An arrhythmia is an abnormal heart rhythm. Atrial fibrillation is the most common type of irregular heart rhythm in the United States. It originates in the atria, the heart's two upper chambers, and increases the risk of a stroke.
Hypertrophic cardiomyopathy (HCM) causes thickening of the walls of the heart, which affects the ability of the heart to effectively pump blood flow to the rest of the body.
