429fa52b_ke_Campaign___strokechallenges__What_you_can_do
[Risk factor] Atrial fibrillation (AF) AF affects fewer than one percent of people under age 60, but is more prevalent in older people. It is responsible for one in four strokes after age 80, and is associated with high mortality and disability. [Why it affects stroke risk] AF refers to irregular contraction of the atrium - the chamber where blood enters the heart. aF can lead to blood stagnation and increased clotting. [What you can do] 
Warfarin, a blood-thinning medication, can reduce the risk of stroke in people with aF. People under age 60 with aF and no other stroke risk factors may benefit from aspirin. Importantly, pacemakers have no effect on the risk of stroke associated with AF.
NINDS Know Stroke Campaign - strokechallenges
What you can do