Blood flow in the left atrial appendage and embolic stroke in nonvalvular atrial fibrillation.

It is unclear if low flow velocity in the left atrial appendage (LAA) is a predisposing factor to stroke in patients with nonvalvular atrial fibrillation (NVAF). We investigated flow velocity in the LAA in NVAF patients in relation to a past history of stroke and other potential embolic sources. We measured and analyzed peak flow velocities into (FV-in) and out of (FV-out) the LAA in a middle portion of the LAA in 35 NVAF patients by transesophageal echocardiography (TEE). We divided the NVAF patients into 3 groups: the Eaf group had a history of embolic stroke without any other potential embolic sources; the Emulti group had other potential embolic sources, and the control group had no embolic history. FV-in and FV-out in the Eaf group (12.3 +/- 6.7 and 10.2 +/- 7.3 cm/s) were significantly lower than those in the control group (24.3 +/- 11.3 and 19.9 +/- 8.8 cm/s; multicomparison Scheffé's test, p = 0.0123 and 0.0395, respectively). The Emulti group varied in those values from less than 5 to above 35. Low flow velocity in the LAA seems to be a predisposing factor for stroke in NVAF patients without any other sources of emboli.