ED Cardioversion for New Onset A-Fib
Search Strategy: Using PUBMED you combine individual searches for “atrial fibrillation”, “cardioversion”, and “emergency department” to yield 122 citations including the four manuscripts selected below (see http://tinyurl.com/7ele899).
It is your first shift back after an intriguing series of lectures at the annual Society for Academic Emergency Medicine (SAEM) meeting where you learned that some (low-risk) pulmonary embolism patients are being discharged home directly from the ED with anticoagulation, as are some new onset atrial fibrillation patients. Of course, your first patient this shift is a 35-year-old female with palpitations beginning two-hours ago. The EKG demonstrates atrial fibrillation which was not present on the only other EKG that you can find which was from 5-years ago. She has no significant past medical history, denies alcohol or illicit substance abuse, and appears well with a blood pressure of 100/50 and irregular heart rate of 135.
Hmmm. Do you become an early adopter and recommend immediate ED cardioversion followed by discharge home? Or do you reflexively admit this patient to “work-up” her new onset atrial fibrillation justifying your deviation from the new evidence presented at SAEM by telling the patient that she needs to be monitored for worsening atrial fibrillation or hypotension while awaiting an inpatient echocardiogram and serial cardiac enzymes? How comfortable are you with the data and do you want to be “the early adopter”?
Population: Otherwise healthy new onset atrial fibrillation patients in the ED
Intervention: ED electrical or chemical cardioversion and discharge home
Comparison: Standard of care (telemetry, serial enzymes, admission)
Outcome: Hypotension, dysrhythmia, cardiac mortality, length of stay, cost
Second years: Association of the Ottawa Aggressive Protocol with rapid discharge of emergency department patients with recent-onset atrial fibrillation or flutter, CJEM 2010; 12: 181-191. (http://pmid.us/20522282)
ED crowding is an increasingly prevalent threat to patient safety that is exacerbated by prolonged ED lengths of stay and lack of hospital bed availability (see also Moskop 2009 and Moskop 2009). Atrial fibrillation is currently one of the most common dysrhythmias managed in the ED. Since the incidence of atrial fibrillation increases with age (incidence = 1% ages 60-68, 5% in persons older than 69 years, and 8-10% of those over age 80 years), hospital admissions for atrial fibrillation have increased 66% over the last 20 years and will increase rapidly with aging baby-boomers if current conservative management strategies continue. Inpatient costs for non-valvular atrial fibrillation were $1.95 billion in 2005.
The standard of care “conservative” atrial fibrillation management strategy has been rate control, anticoagulation, and admission. The overriding motivation for this strategy is to prevent strokes, since 15% of all strokes are directly attributable to atrial fibrillation. The Framingham data also suggests a 1.5-1.9 fold increased risk of death associated with chronic atrial fibrillation, largely due to thromboembolic strokes. Atrial fibrillation is increasingly refractory to conversion to normal sinus rhythm the longer it persists and structural heart damage increases with longer duration of atrial fibrillation. Nonetheless, several trials have now demonstrated that in chronic atrial fibrillation rhythm control offers no advantages to rate control, at least in geriatric adults (AFFIRM, AF_CHF). However, new onset atrial fibrillation is not synonymous with chronic atrial fibrillation and research like the AFFIRM trial do not directly apply to the ED management of recent-onset episodes of symptomatic fibrillation.
Increasingly, research supports pharmacological or electrical cardioversion of new-onset atrial fibrillation patients in the ED (Michael 1999, Domanovits 2000, Burton 2004, Alboni 2004, Zahir 2005, Dankner 2009, Scheuermeyer 2010, von Besser 2011, Cristoni 2011). Alternatively, some are advocating a “wait and see” approach whereby stable new onset atrial fibrillation patients are neither cardioverted nor admitted (Doyle 2011). Unfortunately, ACEP currently has not published guidelines/clinical policies for the ED management of acute atrial fibrillation. The American College of Cardiology, American Heart Association, and Heart Rhythm Society atrial fibrillation guidelines have no emergency medicine representation amongst their authors and consequently do not provide any recommendations for the ED management of acute, stable atrial fibrillation. Future atrial fibrillation guidelines need to incorporate the ED management of acute onset A-fib into therapeutic recommendations.
