Abstract 9903: Left Atrial Appendage Contractility Assessed by Speckle Tracking Transesophageal Echocardiography as a Determinant of Thrombus Formation in Patients Receiving Warfarin for Chronic Atrial Fibrillation: beyond CHADS2 and CHA2DS2-VASc Score

Abstract

Background: Establishment of optimal risk stratification is the best hope for decreasing the burden of atrial fibrillation (AF)-related thromboembolism. Left atrial appendage (LAA) thrombus is a high risk factor of embolism even in AF with warfarin. LAA contractility evaluated by LAA emptying function (EF), strain and radial velocity (RV) of LAA wall motion could contribute to blood stasis and be an important determinant of thrombus in chronic AF, especially in patients with low CHADS2 or CHA2DS2-VASc score.

Methods: Consecutive 260 chronic AF patients with warfarin were examined and divided into 2 groups according to the presence of thrombus; AF with thrombus (n=43, 69±10) and AF without thrombus (n=217, age 66±11). Each group was divided into subgroup according to CHADS2 or CHA2DS2-VASc score≤2 (low CHADS2 or CHA2DS2-VASc subgroup). LAA EF, peak strain and peak RV of LAA wall were measured using speckle tracking echocardiography. LAA volume, spontaneous echo contrast (SEC) and LAA flow velocity were measured.

Results: Seventy one % of patients with thrombus and 61% without thrombus met the target INR recommended by Japanese Circulation Society. AF with thrombus had more increased CHADS2 and CHA2DS2-VASc score and reduced LAA EF and strain compared to AF without thrombus (Table). LAA EF and strain were also reduced in low CHADS2 and CHA2DS2-VASc subgroup with thrombus. In multivariate analysis, LAA EF and strain were independent determinants of LAA thrombus. Using 20% of LAA EF as a cutoff, sensitivity and specificity for thrombus were 84% and 90%, using 5 of LAA peak strain, those values were 88% and 76%.

Conclusion: LAA EF and peak strain were more useful predictors of thrombus in chronic AF than LAA flow velocity, SEC and CHADS2 and CHA2DS2-VASc score. LAA thrombus formation may depend on LAA contractility. Thus, AF patients with reduced LAA contractility should have a strict anticoagulant therapy regardless of CHADS2 or CHA2DS2-VASc score.