Evaluation of the left atrial substrate in patients with lone atrial fibrillation using delayed-enhanced MRI: Implications for disease progression and response to catheter ablation

BACKGROUND Lone atrial fibrillation (AF) is thought to be a benign type or an early stage of the disease. OBJECTIVE This study sought to compare the left atrium (LA) substrate using delayed-enhanced magnetic resonance imaging (DE-MRI) in patients with lone AF versus those with comorbidities. METHODS Forty of 333 included patients met criteria for lone AF. All patients underwent DE-MRI to quantify atrial fibrosis as a marker for structural remodeling (SRM) and underwent catheter ablation. Based on the degree of SRM, patients were staged into 4 groups: Utah I (5% LA wall enhancement), Utah II (5% to 20%), Utah III (20% to 35%), or Utah IV (35%). RESULTS Distribution in Utah I to IV was comparable in patients with lone AF and non‐lone AF. In both groups, a number of patients showed extensive SRM. Mean enhancement (14.08 8.94 vs. 16.94 11.37) was not significantly different between the 2 groups (P .0721). In the lone AF group, catheter ablation was successful in suppressing AF in all of Utah I, 81.82% of Utah II, 62.5% of Utah III, and none of Utah IV patients. Similar results were achieved in the non‐lone AF group. Outcome after ablation was significantly dependent on the SRM of the LA (P .001). CONCLUSION The degree of LA structural remodeling as detected using DE-MRI is independent of AF type and associated comorbidities. Selecting appropriate treatment candidates based on the quality and quantity of atrial fibrosis using DE-MRI would improve procedural outcome and avoid unnecessary intervention.