NEW YORK (Reuters Health) – In keeping with recommendations, anticoagulation appears beneficial after cardioversion of acute atrial fibrillation (AF), according to Finnish investigators.
In fact, the study showed that the risk of stroke is six times higher after cardioversion of acute AF than after six months of chronic AF with no anticoagulation, Dr. K. E. Juhani Airaksinen told Reuters Health by email.
Recent guidelines do call for anticoagulation during and after cardioversion in patients with acute atrial fibrillation and risk factors for stroke. But that advice is mainly based on consensus, Dr. Airaksinen of Turku University Hospital and colleagues said in their report of the new study.
To gather more evidence, the researchers looked at registry data on cardioversions in patients with atrial fibrillation lasting less than 48 hours.
In all, there were 5,116 successful cardioversions in 2,481 patients, none of whom received periprocedural heparin or oral anticoagulants.
Within 30 days, there were 38 definite thromboembolic events, including 31 strokes. Four other patients had transient ischemic attacks at a mean of two days after cardioversion.
In general, the investigators say, these events were quite rare (with a risk of less than 1%) and within the same range as in unselected patients undergoing elective or acute cardioversion during therapeutic anticoagulation.
But older age, female gender, heart failure and diabetes increased the risk, and in the presence of multiple risk factors the risk became unacceptably and significantly higher (by about 10%) than with pre- and post-cardioversion anticoagulation.
“Our results,” say the investigators, “support the current recommendation that these patients need effective periprocedural anticoagulation followed by long-term oral anticoagulation.”
Dr. Airaksinen added, “The embolic complications occur typically two to three days after cardioversion, and the clinician responsible for cardioversion may not be aware of the harm done. Adequate periprocedural anticoagulation is important in the prevention of these devastating complications.”
In an editorial, Dr. Gerhard Hindricks notes that because guidelines recommend anticoagulation in these patients, “a randomized trial would be unethical. Thus, retrospective data of good quality is probably the best we can rely on.”
Given these and other limitations, Dr. Hindricks of the University of Leipzig concludes that the study “convincingly demonstrates the necessity of effective anticoagulation in patients with risk factors for stroke even if the duration of AF preceding cardioversion is assumed to be less than 48 hours.”
The paper is to appear in an upcoming issue of the Journal of the American College of Cardiology.
J Am Coll Cardiol 2013.