Direct-current cardioversion (DCCV) for persistent atrial fibrillation or atrial flutter (AF) carries a risk of thromboembolic events (TEs). Therapeutic anticoagulation with warfarin is recommended for 3 to 4 weeks before and 4 weeks after DCCV to reduce TE; however, the safety of short-term anticoagulation with the novel oral anticoagulants (dabigatran and rivaroxaban) before DCCV has not been assessed. A retrospective cohort study was performed on all patients undergoing elective DCCV for AF at Northwestern Memorial Hospital from June 1, 2012 to September 30, 2013. Inclusion criteria included patients taking any of the novel oral anticoagulants for 21 to 60 days before DCCV and successful DCCV to sinus rhythm. Patients were monitored for a minimum of 60 days after DCCV to evaluate for TEs including stroke, transient ischemic attack, systemic emboli, and death. In total, 53 patients (47 men, 89%; age 65 ± 10 years, median 66) were evaluated. Agents used were dabigatran (30 patients, 57%) and rivaroxaban (23 patients, 43%) for an average of 38 ± 9 days. The mean CHADS 2 score was 1.2 ± 1.1 (score = 0, 26%; 1, 43%; 2, 17%; and >3, 13%). Eleven patients (21%) underwent a transesophageal echocardiography before their DCCV; all showed no thrombus. No patients were found to have episodes of TE within 60 days of DCCV. No patients were found to have major bleeding events. In conclusion, the use of short-term dabigatran or rivaroxaban therapy for DCCV of AF appears safe.
More than 50 years have passed since cardioversion was first executed in patients with atrial fibrillation in the mid 1950s. Since this time, much has been learned regarding the mechanism of atrial fibrillation and atrial flutter (AF), including the association with stroke and other thromboembolic events (TEs). Therapeutic anticoagulation with warfarin is recommended for 3 to 4 weeks before and 4 weeks after direct-current cardioversion (DCCV) to reduce TEs. The risk of such events is higher (5% to 7%) if anticoagulation is inadequate. However, if adequate anticoagulation is achieved, the risk of TEs is substantially lower (0.7% to 0.8%). Decades after the introduction of the vitamin K antagonist warfarin, new novel oral anticoagulants (NOACs) have appeared on the market, including dabigatran and rivaroxaban. Although studied in many post hoc analyses of large-scale clinical trials, there is a paucity of data regarding the safety of short-term anticoagulation given that many of the previously studied patients were taking NOACs for an extended length of time.
Methods
This study was approved by the Northwestern University Institutional Review Board. A standardized, retrospective, cohort study was performed on all patients undergoing elective DCCV for AF at Northwestern Memorial Hospital from June 1, 2012 to September 30, 2013. All patients had documented AF on electrocardiography previously and on the day of DCCV. Inclusion criteria included patients taking dabigatran or rivaroxaban for 21 to 60 days before DCCV and successful DCCV to sinus rhythm. Key exclusion criteria were AF due to a reversible cause, valvular disease including moderate to severe mitral stenosis, transesophageal echocardiography before 21 days of starting NOAC therapy, and the need for anticoagulation other than AF. Patients were monitored for a minimum of 60 days after DCCV to evaluate for TEs including stroke, transient ischemic attack, and death. All 53 patients (100%) were monitored and no one was lost to follow-up. TEs were defined as the presence of thrombus in patients who underwent transesophageal echocardiography before DCCV, stroke, transient ischemic episodes, or systemic embolism. More specifically, stroke was defined as the sudden onset of a focal neurologic deficit in a location consistent with the territory of a major cerebral artery, confirmed by imaging techniques. Transient ischemic attack was defined as a sudden onset of a focal neurologic symptom and/or sign lasting <24 hours. Major bleeding was defined as a reduction in the hemoglobin level of at least 20 g/L, transfusion of at least 2 units of blood, or symptomatic bleeding in a critical area or organ. Lastly, systemic embolism was defined as an acute vascular occlusion of an extremity or organ documented by means of imaging, surgery, or autopsy. Continuous and normally distributed data are reported as mean ± SD. All statistical analyses were performed using IBM SPSS, version 19 (SPSS Inc., Chicago, Illinois).
Results
Agents used were dabigatran 150 mg twice daily and rivaroxaban 20 mg/day for an average of 38 ± 9 days (range 21 to 56). Patient characteristics and prevalence of stroke risk factors are listed in Table 1 . The mean CHADS 2 score was 1.2 ± 1.1 ( Figure 1 ). Eleven patients (21%) underwent a transesophageal echocardiography before their DCCV; all showed no thrombus. Patients were monitored for a minimum of 60 days for TE as well as major bleeding. No patients were found to have TE, major bleeding events, or death.
| Variable | Median ± SD or n (%) |
|---|---|
| Age (yrs) | 65 ± 10 |
| Men | 47 (89) |
| Atrial fibrillation | 43 (81) |
| Atrial flutter | 10 (19) |
| Length of novel anticoagulant use before cardioversion (days) | 38 ± 9 |
| Hypertension | 31 (59) |
| Age >75 (yrs) | 9 (17) |
| Diabetes mellitus | 9 (17) |
| Transient ischemic attack or cerebrovascular accident | 2 (4) |
| CHADS 2 score | 1.2 ± 1.1 |
| Creatinine (mg/dl) | 1.06 ± 0.2 |
| Creatinine clearance (ml/min) | 100.5 ± 40.7 |
| Patients with transesophageal echocardiogram before cardioversion | 11 (21) |
| Use of dabigatran | 30 (57) |
| Use of rivaroxaban | 23 (43) |
| Use of 81-mg aspirin | 9 (17) |
| Use of 325-mg aspirin | 1 (2) |
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