Data Support Aggressive A-Fib Protocol
NEW ORLEANS — Treatment of acute-onset atrial fibrillation or flutter using the Ottawa Aggressive Protocol for rapid emergency department rhythm control yielded a 91% conversion rate in a large consecutive patient series.
“To extrapolate, widespread use of the Ottawa Protocol could lead to a significant decrease in hospital admissions for acute atrial fibrillation or atrial flutter where that's the local practice, and otherwise to rapid disposition of patients who can quickly resume normal activities of daily life,” Dr. Ian G. Stiell said at the annual meeting of the Society for Academic Emergency Medicine.
He presented a retrospective study of 385 consecutive patients who were managed in two Ontario EDs according to the Ottawa Aggressive Protocol (OAP). Fully 91.4% were discharged home in sinus rhythm after a median ED stay of 5.6 hours, with instructions to see a cardiologist within the next month.
During the next 30 days, 30% of patients had a recurrence of their atrial arrhythmia. Half were successfully cardioverted. A total of 16% of patients were admitted to the hospital. No cerebrovascular accidents or cardioversion-related adverse events occurred, according to Dr. Stiell of the University of Ottawa.
The OAP for ED management of acute atrial fibrillation or flutter was developed several years ago in response to a prevailing lack of consensus on the optimal way to manage these common arrhythmias in the ED.
The OAP entails an initial attempt at pharmacologic conversion using intravenous procainamide infused at 1 g over 1 hour. If the patient has a history of previous lack of efficacy for intravenous procainamide, an alternative intravenous antiarrhythmic agent may be used before moving on to electrical cardioversion in the ED. Patients with a history of multiple unsuccessful prior attempts at pharmacologic cardioversion using all available intravenous rhythm-control drugs proceed straight to electrical cardioversion.
Pharmacologic conversion was attempted in 65% of patients in this series, with a success rate of 42% in patients with acute atrial fibrillation and 27% for those with atrial flutter. Procainamide had a 43% success rate in converting patients to sinus rhythm, vernakalant had a 70% success rate, and amiodarone had a 9.5% success rate. Vernakalant's marketing application is now under review by the Food and Drug Administration.
Electrical cardioversion was attempted in 68% of patients, with a 90.3% success rate. Typically, one emergency physician oversaw the electrical cardioversion while another or a senior resident managed the sedation, consisting of a small dose of fentanyl followed by bolus propofol.
“We usually start at a pretty high energy level of 150 J biphasic. Our cardiologists tend to favor starting high and just doing it once,” Dr. Stiell explained.
Under the OAP, patients are not anticoagulated prior to attempted electrical cardioversion. “Our standard is to focus on the time of onset. If it's clearly less than 48 hours, then we're comfortable in cardioverting without giving heparin, aspirin, or warfarin,” Dr. Stiell said. “If the patients are converted, they'll typically go home without warfarin. They'd be encouraged to have follow-up with cardiology.”
On the other hand, if the time since arrhythmia onset is unclear or is greater than 48 hours, emergency physicians won't proceed with electrical cardioversion unless they have access to a reassuring transesophageal echocardiogram.
In this series, mean duration of symptoms prior to presenting to the ED was just 4 hours, he added.
Some investigators assert that having a rate-control drug on board enhances the success rate of attempted electrical cardioversion. That wasn't the case in this study, according to Dr. Stiell: 47% of patients received intravenous rate-control drugs prior to attempting cardioversion, but they proved to have no effect on the direct-current cardioversion success rate.
'Use of the Ottawa Protocol could lead to a significant decrease in hospital admissions.'
Source DR. STIELL