What do the available studies teach us about the effectiveness and safety of ED-based rapid atrial fibrillation cardioversion? The studies are all single-center (likely underpowered) non-randomized (exception is the PGY IV paper) designs indicating that ED cardioversion of acute onset atrial fibrillation in physician-selected patients is often immediately effective at restoring normal sinus rhythm while reducing hospital length of stay and costs without significantly increasing adverse effects. It is important to note that the average age of patients in these studies was 63 years old, although our consensus was that a rapid cardioversion protocol would be most appropriate in young adults not geriatric adults. Nonetheless, the research data we analyzed had no age restrictions and represented a substantial portion of older adults, even octogenarians. Note that most of these studies were under-powered. Some experts consider studies that lack a priori or post-hoc power calculation to be unethical.
The Kaiser-Permanente data provided evidence that community-hospital based rapid cardioversion and discharge home for A-fib or A-flutter is safe and effective, avoiding 89% of admissions with a 30-day stroke risk of 1% (95% CI 0.1-3.5%) and no identified cases of mesenteric ischemia or peripheral limb ischemia. The Mayo group demonstrated that an 8-hour ED observational unit protocol based upon pharmacological rate control with electrical cardioversion after 6 hours if A-fib persisted reduced admissions from 100% to 12% while reducing length of stay by 11 to 20 hours without increasing readmissions, stroke or death rates. However, future pragmatic community-based trials in less structured, less integrated healthcare networks still need to assess the most effective cardioversion management algorithm, clinician acceptance/adherence, and cost-effectiveness.
Although our group questioned the veracity of follow-up in the study we reviewed, most agreed that the Ottawa protocol is the most compelling. It is an ED-based rapid chemical-then-electrical cardioversion protocol for adults with A-fib/A-flutter symptoms of less than 48 hours duration (or in those with a therapeutic INR for at least 3-weeks). The Ottawa protocol significantly reduces admission rates and ED length of stay: 96.8% of patients discharged home after a median 5-hour ED stay, including 90% in normal sinus rhythm. Here is the protocol:
Step I: Assessment
- Stable BP, no ACS or CHF
- Onset < 48º
- Symptom severity
- Previous episodes/treatment
- Therapeutic INR
Step II: Rate Control
- Only if severe symptoms or no cardioversion
- Diltiazem 0.25 mg/kg IV over 10 minutes or Metoprolol 5 mg IV Q15 minutes
Step III: Pharmacologic Cardioversion
- Procainamide 100 mg IV over 60 minutes
- Hold if SBP < 100
Step IV: Electrical Cardioversion
- NPO for 6-hours
- Propofol/fentanyl procedural sedation
- 150-200 J biphasic synchronized to start
Step V: Anticoagulation
- None if symptoms <48 hours or INR therapeutic >3wks
- Consider initiating if CHADS2 > 1
Step VI: Disposition
- Home within 1 hour of cardioversion
- Outpatient Echo if first episode
- Cardiology follow-up
- If not cardioverted discharge with rate control meds and Coumadin and elective cardioversion with Cardiology within 4 weeks
Future research of the Ottawa protocol needs to delineate whether:
- The effectiveness and safety of the protocol is replicable;
- Patients and physicians readily accept this paradigm shift in atrial fibrillation management;
- There are optimal anti-arrhythmic agents/doses, electrical cardioversion techniques (energy level, paddle position) and procedural sedation strategies;
- A rapid cardioversion protocol is cost-effective.
In the meantime, guideline developers must begin to contemplate ED-based management of acute-onset A-fib/A-flutter that they have neglected in the past. A systematic review of all current rapid cardioversion protocols using the MOOSE guidelines would be a useful addition to the medical literature.