"The study strongly supports the recommendations that anticoagulation be used post conversion," said Peter Block, MD, FACC.

A large retrospective study published July 10 in the Journal of the American College of Cardiology  supports guidelines calling for effective anticoagulation therapy in acute atrial fibrillation (AFib) patients with risk factors for stroke who undergo cardioversion. While the risk of stroke or other thromboembolic events is generally low in patients with acute AFib, over the short term, risks for stroke or other adverse outcomes from cardioversion increase dramatically in patients with conventional risk factors for thromboembolism.

Additional Resources Retrospective Study Journal Scan Management of Patients With AFib Compilation of 2006 ACCF/AHA/ESC and 2011 ACCF/AHA/HRS Recommendations  AFib CardioSource Clinical Community  ACC's Anticoagulation Initiative AFib Clinical Toolkit AnticoagEvaluator Mobile App  CardioSmart for Your Patients: Learn More About AFib

In the FinCV study, researchers followed clinical outcomes from 5,116 successful cardioversions in 2,481 patients treated for AFib lasting fewer than 48 hours before treatment. None of the patients received oral anticoagulation or periprocedural heparin therapy. The overall rate of stroke or other thromboembolic event in the 30 days following cardioversion was 0.7 percent even without perioperative coagulation. But the risk for thromboembolic events was significantly elevated in patients with traditional risk factors for stroke, including age over 60 (OR=1.05, p<0.01), female gender (OR=2.1, p=0.03), heart failure (OR=2.9, p=0.03) and diabetes (OR=2.3, p=0.03). Patients with both heart failure and diabetes were at 9.8 percent increased risk for thromboembolism. Recent guidelines call for oral anticoagulation in acute AFib patients with risk factors for stroke undergoing cardioversion.

The 2010 European Society of Cardiology guidelines for the management of AFib included the class I level B recommendation: "For patients with AFib <48 h and at high risk of stroke, intravenous heparin or weight-adjusted therapeutic dose low molecular weight heparin is recommended peri-cardioversion, followed by oral anticoagulant therapy with a vitamin K antagonist (international normalized ratio 2.0–3.0) long term¹." However, the "implementation of the guideline has been slow, since the evidence behind the recommendation is circumstantial and supported only by small retrospective cardioversion studies," said lead author Juhani Airaksinen, MD, PhD, Turku University Hospital, Turku, Finland. "Our present data strongly support the European recommendations."

While the study is based on retrospective data, a prospective randomized trial may be unethical, noted Nikolaos Dagres, MD, University of Athens, Athens, Greece, in an editorial comment about the study. The Finnish trial and similar high-quality retrospective studies represent the best data likely to become available.

"These results have important clinical implications," Dagres said. "They prove the correctness of current guidelines, which recommend anticoagulation therapy in patients with risk factors even if the [AFib] duration is presumed to be less than 48 hours. It is reassuring that patients without risk factors for stroke and with a brief duration of preceding [AFib] had a very low rate of thromboembolic events."

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Endnote

1. Camm AJ, Kirchhof P, Lip GY et al. Guidelines for the management of atrial fibrillation: the Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC). Eur Heart J 2010;31:2369-429.

Keywords: Vitamin K, Thromboembolism, Stroke, Heart Failure, Heparin, Atrial Fibrillation, Risk Factors, Diabetes Mellitus, United States

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