Atrial FibrillationAtrial Fibrillation is when the heart fails to beat in a systematic rhythm, resulting in a quivering of the heart muscle. This disturbs the normal rhythm of the heart and can become dangerous when blood can pool in portions of the heart and blood clots are likely to form. These clots can cause strokes. The most common causes of atrial fibrillation can be heart attack, high blood pressure and coronary artery disease. Physical examination and testing can help diagnose atrial fibrillation. Treatment often includes blood thinner, which helps prevent the strokes, and rate-control medicines that keep the heart from beating too fast, and rhythm control medicines that bring the heart rhythm back in control. Electrical cardioversion, which is a low-voltage electrical shock, is sometimes used to bring the heart beat back to normal.