ATRIAL ELECTROANATOMIC REMODELLING AFTER TRANSCATHETER ATRIAL SEPTAL DEFECT CLOSURE IN ADULT PATIENTS

Abstract

Transcatheter closure is an established technique for the management of secundum type atrial septal defects (ASD) in adult patients who demonstrate clinically significant left to right shunting. Although ASD closure abolishes volume overload and reduces right-sided dimensions, a subset of patients remains at risk of atrial arrhythmias, such as atrial fibrillation, during follow-up. Atrial arrhythmias are proposed to arise from abnormalities in intra and inter-atrial conduction, resulting in the propagation of inhomogeneous impulses, and amongst patients with unrepaired ASD, p-wave duration is prolonged. In the present study, we sought to investigate the electrical and anatomic remodeling of the atria after ASD closure and its relation to atrial fibrillation. Cohort study of consecutive adult patients undergoing successful transcatheter ASD closure. Participants underwent serial echocardiography and P wave signal averaged electrocardiography (SAECG-P) at baseline and during follow up after ASD closure. Clinical events for the occurrence of atrial arrhythmia were prospectively collected. A total of 80 patients who underwent ASD closure using standard percutaneous technique constituted the study cohort. The mean age of study population was 48±16 years and 69% were female. The median ASD device size was 24 mm (range 9-40 mm). Right atrial volume, as determined by echocardiography, significantly decreased immediately post ASD closure and continued to decrease during follow-up (Figure 1). There was no significant change in the SAECG-P duration after ASD closure compared to baseline (i.e., 137 msec at one year compared to 127 msec at baseline). Atrial fibrillation occurred in 10 patients (11.3%) over a median follow up period of 12 months after ASD closure. Right atrial volume was independently associated with the occurrence of atrial fibrillation (p=0.04) in multivariate analysis adjusted for age, ASD size and right ventricular systolic pressure. Right atrial volume shows marked reduction after ASD. Despite significant positive anatomic changes in the right atrium post ASD closure, no effect on atrial conduction properties, as measured by SAECG-P duration, was observed during follow up. The absence of mechano-electrical concordance may suggest that atrial conduction delay persists despite anatomical remodeling. Furthermore, right atrial volume is independently associated with occurrence of atrial fibrillation during follow up. These findings identify important implications for atrial remodeling in patients being evaluated for ASD closure.