Abstract 264: Assessing Thromboembolic Risk In Patients Undergoing Direct Electrical Cardioversion Within 48 Hours After Onset Of Atrial Fibrillation

Abstract

Background: Direct Electrical Cardioversion (DCC) has been known to increase the risk of thromboembolism (TE) in patients with Atrial Fibrillation (AF). However, guidelines and current practices are unclear if this risk exists in patients undergoing DCC < 48 hours after AF onset. We aim to assess TE risk in these patients with and without the use of therapeutic anti-coagulation. Methods: All DCC done at Cleveland Clinic between 1996 to 2012, <48 hours after AF onset were selected from Electrophysiology database. They were divided into two groups on the basis of their anti-coagulation status. We did extensive chart review in these patients to look for outcomes of major TE complications within a month of DCC. Results: Among 567 DCC in 510 patients without therapeutic anti-coagulation, the mean (SD) CHA2DS2-VASc score was 2.34(1.66). At the time of DCC, 54% of these patients were on aspirin, while 12% were on warfarin with INR ≤1.5. There were 7 reported cerebrovascular accidents (CVAs) (1.22%) within a month after DCC. In these 7 patients, the mean (SD) CHA2DS2-VASc score was 3.57(1.27) ranging between 2 to 5. In the second group, 901 DCC were done in 733 patients who were therapeutic on warfarin (63%) or heparin (37%) at the time of DCC. Mean (SD) CHA2DS2-VASc score was 2.61(1.73). There were 2 reported (0.22%, p= 0.016) CVAs within a month after DCC. These two had CHA2D2-VASc scores of 4 and 6. Of these two patients, one was sub- therapeutic (INR=1.14) when he presented with neurological deficits 18 days after the DCC. The other patient held anticoagulation 10 days after DCC for a surgical procedure which was followed by the TE stroke a week later. The non-treated group therefore had a 5.6 times greater odds of having a thromboembolic stroke within a month of DCC (95% CI: 1.16 to 27.14) . Conclusions In patients with acute onset atrial fibrillation, odds of thromboembolic complications are over 5 times higher in patients who did not receive therapeutic anti-coagulation at the time of DCC, despite having a lower baseline stroke risk as defined by their CHA2DS2-VASc scores. In addition, the two patients in our study who did have a stroke in the therapeutically anti-coagulated group had ceased their anticoagulant prior to the stroke.