Uninterrupted dabigatran versus warfarin in the treatment of intracardiac thrombus in patients with non-valvular atrial fibrillation

Abstract

Atrial fibrillation (AF) is the most common cardiac arrhythmia in clinical practice and increases the risk of thrombus in the left atrial appendage (LAA) which is strongly associated with an increased risk of ischemic stroke [ 1 Hylek E.M. Anticoagulation therapy for atrial fibrillation. Semin. Thromb. Hemost. 2013; 39: 147-152 Crossref PubMed Scopus (12) Google Scholar , 2 Thambidorai S.K. Murray R.D. Parakh K. et al. Utility of transesophageal echocardiography in identification of thrombogenic milieu in patients with atrial fibrillation (an ACUTE Ancillary Study). Am. J. Cardiol. 2005; 96: 935-941 Abstract Full Text Full Text PDF PubMed Scopus (83) Google Scholar ]. Embolic strokes caused by AF are typically severe, more commonly disabling and fatal compared with strokes not associated with AF [ 1 Hylek E.M. Anticoagulation therapy for atrial fibrillation. Semin. Thromb. Hemost. 2013; 39: 147-152 Crossref PubMed Scopus (12) Google Scholar , 3 Marini C. De Santis F. Sacco S. et al. Contribution of atrial fibrillation to incidence and outcome of ischemic stroke: results from a population-based study. Stroke. 2005; 36: 1115-1119 Crossref PubMed Scopus (688) Google Scholar ]. Transesophageal echocardiography (TEE) is a sensitive method for intracardiac thrombus identification. When AF lasts for 2 days, atrial thrombi may take place in up to 14% patients on TEE examination; the prevalence of thrombus in AF patients varies from 10% to 18%, with about 90% of thrombi found in the LAA [ [2] Thambidorai S.K. Murray R.D. Parakh K. et al. Utility of transesophageal echocardiography in identification of thrombogenic milieu in patients with atrial fibrillation (an ACUTE Ancillary Study). Am. J. Cardiol. 2005; 96: 935-941 Abstract Full Text Full Text PDF PubMed Scopus (83) Google Scholar ]. The administration of vitamin K antagonists (VKA) has been the mainstay in the treatment of intracardiac thrombus with a target international normalized ratio (INR) level of 2.0 to 3.0. The use of VKA, such as warfarin, exerts excellent protective effects against thromboembolic complication but requires restrictions on food and drugs; therapeutic monitoring and dose adjustment are always needed due to its narrow therapeutic window, and high intra- and inter-patient variability [ [4] Birman-Deych E. Radford M.J. Nilasena D.S. Gage B.F. Use and effectiveness of warfarin in Medicare beneficiaries with atrial fibrillation. Stroke. 2006; 37: 1070-1074 Crossref PubMed Scopus (241) Google Scholar ]. Dabigatran etexilate, a novel oral direct thrombin inhibitor, has been approved as an alternative to warfarin for the prevention of stroke and systemic thromboembolism in patients with non-valvular AF [ [5] Connolly S.J. Ezekowitz M.D. Yusuf S. et al. Dabigatran versus warfarin in patients with atrial fibrillation. N. Engl. J. Med. 2009; 361: 1139-1151 Crossref PubMed Scopus (8682) Google Scholar ]. Recent studies indicated that dabigatran can be applied for the treatment and prevention of venous thromboembolism (VTE), with similar effects on VTE recurrence and a lower risk of hemorrhage compared with warfarin [ 6 Schulman S. Kakkar A.K. Goldhaber S.Z. et al. Treatment of acute venous thromboembolism with dabigatran or warfarin and pooled analysis. Circulation. 2014; 129: 764-772 Crossref PubMed Scopus (699) Google Scholar , 7 Schulman S. Kearon C. Kakkar A.K. et al. Extended use of dabigatran, warfarin or placebo in venous thromboembolism. N. Engl. J. Med. 2013; 368: 709-718 Crossref PubMed Scopus (791) Google Scholar ]. Dabigatran has a predictable anticoagulant effect and may be an alternative medication to warfarin for patients with non-valvular atrial fibrillation (AF) who have intracardiac thrombus.