Strokes (brain attacks), although not true heart disorders, are caused by blockage or reduced blood flow to the brain. While some strokes occur when a blood vessel bursts, most happen due to clogged or blocked vessels to the brain, in the same way clogged vessels in the heart can cause a heart attack. Abnormal heart rhythms such as atrial fibrillation and atrial flutter can lead to the formation of blood clots in the heart. Such blood clots can break off and travel to the brain, block a vessel and cause a stroke. All strokes pose serious health threats.