Left atrial appendage flow velocity predicts occult atrial fibrillation in cryptogenic stroke: a CRYPTON-ICM registry

Background: An insertable cardiac monitor (ICM) and transesophageal echocardiography (TEE) are useful for investigating potential embolic sources in cryptogenic stroke, of which atrial fibrillation (AF) is a critical risk factor for stroke recurrence. The association of left atrial appendage flow velocity (LAA-FV) on TEE with ICM-detected AF is yet to be elucidated. Methods: CRYPTON-ICM (CRYPTOgenic stroke evaluation in Nippon using ICM) is a multicenter registry of cryptogenic stroke with ICM implantation, and patients whose LAA-FV was evaluated on TEE were enrolled. The primary outcome was the detection of AF (> 2 min) on ICM. Receiver operating characteristic (ROC) curve analysis was performed to determine the optimal cut-off of LAA-FV, and factors associated with ICM-detected AF were assessed. Results: A total of 307 patients (age 66.6 ± 12.3 years; 199 males) with median follow-up of 440 (interquartile range 169–726) days were enrolled; AF was detected in 101 patients. The lower-tertile LAA-FV group had older age, more history of congestive heart failure, and higher levels of B-type natriuretic peptide (BNP) or N-terminal proBNP (all P < 0.05). On ROC analysis, LAA-FV < 37.5 cm/s predicted ICM-detected AF with sensitivity of 26.7% and specificity of 92.2%. After adjustment for covariates, the lower tertile of LAA-FV (hazard ratio [HR], 1.753 [1.017–3.021], P = 0.043) and LAA-FV < 37.5 cm/s (HR 1.987 [1.240–3.184], P = 0.004) predicted ICM-detected AF. Conclusions: LAA-FV < 37.5 cm/s predicts AF. TEE is useful not only to evaluate potential embolic sources, but also for long-term detection of AF on ICM by measuring LAA-FV in cryptogenic stroke. http://www.umin.ac.jp/ctr/ (UMIN000044366).