Abstract TP227: Three-dimensional Analysis Of Flow, Volume And Ejection Fraction Of The Left Atrial Appendage In Acute Stroke Patients With Paroxysmal Atrial Fibrillation

Abstract

Background and objective: Decreased peak flow velocity (PFV) of the left atrial appendage (LAA) measured by transesophageal echocardiography (TEE) was reported to be associated with atrial fibrillation (AF) and thrombus formation in LAA. This study aimed to elucidate the association between flow, volume and ejection fraction (EF) of LAA measured by real-time three dimensional TEE (3D-TEE) and the presence of paroxysmal atrial fibrillation (PAF) in acute stroke. Methods: 3D-TEE was performed using an iE 33 Ultrasound Machine and X7-2t TEE transducer (Philips Healthcare) in acute stroke patients with sinus rhythm at the examination. Patients were divided into those with a history or later documentation of PAF (PAF group) and others (sinus group). PFV was measured by pulse Doppler and LAA volume was measured off-line using QLAB software. LAA volume was measured twice before p wave (maximum LAA volume) and after p wave (minimum LAA volume) to calculate EF of LAA. Results: Of a total 97 patients (26 women, 72.7±10.6 years), 20 were allocated to the PAF group and the remaining 77 to the sinus group. LAA volume and EF were correlated with PFV (r=0.378, p=0.0002 and r = 0.374, p=0.0002; respectively). Patients in the PAF group had lower PFV (39.0cm/s, 29.4-57.0 vs. 63.9cm/s, 38.3-81.8, p=0.0006), larger LAA volume (median 7.6ml, IQR 3.6-10.45 vs. 2.3ml, 1.6-6.2, p=0.0033) and lower EF (38.2%, 21.4-49.8 vs. 58.1%, 44.1-71.8, p=0.0006) than those in the sinus group. Using receiver operating characteristic curve analysis, the optimal cutoff of PFV to predict PAF patients was ≤39cm/s, with a sensitivity of 58%, a specificity of 89%, and a c-statistic of 0.756. The cutoff of LAA volume was ≥7.5ml, with a sensitivity of 55%, a specificity of 84%, and a c-statistic of 0.714. The cutoff of EF was ≤47.9%, with a sensitivity of 75%, a specificity of 75%, and a c-statistic of 0.751. Using the combination of LAA volume ≥7.5ml or EF ≤47.9%, patients with PAF were detected with a sensitivity of 85% and a specificity of 67%. Conclusions: Because EF of LAA was associated with FV, it is a promising marker of LAA function. LAA enlargement and reduced LAA contraction, measured by 3-dimensional techniques, in addition to lower FV may help us to detect those with PAF in acute stroke.