Thrombolytic action of dabigatran in patients with acute pre-existing atrial thrombus

THROMBOSIS OF LEFT ATRIAL APPENDAGE DURING THERAPY WITH DIRECT ORAL ANTICOAGULANT. CLINICAL CASE

The article presents a clinical observation of the left atrial appendage thrombosis in a 51-year-old female patient with a paroxysmal form of nonvalvular atrial fibrillation which occurred despite long-term anticoagulant therapy with apixaban in a full dose (5 mg b.i.d.), and the patient’s management. The patient was admitted with recurrent symptomatic paroxysm for more than 48 hours, because of which, in accordance with the recommendations, transesophageal echocardiography was performed before an emergency rhythm restoration. Thrombus in the left atrial appendage 0.5×1.03 cm in size was detected. It was decided to refrain from the immediate restoration of the rhythm due to the very high risk of thromboembolic complications. In connection with the categorical refusal of the patient from warfarin, it was decided to replace apixaban with another direct oral anticoagulant – dabigatran 150 mg bid for a period of 4 weeks followed by performing a control transesophageal echocardiographic study. As a result, no thrombus was found on control echocardiography. The particularity of this observation is concomitant hypertrophic cardiomyopathy and diabetes mellitus type 1 in this patient.

Three-dimensional Transesophageal Echocardiography Demonstration of Left Atrial Appendage Echocontrast Regression after 6 Months Therapy with Dabigatran and not with Warfarin

While warfarin therapy is efficacious in treating left atrial (LA) thrombus formation in patients with nonvalvular atrial fibrillation (AF), it does not affect red cell aggregation in vitro or LA spontaneous echo-contrast in patients. In this patient with left ventricular (LV) dysfunction secondary to AF, we observed the disappearance of dense echo-contrast in the atrial appendage after therapy with dabigatran and not with well-controlled warfarin. This allowed us to analyze accurately the appendage with three-dimensional (3D) transesophageal echocardiography (TEE) excluding thrombi and to perform electrical cardioversion to obtain a significant improvement of LV function. This case demonstrates the capability of dabigatran and not of warfarin in reducing the intense spontaneous echocontrast in atrial appendage and the ability of 3D TEE in analyzing accurately the appendage, excluding thrombi to safely perform cardioversion.

Thrombus formation in left atrium on dabigatran therapy

Dabigatran is a direct thrombin inhibitor, approved in the United States for stroke prevention in nonvalvular atrial fibrillation and prevention and treatment of thromboembolism. It has been also used in patients with documented left atrial thrombus, where treatment with dabigatran effectively led to thrombus resolution. We present a rare case of left atrial thrombus formation in a patient with chronic atrial fibrillation being treated with dabigatran 150 mg twice a day. The patient presented with multiple embolic strokes. There are only three such cases reported in the literature till date, all of whom had thrombus in the left atrium. The possible mechanisms of dabigatran failure include compensatory increase in upstream coagulation factors due to single level downstream blockade of thrombin, lack of inhibition of all available thrombin, and lack of monitoring measures that can be implemented in common clinical laboratories that lead to failure to assess adherence, which in turn can lead to dabigatran failure.