Efficacy of Low-Dose Isoproterenol Infusion for the Exclusion of a Left Atrial Appendage Thrombus in Patients With Dense Spontaneous Echo Contrast Caused by Atrial Fibrillation

• Published in: Circulation Journal 2023/11/24, Vol.87(12), pp.1800-1808
• Main Authors: Machino-Ohtsuka, Tomoko, Minami, Kentaro, Yamasaki, Hiro, Nakatsukasa, Tomofumi, Kawamatsu, Naoto, Sato, Kimi, Yamamoto, Masayoshi, Maruo, Kazushi, Ishizu, Tomoko, Kawakami, Yasushi, Ieda, Masaki
• Format: Article
• Language: English
• Subjects: Atrial Appendage - diagnostic imaging; Atrial fibrillation; Atrial Fibrillation - complications; Atrial Fibrillation - drug therapy; Echocardiography, Transesophageal - methods; Heart Diseases - etiology; Humans; Isoproterenol; Left atrial appendage; Spontaneous echo contrast; Stroke Volume; Thrombosis - diagnostic imaging; Thrombosis - etiology; Transesophageal echocardiography; Ventricular Function, Left
• ISSN: 1346-9843; 1347-4820; 1347-4820
• DOI: 10.1253/circj.CJ-23-0271

Background: In patients with atrial fibrillation (AF) and severe blood stasis in the left atrial appendage (LAA), dense spontaneous echo contrast (SEC) disturbs the distinct visualization of the LAA interior, thus making thrombus diagnosis inconclusive. We aimed to prospectively assess the efficacy and safety of a protocol for a low-dose isoproterenol (ISP) infusion to reduce SEC to exclude an LAA thrombus.Methods and Results: We enrolled 17 patients with AF and dense SEC (Grade 4 or sludge). ISP was infused with gradually increasing doses of 0.01, 0.02, and 0.03 μg/kg/min at 3-min intervals. After increasing the dose to 0.03 μg/kg/min for 3 min, or when the LAA interior was visible, the infusion was terminated. We reassessed the SEC grade, presence of an LAA thrombus, LAA function, and left ventricular ejection fraction (LVEF) within 1 min of ISP termination. Compared with baseline, ISP significantly increased LAA flow velocity, the LAA emptying fraction, LAA wall velocities, and LVEF (all P