Usefulness of transoesophageal echocardiography in selection of low risk patients with atrial fibriliation for immediate cardioversion

ABSTRACT

Despite exclusion of left atrial thrombi by transoesophageal echocardiography [TEE], cardioversion related thromboembolism has been reported in atrial fibrillation [A.F.]. The aim of this work is to define low risk group of patients with A.F. for cardioversion without previous anticoagulation. Patients were selected for immediate cardioversion if there were no thrombi, no spontaneous echo contrast, and the outflow velocity of left atrial appendage [LAA] was >/= 0.25 cm/sec. on TEE. Sixty patients with A.F. lasting more than 2 days without previous anticoagulation were examined with TEE and included in this study. Patients who are eligible for immediate cardioversion after TEE were anticoagulated with I.V. heparin together with warfarin prior to cardioversion. Heparin was continued until the patient has reached the therapeutic prothrombin value then D.C. shock was given to convert A.F. into sinus rhythm. Based on TEE findings, the patients were divided into two groups- Immediate cardioversion, group A with mean age of 36.6 +/- 8.3 years [n=42] and conventional warfarin treatment before cardioversion, group B with mean age of 65.4 +/- 6.8 years [n=18].We found non significant difference between two groups regarding the aetiology of A.F. except hypertension which was more common in group B [p<0.05]. Echocardiography revealed thrombi in 5 patients in group B representing 8.3% of all TEE examined patients. Left atrial dimension [LAD] was significantly larger, fractional shortening was lower, impaired L.V. function was more common and LAA outflow and inflow velocities were lower in group B compared to group A [p<0.001]. Age, duration of A.F. and impaired L.V. function were independent negative predictors for immediate cardioversion. No thromboembolic events occurred at or after cardioversion in any of the patients. One-month follow-up maintenance of sinus rhythm was found in 3 1/42 [73.6%] patients in group A compared to 5/18 [27.8%] patients in group B [p<0.01]. After using these TEE exclusion criteria [No thrombi, No spontaneous echo contrast and LAA outflow velocity >/= 25 cm/sec.] immediate cardioversion can safely be performed in about 88% of patients with A.F. lasting more than 48 hours without incrased risk of thromboembolism. These patients maintained sinus rhythm significantly better after one month compared to patients with conventional warfarin therapy before cardioversion