Atrial Structural Remodeling in Patients With Atrial Fibrillation Is a Diffuse Fibrotic Process: Evidence From High-Density Voltage Mapping and Atrial Biopsy

Background Low-voltage areas (LVAs) in the atria of patients with atrial fibrillation are considered local fibrosis. We hypothesized that voltage reduction in the atria is a diffuse process associated with fibrosis and that the presence of LVAs reflects a global voltage reduction. Methods and Results We examined 140 patients with atrial fibrillation and 13 patients with a left accessory pathway (controls). High-density bipolar voltage mapping was performed using a grid-mapping catheter during high right atrial pacing. Global left atrial (LA) voltage (V ) in the whole LA and regional LA voltage (V ) in 6 anatomic regions were evaluated with the mean of the highest voltage at a sampling density of 1 cm . Patients with atrial fibrillation were categorized into quartiles by V . LVAs were evaluated at voltage cutoffs of 0.1, 0.5, 1.0, and 1.5 mV. Twenty-eight patients with atrial fibrillation also underwent right atrial septum biopsy, and the fibrosis extent was quantified. Voltage at the biopsy site (V ) was recorded. V results by category were Q1 (