WYNNEWOOD, PENNSYLVANIA. Dabigatran (Pradaxa) was recently approved as an anticoagulant for atrial fibrillation (AF) patients. A dosage of 150 mg twice daily was found to be superior to warfarin in the prevention of thromboembolism and stroke, while a dosage of 110 mg twice daily was found to be equivalent to warfarin at an INR between 2.0 and 3.0. The incidence of bleeding and gastrointestinal events was similar for warfarin and the 110-mg dose, but higher for the 150-mg dose, especially in patients aged 75 years or older. A group of researchers from Canada, Slovakia, Spain, Sweden and the USA now report on the use of dabigatran prior to and following cardioversion.

The study involved a subgroup of 1,270 patients who underwent cardioversion while participating in the large RE-LY trial (18,113 patients with non-valvular AF) evaluating the efficacy and safety of dabigatran compared to warfarin. The 1,270 patients underwent a total of 1983 cardioversions, 84% of which were electrical. The number of cardioversions performed in the three study groups – dabigatran, 110 mg twice daily (D110), dabigatran, 150 mg twice daily (D150), and warfarin to achieve an INR of 2.0 to 3.0 were similar at 647, 672, and 664.

Transesophageal echocardiography (TEE) was performed in 21% of patients and left atrial appendage thrombi were found in 1.8% of patients in the D110 group, 1.2% in the D150 group, and 1.1% in the warfarin group. The incidence of stroke and systemic embolism within 30 days of cardioversion was not significantly different in the three groups and neither was the incidence of major bleeding.

NOTE: The reason that the differences in the incidence of stroke and bleeding events are not statistically significant relates to the fact that the total number of patients affected was very small (only 11 cardioversions were followed by a stroke or thromboembolism, and only 19 were followed by major bleeding).

There was no difference in the incidence of stroke and systemic embolism between patients who had a TEE prior to cardioversion and those who had not, likely indicating that TEE may not be necessary in patients who have been adequately anticoagulated for at least 3 weeks prior to cardioversion. NOTE: This study was funded by Boehringer Ingelheim, the manufacturer of dabigatran, and all the authors had received grants or consulting fees from the company.

Nagarakanti, R, et al. Dabigatran versus warfarin in patients with atrial fibrillation: an analysis of patients undergoing cardioversion. Circulation, Vol. 123, January 18, 2011, pp. 131-36

Editor's comment: It would appear that dabigatran is pretty well equivalent to warfarin when it comes to protection against cardioversion-related thromboembolic and stroke events associated with electrical cardioversion. The fact that no INR monitoring is required in the 3 weeks leading up to cardioversion and the 4 weeks following would make dabigatran a convenient and cost-effective alternative to warfarin.