Radiofrequency and Cryoablation of the Posterior Wall of the Left Atrium

This study compares two procedures — radiofrequency ablation and cryoablation — for treating a specific area of the heart (the posterior wall) in patients with persistent atrial fibrillation (an irregular heart rhythm that hasn't responded to medications). Both procedures use different forms of energy to scar heart tissue and stop irregular electrical signals. **You may be eligible if...** - You are between 18 and 80 years old - You have persistent or long-standing persistent atrial fibrillation that has not responded to antiarrhythmic medications - You have consented to participate **You may NOT be eligible if...** - You have another heart condition requiring surgery - You have had previous open-heart surgery - You have blood clotting disorders or bone marrow disease - Your heart pumping function is below 40% - You have poorly controlled blood pressure or kidney problems - Your mitral valve has significant damage - You are unlikely to return for follow-up visits Talk to your doctor to see if this trial is right for you.