PREVALENCE OF RESIDUAL LEFT ATRIAL THROMBI AMONG PATIENTS WITH ACUTE THROMBOEMBOLISM AND NEWLY RECOGNIZED AERIAL FIBRILLATION

Background: Thromboembolism related to atrial fibrillation (AF) is a m ajor cause of morbidity and mortality. Patients with acute thromboembo lism and AF are at high risk for early recurrent events. Objective: To determine the prevalence of left atrial thrombi in patients who had a cute thromboembolism and newly diagnosed AF. Patients and Methods: Adu lt inpatients with AF were screened to identify those with acute (<36 hours) systemic thromboembolism and newly recognized AF. Of 41 qualify ing patients, 31 (76%) agreed to undergo transesophageal echocardiogra phic study, including 24 with acute neurologic events and seven with p eripheral thromboembolism. A control population consisted of 88 adults with newly recognized AF without clinical thromboembolism. Results: T ransesophageal echocardiography identified left atrial thrombi in 13 ( 43%) of the 30 study patients who underwent transesophageal echocardio graphy compared with nine (10%) of 87 controls (P<.001). Spontaneous e cho contrast was identified in 27 (87%) of the study population vs 42 (48%) of controls (P<.001). The prevalence of this marker of blood sta sis did not differ between patients with left atrial thrombi without t hromboembolism (P=.69). Duration of AF, prevalence of abnormal left ve ntricular function, left atrial size, and mitral regurgitation were si milar in both groups. Conclusions: Left atrial thrombi were identified in more than 40% of patients with acute thromboembolism and newly rec ognized AF. These data suggest that a major source of recurrent thromb oembolism in this group may be residual thrombus migration. Among pati ents with AF and atrial thrombi, clinical thromboembolism seems to occ ur randomly, or is related to an unidentified process.