Atrial fibrillation is an irregular heartbeat that increases the risk of stroke and heart disease. Signs include dizziness, weakness, and fatigue. Treatment involves medication and lifestyle changes, and sometimes procedures such as cardioversion, ablation, pacemakers, or surgery.
Normally, your heart contracts and relaxes to a regular beat. In atrial fibrillation, the upper chambers of the heart (the atria) beat irregularly (quiver) instead of beating effectively to move blood into the ventricles. About 15–20 percent of people who have strokes have this heart arrhythmia.