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.