Abstract
Atrial fibrillation (AF) is the most common form of tachyarrhythmia and carries a significant risk of serious thromboembolic complications. Anticoagulation is used for long‐term thromboprophylaxis and for short‐term management in a number of clinical situations, among which is the medical or electrical cardioversion of AF to sinus rhythm. Current guidelines recommend prompt cardioversion with heparin cover for AF of < 48 h duration, and several weeks of warfarin therapy prior to cardioversion when the duration of disease is longer. Recent animal and human studies, however, have shown that swifter cardioversion is likely to be more successful in achieving sinus rhythm and in reducing the risk of recurrence of AF. Other observations have demonstrated that thrombi can develop within a few hours of the development of AF. These considerations suggest that cardioversion should be carried out as early as possible in all cases, and that the most sensitive means of detecting atrial thrombi, currently transesophageal echocardiography (TEE), should be used to screen all patients prior to cardioversion. Within this context, there is growing interest in the use of low‐molecular‐weight heparin (LMWH) as an anticoagulant therapy in AF. Compared with unfractionated heparin, LMWH therapy does not involve prolonged intravenous administration, hospitalization, or laboratory monitoring; LMWH therefore has the potential to greatly simplify anticoagulation therapy for AF, especially pericar‐dioversion. Recent studies have demonstrated that LMWH can be used safely and effectively in place of unfractionated heparin for acute treatment at the onset of AF and during early cardioversion. For example, in patients with AF, a strategy of immediate administration of dalteparin (100 IU/kg s.c. twice daily) continued for 11 days, combined with early TEE and immediate cardioversion in patients with no thrombus, resulted in sinus rhythm in 74% of patients after a median of 7 days. Low‐molecular‐weight heparin therapy may also find a role perioperatively and in selected patients, notably those with warfarin intolerance, as a replacement for warfarin following cardioversion. Controlled clinical studies are still required, however, to establish a firm, evidence‐based foundation for the use of LMWHs in AF.
Keywords: atrial fibrillation, cardioversion, anticoagulation, low‐molecular‐weight heparin, warfarin, transesophageal echocardiography
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Reference
- 1. Prystowski EN: Management of atrial fibrillation: Therapeutic options and clinical decisions. Am J Cardiol 2000; 85: 3D–11D [DOI] [PubMed] [Google Scholar]
- 2. Roijer A, Eskilsson J, Olsson B: Transoesophageal echocardiography‐guided cardioversion of atrial fibrillation or flutter. Selection of a low‐risk group for immediate cardioversion. Eur Heart J 2000; 21: 837–847 [DOI] [PubMed] [Google Scholar]
- 3. Reiffel JA: Drug choices in the treatment of atrial fibrillation. Am J Cardiol 2000; 85: 12D–19D [DOI] [PubMed] [Google Scholar]
- 4. Thomson R, Parkin D, Eccles M, Sudlow M, Robinson A: Decision analysis and guidelines for anticoagulant therapy to prevent stroke in patients with atrial fibrillation. Lancet 2000; 355: 956–962 [DOI] [PubMed] [Google Scholar]
- 5. Merli GJ: Low‐molecular‐weight heparins versus unfractionated heparin in the treatment of deep vein thrombosis and pulmonary embohsm. Am J Phys Med Rehabil 2000; 79 (5suppl): S9–S16 [PubMed] [Google Scholar]
- 6. Laupacis A, Albers G, Dalen J, Dunn M, Feinberg W, Jacobson A: Fourth ACCP Consensus Conference on Antithrombotic Therapy. Antithrombotic therapy in atrial fibrillation. Chest 1995; 108: 352S–359S [DOI] [PubMed] [Google Scholar]
- 7. Prystowski EN, Benson DW Jr, Fuster V, Hart RG, Kay GN, Myerburg RJ, Naccarelli GV, Wyse DG: Management of patients with atrial fibrillation. A statement for healthcare professionals from the Subcommittee on Electrocardiography and Electrophysiology, American Heart Association. Circulation 1996; 93: 1262–1277 [DOI] [PubMed] [Google Scholar]
- 8. Black IW, Fatkin D, Sagar KB, Khandheria BK, Leung DY, Galloway JM, Fenenley MP, Walsh WF, Grimm RA, Stollberger C, Verhorst PMJ, Klein AL: Exclusion of atrial thrombus by transesophageal echocardiography does not preclude embolism after cardioversion of atrial fibrillation. A multicenter study. Circulation 1994; 89: 2509–2513 [DOI] [PubMed] [Google Scholar]
- 9. Wijffels MC, Kirchhof CJ, Dorland R: Atrial fibrillation begets atrial fibrillation. A study in awake chronically instrumented goats. Circulation 1995; 92: 1954–1968 [DOI] [PubMed] [Google Scholar]
- 10. Rodriguez LM, Timmermans C, Wellens HJ: Are electrophysiological changes induced by longer lasting atrial fibrillation reversible? Observations using the atrial defibrillator. Circulation 1999; 100: 113–116 [DOI] [PubMed] [Google Scholar]
- 11. Main ML, Klein AL: Cardioversion in atrial fibrillation: Indications, thromboembolic prophylaxis, and role of transesophageal echocardiography. J Thromb Thrombolysis 1999; 7: 53–59 [DOI] [PubMed] [Google Scholar]
- 12. Steering and Publications Committees of the ACUTE Study : Design of a clinical trial for the assessment of cardioversion using transoesophageal echocardiography (The Acute Multicenter Study). Am J Cardiol 1998; 81: 877–883 [PubMed] [Google Scholar]
- 13. Bechtold H, Sawitzki D, Gunzenhauser D, Janssen D: Anticoagulation with low molecular weight heparin dalteparin in atrial fibrillation. Eur Heart J 2000; 21 (suppl): 8 [DOI] [PubMed] [Google Scholar]