Abstract 15866: Incidence and Severity of Left Atrial Scar in Older Patients With and Without Atrial Fibrillation

Abstract

Background: Atrial fibrosis or scar is considered a substrate change related to atrial fibrillation (AF); by slowing conduction and increasing heterogeneity it could provide a substrate for AF. However, it is still not known whether AF causes the profibrotic changes in the left atrial wall or simply facilitates the manifestation of an existing aging-related structural remodeling in older patients. We examined scar prevalence and severity in patients aged ≥ 75 years with and without AF to address this question. Method: Five hundred seventy one patients undergoing radio-frequency catheter ablation for AF or supraventricular tachycardia (SVT) were included in this prospective analysis and classified into 2 groups; group 1: patients with AF (n=308, 62% male, median 77.8 (75 to 91) years, 46% paroxysmal and 64% persistent AF) and group 2: patients with diagnosis of SVT (n=263, 56% male, median 80 (75 to 88) years). Left atrial (LA) scarring was determined by three-Dimensional (3D) voltage mapping. Scar was defined as an area with a bipolar voltage amplitude ≤ 0.05 mV, indistinguishable from noise. The degree of scar was described as a percentage of the LA area (mild <20%, moderate 20-60%, and severe >60%) involved. Results: Age and gender distribution was similar in both groups. Left atrial scar was detected in 172 (56%) patients in group 1 and 134 (51%) in group 2 (p=0.24). After adjusting for age and gender in multivariable logistic model, diagnosis of AF or SVT did not show to have any association with the incidence of scar (p=0.22). Based on the 3D mapping, 52(30%) patients were classified as having mild LA scarring, 88(51%) moderate scar and 32(19%) with severe scar in group 1. Distribution of scar severity in group 2 was: mild 50(37%), moderate 67(50%), and severe in 17(13%), which was similar to that of AF patients (p=0.248). Conclusion: Similar prevalence and distribution of severity of the left atrial scarring in elderly patients with and without atrial fibrillation suggest age-dependent substrate remodeling to be the major contributor of scar formation. Our results indicate that scar could facilitate atrial fibrillation in predisposed subjects only.