An older adult who was diagnosed with atrial fibrillation asks a nurse, "I feel fine. I have no symptoms at all with this heart problem, yet I am now on a blood thinner medication, which I understand can be very dangerous. Is this really necessary?" Your response is based on the understanding that:

A. The risk of stroke is very high for a person with atrial fibrillation: Atrial fibrillation causes irregular atrial contractions, leading to blood pooling and clot formation within the atria. These clots can travel to the brain and cause an embolic stroke. B. Untreated atrial fibrillation will likely cause a heart attack: Atrial fibrillation primarily increases the risk of stroke rather than myocardial infarction. While it can contribute to reduced cardiac efficiency and heart failure over time, it is not a direct cause of heart attacks. C. Atrial fibrillation can cause coronary heart disease: Coronary heart disease is usually due to atherosclerosis, not atrial fibrillation. Although both conditions may coexist, atrial fibrillation does not cause coronary plaque buildup or arterial narrowing. D. Atrial fibrillation, while initially asymptomatic, will progress and become symptomatic: Some individuals remain asymptomatic for years, while others develop symptoms. Progression is possible but not inevitable, and anticoagulation is prescribed to prevent complications regardless of symptom presence.