What is the primary treatment approach for atrial fibrillation if the onset is more than 48 hours?

In cases of atrial fibrillation where the onset has been more than 48 hours, the primary treatment approach focuses on rate control and anticoagulation. This recommendation is based on the risk of thrombus formation in the left atrial appendage during prolonged atrial fibrillation episodes.

When atrial fibrillation persists beyond 48 hours, there is an increased risk of stroke if the rhythm is restored to normal sinus rhythm without appropriate anticoagulation. Rate control aims to manage the heart rate, ensuring that the patient remains stable while anticoagulation reduces the risk of thromboembolic events. Typically, anticoagulation is initiated before any attempts at cardioversion, especially if the duration of fibrillation is uncertain.

Immediate cardioversion, of a synchronized type, is usually reserved for patients presenting with severe symptoms or hemodynamic instability rather than those with a longer duration of atrial fibrillation. Aspirin therapy alone does not provide adequate anticoagulation for stroke prevention in this situation, particularly because it is less effective in preventing thromboembolic events compared to other anticoagulant options. Therefore, the combination of rate control and anticoagulation is the established and safest approach in managing atrial fibrillation of this duration.