AEM: ED patients with flutter need defibrillation, not drugs
Researchers found that electrocardioversion, rather than anti-arrhythmic drugs, provided faster conversion to normal rhythm and shorter hospital stays, according to a study of the largest group of emergency department (ED) patients with atrial flutter evaluated to this point, which was published online Jan. 20 in Annals of Emergency Medicine.

"Management of atrial flutter patients in the emergency department is controversial," said lead study author Frank Scheuermeyer, MD, from the department of emergency medicine at St. Paul's Hospital and the University of British Columbia in Vancouver, B.C. "There is no standard formula for treatment of these patients by emergency physicians. For that reason, although atrial flutter is very common, management of it in the emergency department has created a therapeutic dilemma for emergency physicians."

The researchers retrospectively collected data from 122 consecutive patients with a primary ED diagnosis of atrial flutter from two urban hospitals between April 1, 2006, and Jan. 31, 2009.

Of the 46 patients who were treated with electrocardioversion, 91 percent achieved a normal heart rhythm, and 93 percent were discharged home. Of the 15 patients who were treated pharmacologically (oral or intravenously), 27 percent achieved a normal heart rhythm, and 60 percent were discharged home. No patients in either group died or experienced a stroke in the next year.

Both groups had similar age and stroke risk profiles. However, most of the patients in the electrocardioversion group had previous atrial fibrillation or flutter, and the majority had previously received successful cardioversion.

Despite similar age and risk profiles between the two groups, patients receiving anti-arrhythmic drugs had a far lower rate of conversion. In addition, their average length of stay in the ED was six hours, compared with three hours for the electrocardioversion group.

"The poor success rates and relatively high admission rates suggest that rhythm control with amiodarone [Cordarone, Wyeth/Pfizer], procainamide [Pronestyl, Bristol-Myers Squibb], and propafenone [Rythmol, GlaxoSmithKline] is not an ideal first-line therapy for atrial flutter in the ED," according to the study. Scheuermeyer et al noted that ibutilide was not available at their institutions.

Of the 11 patients who failed anti-arrhythmic therapy, six received subsequent electrical cardioversion attempts at the index visit, of which four were successful.

"High success and low complication rates in electrocardioversion group suggest that electrical cardioversion may be an appropriate ED strategy for low-risk patients with atrial flutter," researchers said.

However, they reported that those undergoing defibrillation required substantial amounts of energy, with 17 percent receiving at least 150 joules to achieve a normal heart rhythm. This contrasts with cardiology literature suggesting that 70 percent of patients convert to normal rhythm with much lower energy levels (20 to 30 joules). None went into atrial fibrillation, despite cardiology research that suggests that 10 to 15 percent of patients receiving defibrillation for atrial flutter may be shocked into fibrillation.

Emergency physicians used a number of methods to treat patients with atrial flutter. Patients who had been in flutter for more than 48 hours or whose onset times were unclear received rate control, whereas patients with arrhythmia durations of less than 48 hours received attempts at rhythm control.

A third group of 15 patients spontaneously regained normal sinus rhythm within three hours of ED arrival. They had a similar low-risk profile as the other two groups, but were slightly older (mean age 61 years). Two deaths occurred in this group, but were unrelated to their atrial flutter.

A fourth group of 24 patients in which rate control was attempted had a mean age 63 years and higher CHADS2 scores than the other groups. Most patients had been in atrial flutter for more than 48 hours or their status about the time of onset was unclear. Seventeen patients received metoprolol (Lopressor, Novartis), four diltiazem (Cardizem, Biovail) and three verapamil. The discharge rate was lowest in this group (58 percent) and of the 14 patients discharged, six began receiving rate control agents, and four others who were already receiving rate control agents had their doses increased. There were two deaths unrelated to the atrial flutter.

"Our study suggests that electrical cardioversion was preferred for eligible patients and was more successful than chemical intervention," said Scheuermeyer. "This suggests that cardioversion is faster and more effective, making it a dominant first-line strategy for eligible patients."

Researchers also noted that their data help to define the epidemiology of atrial flutter patients who present to EDs—"a group who may be substantially different from those described in cardiology and electrophysiology literature."

A significant strength of the study, they said, was that all diagnoses of atrial flutter were confirmed by ECG.