Left atrial enlargement and clinical considerations in patients with or without a residual interatrial shunt after closure of the left atrial appendage with the WATCHMAN™-device

Abstract

Background: Interventional closure of the left atrial appendage (LAA) in patients with non-valvular atrial fibrillation, high thromboembolic and bleeding risk or bleeding history is an alternative therapeutic strategy to oral anticoagulation. It is not known if the exclusion of the LAA from the blood circulation affects the left atrial volume (LAV) and consequently its prognostic value or the circulatory performance of the heart in humans. Methods: We aimed to prospectively assess potential changes in baseline LAV, left ventricular ejection fraction (LVEF), NT-proBNP-level and the covered distance in the 6-min walk-test 6 weeks and 6 months after LAA closure with the WATCHMAN™ device. We used serial 3-dimensional transthoracic and transesophageal echocardiography to assess LAV, residual interatrial shunt and device performance in 58 consecutive patients with successful LAA closure. Results: Accurate 3D-echocardiographic data for LAV measurements were evaluable for 51 (91%) patients. Maximum LAV (LAVmax) at baseline was 102.8±30.8ml and increased significantly to 107.7±32.8ml after 6 weeks (p<0.01) and 113.5±34.2ml after 6months (p<0.01). Minimal LAV (LAVmin) increased from 76.9±29.5ml at baseline to 81.8±30.2ml after 45days (p<0.01) and 82.1±33.3ml after 6months (p<0.01). Similarly, their indexes to BSA (LAVImax and LAVImin) increased significantly, as well. Patients without a residual left-to-right interatrial shunt showed a significantly higher increase in LAVmax or LAVmin. Baseline LVEF, NT-proBNP-level or the distance covered at the 6-min walk test did not significantly change 6 weeks or 6 months after LAA closure. Conclusions: LAVmax and LAVmin increase significantly after interventional LAA closure. LA enlargement does not correlate with clinical progression of heart failure. Persistent left-to-right interatrial shunt counteracts the LA enlargement. A reduced LA compliance after exclusion of the LAA from the blood circulation with consecutive increase in LA pressure may be a potential cause of LA enlargement and warrants further investigation. Trial registration: German Clinical Trials Register ID: DRKS00010768 ; Registration Date 07.07.2016.