OBJECTIVES: Accurate sizing of the left atrial appendage (LAA) is essential when performing percutaneous LAA closure. This study aimed to compare different LAA imaging modalities and sizing methods in order to obtain successful LAA closure.

BACKGROUND: Percutaneous LAA closure is an increasingly used treatment strategy to prevent stroke in patients with atrial fibrillation. LAA sizing has typically been done by 2D-transoesophageal echocardiography (TEE).

METHODS: Patients who had a preprocedural TEE and preprocedural and postprocedural multislice CT (MSCT) were identified. Preprocedural measurements of LAA ostia and landing zones by 2D-TEE, MSCT and angiography were collected and analysed for those patients with successful LAA closure - i.e. with no contrast leakage at 3-month follow-up MSCT.

RESULTS: The study population (n=67) had a mean CHA2DS2-VASc score of 3.0 and HAS-BLED score of 2.7. Fifty-eight patients (87%) were identified to have successful LAA closure. Based on MSCT, 48 LAA sizings (83%) resulted in a correct LAA closure device size selection, whereas with 2D-TEE sizing, only 33 measurements (57%) would have resulted in a correct device size selection (p<0.01). Using adapted Bland-Altman method, MSCT-based perimeter-derived mean diameter was shown to be the best parameter to guide LAA device size selection for ‘closed-end’ devices (Amulet, WatchmanFLX), whereas the maximal diameter was the best parameter for the ‘open-end’ Watchman device.

CONCLUSIONS: Preprocedural MSCT-based LAA closure device size selection proves to be a more accurate method than conventional 2D-TEE-based sizing. Depending on the LAA closure device design, perimeter-derived mean diameter or maximal diameter could be the better sizing method.