Exercise Capacity Correlates With Left Atrial Structural Remodeling as Detected by Late Gadolinium-Enhanced Cardiac Magnetic Resonance in Patients With Atrial Fibrillation

Objectives: This study hypothesized that left atrial structural remodeling (LA-TR) correlates with exercise capacity (EC) in a cohort of patients with atrial fibrillation (AF).

Background: Late gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) imaging provides a method of assessing LA-TR in patients with AF.

Methods: A total of 145 patients (32% female, mean age 63.4 ± 11.6 years of age) with AF (66 paroxysmal, 71 persistent, 8 long-standing persistent) presenting for catheter ablation were included in the study. All patients underwent LGE-CMR imaging as well as maximal exercise test using the Bruce protocol prior to catheter ablation of AF. EC was quantified by minutes of exercise and metabolic equivalent (MET) level achieved. LA-TR was quantified from LGE-CMR imaging and classified according to the Utah classification of LA structural remodeling (Utah stage I: <10% LA wall enhancement; Utah II: 10% to <20%; Utah III: 20% to <30%; and Utah IV: >30%). AF recurrence was assessed at 1 year from the date of ablation.

Results: The average duration of exercise was 8 ± 3 min, and the mean MET achieved was 9.7 ± 3.2. METs achieved were inversely correlated with LA-TR (R² = 0.061; p = 0.003). The duration of exercise was also inversely correlated with LA-TR (R² = 0.071; p = 0.001). Both EC and LA-TR were associated with AF recurrence post ablation in univariate analysis, but only LA-TR and age were independently predictive of recurrence in multivariate analysis (p = 0.001). For every additional minute on the treadmill, subjects were 13% more likely to be free of AF 1 year post ablation (p = 0.047).

Conclusions: EC is inversely associated with LA-TR in patients with AF and is predictive of freedom from AF post-ablation.