What is the effect of atrial fibrillation?

Heart rate / stroke: Two issues with afib. The first is stroke. Afib is a risk for stroke, and thus all patients with afib need some sort of blood thinner. Whether that is an Aspirin or full anticoagulants such as Coumadin (warfarin) depends on your risks and your doctor will let you know that. The second is heart rate. If the afib is too fast or too slow, the rate will need to be treated also.

Irregular heartbeat: A fib causes the upper chambers to beat very fast, so that they quiver instead of beating in a coordinated fashion. This can result in blood pooling in the upper chambers, increasing the risk of clot formation which can cause stroke. A fib results in an irregular, sometimes fast pulse rate, which can cause symptoms, such as palpitations, shortness of breath, fatigue, dizziness, and chest pain.