A Novel Finding: The Left Atrial Substrate Property Is a Determinant of Left Atrial Compliance Changes after Catheter Ablation of Atrial Fibrillation

Introduction: The impact of the left atrial (LA) substrate property on the LA compliance before and after pulmonary vein isolation (PVI) is not clear. Methods: The study consisted of 10 patients (age 53 ± 14) who underwent Catheter ablation for atrial fibrillation. All patients received hemodynamic measurements of LA pressure and compliance. Electroanatomic LA bipolar voltage mapping was performed. The measurements were obtained before and after the PVI. Results: Before ablation, the LA pressure and compliance did not correlate with the LA mean voltage. After ablation (fluid load of 2200±540 cc and mean duration of 2.5 hours), the LA compliance (5.4 ± 3.1 cm3/mmHg) increased in 4 patients (40%) and decreased or no change in 6 others (60%). The patients with increased compliance had a higher voltage (2.3 ±0.5 vs. 1.4±0.2mV, P=0.03) and a smaller scar area (<0.5mV, 10.3 ± 8.5 vs. 32.9±9.2%, p=0.005). There was a linear relationship between the LA mean voltage and LA compliance after PVI. Conclusion: Catheter ablation and fluid loading unmask different hemodynamic responses of the LA. In patients with less atrial remodeling (higher voltage, fewer scar), PVI immediately improved the LA compliance. In patients with more atrial remodeling, the LA compliance worsened after ablation with fluid loading.