Atrial fibrillation (AF) is the most common cardiac arrhythmia, followed by atrial flutter. Both arrhythmias may increase the risk of stroke. Atrial fibrillation affects about 1% to 2% of the population. 1 Patients with atrial flutter often have episodes of AF.
Direct current cardioversion (DCCV) treats atrial arrhythmias by attempting to return the patient to a normal sinus rhythm. When sinus rhythm is restored, cardiac structural changes that might have occurred as a result of AF or atrial flutter may be reversed. 2 However, patients undergoing cardioversion are at an increased risk of stroke if a thrombus is present in the left atria. This thrombus may become dislodged during the procedure. Although sinus rhythm may be restored during cardioversion, restoration of the atrial mechanical function may take several weeks, and new thrombi may form during that time. Stroke risk is significantly decreased with anticoagulation. 3,4
Current guidelines on antithrombotic therapy for AF and atrial flutter recommend that patients who are appropriate candidates for electrical cardioversion need to be properly anticoagulated for 3 to 4 weeks before and after the procedure if the duration of AF or flutter is > 48 hours or is unknown. 5 The practice of anticoagulating candidates needing cardioversion for 3 to 4 weeks before the procedure and 4 weeks after the procedure is based on the theory that it takes about 14 days for a new thrombus to firmly adhere to the atrial wall. 6 Therefore 3 to 4 weeks of anticoagulation before cardioversion will prevent new thrombi from forming and theoretically allows enough time for older thrombi to adhere to the atrial wall. Anticoagulation for 4 weeks after cardioversion will prevent new thrombi from forming in the atria during the several weeks that atrial remodeling takes place. 3,7 These practices are based on physiologic concepts and observational studies and have not been evaluated in randomized, controlled clinical trials. 7
To receive an electrical cardioversion, patients at the VA Portland Health Care System (VAPORHCS) should maintain a therapeutic international normalized ratio (INR), defined as 2.0 to 3.0, for 4 consecutive weeks. The Anticoagulation Clinic monitors patients receiving warfarin for planned DCCV at least weekly. The estimated average time for cardioversion candidates at the VAPORHCS to achieve stability on warfarin is 2 months. Prolonging the time to DCCV may expose symptomatic patients to additional discomfort, lead to further cardiac remodeling, and result in poorer outcomes.
In response to the delays attributed to time needed to achieve INR stability, the VISN 20 Pharmacy and Therapeutics (P&T) committee approved the use of dabigatran prior to cardioversion of AF in October 2011. This quality improvement (QI) project evaluated the time elapsed between initiation of anticoagulation with dabigatran vs warfarin and DCCV and the associated costs of anticoagulation before DCCV.
Methods
A single site, retrospective chart review of patients scheduled for cardioversion from November 2011 to December 2013 was conducted. This QI project was considered exempt from institutional review board approval. VAPORHCS patients aged > 18 years who initiated dabigatran or
warfarin for planned cardioversion of AF or atrial flutter were included in the study. Exclusion criteria included use of dabigatran or warfarin within 3 months before the decision to cardiovert and emergency cardioversion performed within 48 hours of symptom onset. Patients were assigned to either the dabigatran or warfarin group, based on the prescribed anticoagulant. The primary objectives were to evaluate the time elapsed from initiation of anticoagulation to planned cardioversion of AF or atrial flutter and to evaluate treatment costs associated with dabigatran vs warfarin before planned cardioversion of AF or atrial flutter. The secondary objective was to identify reasons for rescheduled or cancelled cardioversions.