A new study, published in JAMA Network Open, indicates that patients with atrial flutter have a lower incidence of stroke than patients with atrial fibrillation who have the same CHA2DS2-VASc score. Given current European guidelines advise that patients with atrial flutter receive the same management, in terms of reducing the risk of stroke, this finding has implications for the use of anticoagulation in patients with atrial flutter—i.e. whether anticoagulation should be prescribed at the same level of CHA2DS2-VASc score as for patients with atrial fibrillation.
Authors Yu-Sheng Lin (Division of Cardiology, Depart of Internal Medicine, Chang Gung Memorial Hospital, Chiay, Taiwan) and others report that atrial flutter is similar to atrial fibrillation “in that its incidence increases with age and it contributes to heart failure, stroke, and all-cause mortality”. As result of this, they add, “the pharmacological management of atrial flutter is usually considered to be the same as for atrial fibrillation, especially preventing thromboembolic events”. However, Lin et al note that, despite sharing common risk factors, atrial flutter and atrial fibrillation are associated with different clinical outcomes. “On the basis of the distinct underlying electrophysiological mechanisms and myocardial substrates of atrial flutter and atrial fibrillation, the incidence of ischaemic stroke, hospitalisation for heart failure, and all-cause mortality would be expected to be different levels of CHA2DS2-VASc score [used to assess the risk of all three of these outcomes],” the authors comment. Therefore, the aim of their study was to evaluate this hypothesis.
Using data from the Taiwan National Hospital Insurance Research Database, Lin et al identified 219,416 age- and sex-matched individuals. Of these, 188,811 had atrial fibrillation, 6,121 had atrial flutter, and 24,484 had neither (the control group).
Overall, the incidence densities (events per 100 person years) of ischaemic stroke were significantly greater in the atrial fibrillation group compared with the atrial flutter and control groups. Furthermore, while increasing CHA2DS2-VASc score was associated with increasing incidence densities of ischaemic stroke in all three groups, the incidence of stroke associated with a specific level of CHA2DS2-VASc score differed depending on whether the patient had atrial fibrillation or atrial flutter. The authors comment: “The incidence densities of ischaemic stroke at a CHA2DS2-VASc score of one in the atrial fibrillation cohort was similar to that at a CHA2DS2-VASc score of two in the atrial flutter cohort. Moreover, the incidence densities of ischaemic stroke at a CHA2DS2-VASc score of two in the atrial fibrillation cohort was similar to that at a CHA2DS2-VASc score of four in the atrial flutter group.”
At all levels of CHA2DS2-VASc score, the incidence densities of ischaemic stroke were significantly greater in the atrial fibrillation group compared with the control group but they were only significantly higher in the atrial flutter group (vs. the control group) at CHA2DS2-VASc scores five to nine. Apart from CHA2DS2-VASc score zero, the incidence densities of ischaemic stroke were significantly higher in the atrial fibrillation group vs. the atrial flutter group at all score levels.
Lin et al comment that current European guidelines recommend that anticoagulation is prescribed at CHA2DS2-VASc score two or higher (and considered in those with a score of one) in both patients with atrial flutter and those with atrial fibrillation.
Lin told Cardiovascular News: “From this nationwide cohort study, using data from Taiwan’s National Health Insurance Research Database, we found that the incidences of ischaemic stroke in patients with atrial flutter and atrial fibrillation at the same level of CHA2DS2-VASc score were different. During study analysis, we found that 8–10% patients with isolated atrial flutter received anticoagulation therapy and this figure was lower than that in patients with atrial fibrillation. Such prescription behaviour of physicians in clinical practice could be attributed to the belief of low incidence of ischaemic stroke in patients with atrial flutter compared to those with atrial fibrillation.
In fact, according to our findings, this phenomenon make sense. Therefore, our study suggests that further research should be performed to re-evaluate the net clinical benefit of oral anticoagulants in patients with atrial flutter as currently recommended according to level of the CHA2DS2-VASc score.”