33%/year; higher in nonparoxysmal AF (1.38%/year) than paroxysmal AF (1.15%/year).
• Stroke/SE risk increased with CHA₂DS₂-VASc score, reaching 1.67%/year for scores ≥4.
• Patients with nonparoxysmal AF and CHA₂DS₂-VASc ≥4 had a 1.75%/year risk; those with prior stroke had a 2.51%/year risk.

Conclusions:

• AF type, CHA₂DS₂-VASc score, and stroke history identify patients with significant residual stroke/SE risk (1.5%-2.5%/year) despite oral anticoagulation.
• Further evaluation of additional stroke/SE prevention strategies for these high-risk patients is warranted.