EXercise Cardiac Magnetic Resonance Assessment of Left Atrial Mechanics Following Ablation

Inclusion Criteria: * Age ≥18 years * Diagnosis of paroxysmal AF * Left ventricular ejection fraction ≥50% * Scheduled for catheter ablation * Able to speak, hear, and read English * Willing and able to provide informed consent Exclusion Criteria: * Persistent or permanent AF * Prior ablation (catheter based or surgical) for AF * Significant sinus node dysfunction * Implanted pacemaker or defibrillator * Contraindication to or inability to complete cardiovascular magnetic resonance study * Contraindication to or inability to complete exercise testing * Chronic kidney disease with estimated glomerular filtration rate \<30 mL/min/1.73m2 * Severe left ventricular hypertrophy * Unrelated cardiomyopathy that is expected to limit exercise capacity, including but not limited to: * Hypertrophic cardiomyopathy * Cardiac amyloidosis * Constrictive pericarditis * Pulmonary arterial hypertension * Prior cardiac surgery * Active pregnancy