Lesion Formation With Pulsed Field Versus Cryobaloon Ablation as Assessed by Cardiac Magnetic Resoncance

This trial is comparing two types of catheter ablation procedures used to treat atrial fibrillation (an irregular heart rhythm): pulsed field ablation (a newer technique using electrical pulses) versus cryoballoon ablation (using freezing). The study uses cardiac MRI to compare how much scar tissue each method creates in the heart. **You may be eligible if...** - You have atrial fibrillation and are scheduled for your first ablation procedure - You are 18 or older **You may NOT be eligible if...** - You are under 18 - You have long-standing persistent atrial fibrillation - You have had a prior ablation procedure in the left side of your heart - You are pregnant or breastfeeding - You have a significantly weakened heart (reduced ejection fraction) - Your kidney function is severely reduced (GFR below 30%) - Your BMI is above 35 - Your left atrium (upper heart chamber) is enlarged (more than 55 mm) - You have an implanted cardiac device (e.g., pacemaker) Talk to your doctor to see if this trial is right for you.