The RACE to Cardiovert: Should We Cardiovert Recent-Onset Atrial Fibrillation in the ED?

In adapting to AF, the heart undergoes structural, chemical, and electrical remodeling (25,26) that over time make cardioversion less successful and less sustainable (27,28,29). As such, it has been suggested that early cardioversion may allow for higher rates of sustained sinus rhythm before this pathological remodeling takes root (30,31,32).

Although the cohorts were small and likely imbalanced, a closer inspection of the data in Pluymaekers et al (1) demonstrated a large difference in the rate of successful pharmacologic cardioversion in early group (74.1%) vs delayed group (36.4%). Another study also showed decreased rates of successful pharmacologic cardioversion after an AF duration of 24 hours (33). Rate control prior to cardioversion in the delayed group may explain these findings, as prior rate control may be associated with decreased rates of successful cardioversion (34).

During the shared decision-making process, providers should inform patients of the potential reduced efficacy of pharmacologic conversion, and subsequent need for electrical cardioversion, if the delayed approach is selected.

Pluymaeker et al (1) rightly point out the importance of anticoagulation in AF. The absence of adequate atrial contraction predisposes to thrombus formation. Once thrombus has formed, conversion back to sinus rhythm can disrupt the thrombus and propel an embolus out of the heart and into the systemic circulation. Studies have shown that the risk of thromboembolic events increases with duration of dysrhythmia (16). For patients less than 60 years of age without heart failure, the rate of thromboembolic event is just 0.2% (15). Conversely, in patients with diabetes and heart failure, the risk of cardioversion-related thromboembolic events is 9.8% (15).

In the Pluymaeker study, all patients were offered anticoagulation in accordance with their CHA2DS2-VASc score, regardless of successful conversion to normal sinus rhythm. This is in accordance with 2014 guidelines by the American College of Cardiology and American Heart Association (23). As per this task force, the decision to anticoagulate “should be individualized based on shared decision-making after discussion of the absolute and relative risks of stroke and bleeding and the patient’s values and preferences”. They further specify that those patients identified as “low thromboembolic risk” with AF for less than 48 hours may be cardioverted “without the need for post-cardioversion oral anticoagulation.” Tampieri et al (35) demonstrated the safety of this practice, with no episodes of TIA, stroke, or death within 30 days following cardioversion for AF less than 48 and CHA2DS2-VASc score of 0-1 for males or 0-2 for females.

In contrast, for those patients with AF for longer than 48 hours in whom cardioversion is planned, current guidelines (23) recommend anticoagulation for 3 weeks before and 4 weeks following cardioversion, regardless of CHA2DS2-VASc score. It therefore follows that cardioversion of low-risk patients within 48 hours may avoid the need for short term anticoagulation and its associated risks.

A survey of Kings County/SUNY Downstate faculty to assess departmental practice variation in the management of stable, recent-onset AF yielded 23 responses. The majority (78%) indicated that they rarely to never cardiovert, with the remaining 22% indicating “usually” or “always.” The most common reasons for not cardioverting was uncertainty over time of onset (50%). Other respondents noted: resistance from patients, lack of buy-in from ED administration or cardiology, fear of thromboembolism, lack of evidence supporting ED cardioversion, medicolegal fears, and high spontaneous rate of cardioversion. Respondents were split in initial method of cardioversion: 58% preferring pharmacological, 42% preferring electrical. Respondents were more unified with 89.5% responding that they have rarely or never seen a complication related to cardioversion, with only 9.5% indicating “sometimes.”

1. “Uncertainty over time of onset”

It is a valid fear that patients may experience AF without manifesting recognizable symptoms (36). However, this is largely irrelevant given the multitude of studies demonstrating the safety of cardioversion for recent-onset AF based on patient-reported symptoms (4,5,6,15,16,17).

2. “Afraid to throw a clot”

Putting aside the fear of uncertainty over time of AF onset, providers may still avoid cardioversion over a theoretical risk of iatrogenic thromboembolism. However, from a pathophysiologic standpoint, this argument is invalid. Thromboembolism may occur when a clot, formed while a patient is in AF, is propulsed into systemic circulation after return of atrial contraction upon cardioversion. This process is the same if a patient spontaneously converts or is pharmacologically or electrically cardioverted. Thus, discharging a patient on rate control alone does not prevent the patient from “throwing a clot”, as up to 70% of these patients spontaneously cardiovert to sinus rhythm on their own (1,7). 

Furthermore, as previously discussed, the longer the duration of dysrhythmia the higher the risk of thromboembolism. Therefore, if the provider is concerned about avoiding a thromboembolic event, it would be intuitive to cardiovert as close to the onset of symptoms as possible.

3. “Lack of buy-in from cardiology and/or administration”

Emergency physicians do not practice in a bubble, and we should work with our colleagues from other departments. As such, when considering a change in practice, we should invite other clinicians who may be involved in the patient’s follow-up care. An example is described in Baugh et al (20). Emergency physicians, general cardiologists, electrophysiologists, nurses, pharmacists, and hospital administrators formed an expert panel to devise an algorithm to reduce the number of admissions and identify those patients who can safely be discharged or assigned to observation.

4. “I don’t want to get sued”

Malpractice is a common fear among physicians across all specialties, and emergency physicians are not exempt (37). However, Schoenfeld et al (38) demonstrated that shared decision-making can help lower the risk of being involved in such a suit. Therefore, discussing the risks, benefits, and alternatives of cardioversion may be the best strategy, rather than simply admitting a patient or deferring to another service.

Atrial fibrillation affects 1-2% of the US population, (39,40) and accounts for approximately 0.5% of ED visits (18). This number should increase with the aging of the population.

For many patients, AF will produce discomfort; yet once rate-controlled, AF certainly can be managed safely as an outpatient. Receiving the diagnosis of AF surely does not conjure the same emotions of a diagnosis of cancer. This is in spite of the fact that the discharge diagnosis of AF portends a dire life course: within 1 year, 5-10% will die and 10-20% will suffer stroke, embolism, myocardial infarction, or acute heart failure (41).

As emergency physicians, our doors are constantly flooded with patients with chronic conditions, many of such can be safely managed in an outpatient setting without expert resuscitation. For so many of these conditions (diabetes, congestive heart failure, cancer, hypertension, etc) there is little we can do to significantly alter its course. In recent-onset AF, we can maybe play a role in altering its course and reduce the risk of persistent AF and its downstream consequences, so perhaps we should strive to do so.

Furthermore, when we first put on the white coat in medical school, we did not go into medicine just to order tests and to practice defensive medicine. We went into medicine to be healers, hoping to alleviate the pain and distress of patients and to promote happy and healthy lives. If we emergency physicians have a way to safely alleviate the symptoms of AF through cardioversion, we should have a discussion with patients and offer them the option.