Prophylactic anticoagulation of atrial flutter prior to cardioversion: meeting the "burden of proof"

Prevalence of auricular thrombosis before atrial flutter cardioversion: a 17-year transoesophageal echocardiographic study

AIMS

Prevalence of left appendage thrombosis ranges from 6 to 18% in persistent atrial fibrillation (AF). Few and low sample size studies have assessed left and right atrial thrombosis in persistent atrial flutter (AFL) and a wide variety of frequencies, from 1 to 21%, has been reported. The aim of this study was to evaluate the prevalence of atrial appendage thrombosis in a large population of patients undergoing transoesophageal echocardiography (TEE)-guided cardioversion (CV) for recent AFL onset and compare it with AF.

METHODS AND RESULTS

From 1999 to September 2014, we collected data of 1081 patients to CV: 877 affected by AF (81.1%) and 204 by AFL (18.9%). The presence of auricular thrombosis was evaluated by TEE in AF or AFL persisting for more than 48 h. The presence of appendage thrombosis, Doppler emptying velocities, and severe spontaneous echo contrast (SEC) was studied. The overall prevalence of atrial thrombosis was 9.62% (104/1081). Frequency of atrial thrombosis in AFL patients was 6.4% (13/204) vs. 10.5% among AF (92/877), P = 0.074. Comparing the two appendages, frequency of left atrial appendage thrombosis was in AFL 5.9% (12/204) vs. 9.9% (87/877) in the AF group, P = 0.07. Right atrial appendage thrombosis was present in 0.5% (1/204) in the AFL group vs. 0.8% (7/877) in the AF group, P = 0.64. Moderate to severe SEC (3+/4+) was present in 28% of AFL patients (57/204) vs. 35% of AF patients (307/877), P = 0.05.

CONCLUSION

Auricular thrombosis is not an infrequent finding in AFL before CV. Our study suggests the use of TEE screening in AFL, as well as in AF, when patients arrive to clinical attention after more than 48 h from arrhythmia onset.

Atrial flutter and the risk of thromboembolism: a systematic review and meta-analysis

PURPOSE

We conducted a systematic review and meta-analysis of observational studies to assess the risk of thromboembolism associated with atrial flutter.

METHODS

MEDLINE, EMBASE, bibliographies, and consultation with clinical experts were used to identify studies that report the risk of thromboembolism associated with attempted cardioversion and longer-term risk in chronic atrial flutter. The review process and data extraction were performed by two reviewers. Study event rates were assessed graphically, and a chi-squared test was used to assess heterogeneity across studies. Meta-regression with weighted logistic regression was used to assess the association between study-level clinical factors and reported thromboembolic event rates.

RESULTS

We found 13 studies that reported the risk of thromboembolism associated with cardioversion of atrial flutter. Short-term event rates ranged from 0% to 7.3%. A chi-squared test for heterogeneity was significant (P < 0.001), so results were not pooled. Instead, a meta-regression analysis was performed, which partly explained the heterogeneity across studies. Studies were more likely to report high event rates when they included patients with a prior history of thromboembolism, and to report lower event rates when at least some patients were anticoagulated or if patients underwent echocardiography before cardioversion. Four studies reported the longer-term risk of thromboembolism, and these suggest a yearly event rate of approximately 3% with sustained atrial flutter.

CONCLUSION

These findings suggest that atrial flutter is indeed associated with an increased risk of thromboembolism, and that clinical factors account for the low event rates reported in some studies.