Atrial fibrillation occurs in about 20% of people with hypertrophic cardiomyopathy. In atrial fibrillation, abnormal electrical impulses cause the upper chambers of the heart (atria) to fibrillate, or quiver, sometimes resulting in irregular and rapid beating of the ventricles, the heart´s main pump. For most people, this aspect of atrial fibrillation in itself is usually not life-threatening. However, for people who have hypertrophic cardiomyopathy, atrial fibrillation can be life-threatening and make your symptoms more severe. It also increases your risk for heart failure and stroke. For these reasons, most doctors aggressively treat atrial fibrillation in people who have hypertrophic cardiomyopathy. Aggressive treatment usually means using medications to control the heart rate or rhythm and/or electrical cardioversion to return the heart to its normal rhythm. For more information, see the topic Atrial Fibrillation.
Anticoagulants often are prescribed for people who have atrial fibrillation. Anticoagulants help protect against blood clots that develop in the heart. Blood clots can be dangerous because they may break loose and travel through the bloodstream (thromboembolism), which may cause a stroke, heart attack, or blocked blood flow to an arm or leg.