Thromboembolism in patients with atrial fibrillation with and without left atrial thrombus documented by transesophageal echocardiography

The incidence of cerebrovascular events (CVEs) was investigated in 95 consecutive patients with atrial fibrillation (AF) with left atrial thrombus (LAT) diagnosed by transesophageal echocardiography (TEE) and in 131 age- and sex-matched AF patients without LAT. Compared with patients without LAT, patients with LAT had a larger left atrial diameter (49 versus 44 mm, P <0.0001), a lower left ventricular ejection fraction (40% versus 50%, P <0.0001), a higher prevalence of spontaneous echocardiographic contrast (88% versus 25%, P <0.001), a reduced left atrial appendage emptying velocity (0.25 versus 0.41 cm/s, P <0.0001), and less use of antiarrhythmic drugs (61% versus 76%, P = 0.03). Before TEE, the prevalence of prior CVE was higher in LAT patients (20%) compared with patients without LAT (8%) (P = 0.01). Fifty-four of 95 LAT patients (57%) and 81 of 131 non-LAT patients (62%) were on warfarin before TEE. The incidence of prior CVE in LAT patients without warfarin (32%) was higher than that in non-LAT patients without warfarin (10%) (P = 0.02). The mortality rate in LAT patients with an international normalized ratio (INR) <2.0 (42%) was higher than that in patients without LAT and an INR <2.0 (11%) (P <0.001). Fifty-one of 95 LAT patients (54%) underwent repeat TEE before cardioversion (48 patients received warfarin therapy). The thrombus resolved in 40 of 51 patients (78%) after the first TEE. There was no significant difference in INR between the patients with persistent and resolved LAT. AF patients with persistent LAT had a higher incidence of CVE (45%) than the patients with resolved LAT (5%) (P = 0.003). We suggest that patients with LAT be treated with warfarin to maintain an INR between 2.5 and 3.5 rather than between 2.0 and 3.0 because they are at a high risk for new thromboembolism.