In recent years, nonrheumatic atrial fibrillation (AF) has received much attention because it is associated with an increased risk of thromboembolic complications. The incidence of ischemic stroke is about five times higher in patients with nonrheumatic AF than is the case in patients with sinus rhythm. This increased risk of stroke was presumably due to cardiogenic embolism. With the advent of transesophageal echocardiography (TEE), cardiac source of emboli, particularly the left atrial appendage (LAA) thrombi now can be detected with much greater sensitivity. Jordan et al reported that LAA thrombus could be found in 34 of 40 patients (85 percent) with mitral stenosis. Because of the high incidence of thrombus formation in LAA, the LAA function and its blood flow have recently come under increased scrutiny. Few studies, however, have dealt with the LAA function in patients with nonrheumatic AF. The present study was directed at assessing the LAA function and its blood flow by means of TEE in patients with nonrheumatic AF and identified the subgroup of patients with higher incidence of LAA spontaneous echocardiographic contrast (SEC) or thrombus formation. canada health and care mall
From June 1992 to February 1993, 33 patients diagnosed as having chronic nonrheumatic AF in the outpatient clinics or inpatient wards at National Taiwan University Hospital were enrolled in this study. Chronic nonrheumatic AF was diagnosed in patients found to have AF by conventional electrocardiography on at least 2 occasions separated by at least 1 month, and no clinical or echocardiographic evidences of mitral stenosis, severe mitral regurgitation, or mitral valve prosthesis. The duration of AF was taken as the interval between its first electrocardiographic diagnosis and the performance of TEE. One of the 33 patients was excluded because of failure of gastroscope insertion and the other 3 were excluded due to poor image quality. The remaining 29 patients tolerated the procedure well, and no complications were noted. These 29 patients (16 men and 13 women; mean age, 63.8 years; range, 38 to 77 years) formed the basis of this study. The prevalence of the different etiologies was as follows: hypertensive cardiovascular disease (13 patients); coronary artery disease (5 patients); chronic lung disease (1 patient); thyrotoxicosis (1 patient); sick sinus syndrome (1 patient); and lone AF (8 patients). A detailed history review was done for all patients to identify the use of oral anticoagulant or antiplatelet agents.