Should Patients with Atrial Flutter be Anticoagulated?

Abstract & Commentary

Synopsis: The risk of thromboembolism in patients with atrial flutter is higher than previously recognized.

Source: Seidl K, et al. Am J Cardiol 1998;82(5):580-583.

Although most published studies have suggested that embolism is an infrequent complication when cardioversion is performed in patients with atrial flutter, several case reports of embolization following cardioversion in patients with pure atrial flutter1,2 have been reported and therefore, many cardiologists have concluded that patients with atrial flutter should be treated as if they were afflicted with atrial fibrillation, that is, they should be anticoagulated prior to cardioversion.1,3 The risk of thromboembolism in 191 consecutive unselected patients referred for the treatment of atrial flutter was recently evaluated and reported4 in the American Journal of Cardiology. Seidl and associates found that 11 embolic events occurred in their series of 191 patients, four occurring within 48 hours of onset of the arrhythmia and three embolic events occurred following cardioversion. In a follow-up extending on average over 26 months, nine patients experienced further thromboembolic events. Hypertension was found to be the only independent predictor for an increased risk of embolization in this patient population. Seidl et al conclude that the risk of thromboembolism in patients with atrial flutter is higher than previously recognized.

COMMENT by Harold L. Karpman, MD, FACC, FACP

Over the past 15 years, numerous prospective, randomized studies have demonstrated that the incidence of thromboembolic stroke can be reduced by approximately 80% by anticoagulating patients with atrial fibrillation5 prior to cardioversion. On the other hand, several retrospective studies had demonstrated the absence of or only few embolic events,5 in patients with atrial flutter and therefore, there has been no clear cut recommendation from the 4th American College of Chest Physicians Consensus Conference on Antithrombotic Therapy, on the use of anticoagulants in patients with atrial flutter, however, the conclusion from that Conference was that "consideration should be given to treating patients with atrial flutter the same as patients with atrial fibrillation".

Seidl et al’s study evaluated thromboembolic risks of unselected patients referred to a large community hospital for treatment of chronic or recurrent atrial flutter. There were significant limitations in this study because of the relatively high frequency of cardiac disease, hypertension, diabetes mellitus and/or because a significant percentage of the patients had a long history of atrial flutter. It is therefore possible that referral bias may have resulted in selecting a patient population which had a higher risk of developing thromboembolic complications than exist in a randomly selected group and especially in that subset of patients who had developed atrial flutter within the previous few days or weeks of being seen by a physician.

Finally, it must be recognized that atrial flutter is frequently associated with intermittent atrial fibrillation even though, in the present study, atrial fibrillation occurred with similar frequency in patients whether or not they experienced thromboembolic events.

Obviously, additional studies of patients with atrial flutter who are being cardioverted will have to be performed in order to assemble a large enough data base that will permit solid, statistically significant recommendations. For the time being, it would seem to be prudent to anticoagulate patients with atrial flutter prior to cardioversion especially if they are also afflicted with cardiac disease, hypertension, diabetes mellitus, and/or recurrent atrial fibrillation full well recognizing that the administration of anticoagulants in these patients cannot at this time be considered mandatory, especially in that subset of patients who present with a history of recent onset of atrial flutter.

References

1. Black JW, et al. J Am Coll Cardiol 1992;19:314A.

2. Santigo D, et al. J Am Coll Cardiol 1994;24:159-164.

3. Manning WJ, et al. N Engl J Med 1993;328:750-755.

4. Seidl K, et al. J Am Coll Cardol 1998;82:580-583.

5. Laupacis A, et al. Chest 1995;108:3528-3585.