Atrial Fibrillation Management in Emergency Departments: A New Protocol Assessment

Non-valvular atrial fibrillation (AF) is the most frequently encountered heart rhythm disorder in emergency medicine. It is at the origin of one third of hospitalizations for arrhythmia [1, 2]. Its prevalence is about 1.5 to 2% of the general population and increases quickly with age, reaching over 10% in 80-year-old subjects and over 20% after 90 years of age [3]. Death rates are doubled by AF, due to an increased risk of thromboembolic [4-7] and hemodynamic complications [1-3] and an increased risk of hospitalization [1]. Because emergency physicians are often the first to manage these patients, we easily understand the challenge of optimal management of early discovered atrial fibrillation in emergency departments (ED).


Introduction
Non-valvular atrial fibrillation (AF) is the most frequently encountered heart rhythm disorder in emergency medicine. It is at the origin of one third of hospitalizations for arrhythmia [1,2]. Its prevalence is about 1.5 to 2% of the general population and increases quickly with age, reaching over 10% in 80-year-old subjects and over 20% after 90 years of age [3]. Death rates are doubled by AF, due to an increased risk of thromboembolic [4][5][6][7] and hemodynamic complications [1][2][3] and an increased risk of hospitalization [1]. Because emergency physicians are often the first to manage these patients, we easily understand the challenge of optimal management of early discovered atrial fibrillation in emergency departments (ED).
Recommendations for AF management were issued by the European Society of Cardiology (ESC) in 2010 [1], with an update in 2012 [2]. AF diagnosis is based on electrocardiogram (ECG), but treatments depend largely on clinical context and co-morbidity conditions. ESC recommendations also emphasize thromboembolic risk stratification, which is the most frequent complication [8], using the CHADs -VASc score [2], and underline the importance of rhythm control strategy (anti-arrhythmic drugs) and/or heart rate control (beta-blockers). Strict application of the recommendations is difficult for emergency physicians to apply. Some drugs are not suitable in ED because of their dosages and the need for prolonged surveillance and in addition, emergency physicians are called upon to decide between rhythm or heart rate control strategy. This lack of clarity may present a handicap in ED. An algorithm for management of newly discovered or poorly controlled AF in the ED has been developed in collaboration with cardiologists, at our University Hospital. While respecting ESC guidelines [1,2], the algorithm implements heart rate control strategy, supervises anti-thrombotic therapy as well as application of specialized re-views and proposes a discharge strategy. We aimed to prospectively evaluate this protocol.

Patient selection
Patients with AF newly discovered in the ED, or those with AF previously diagnosed but with inappropriate ventricular rate (>110bpm) causing symptoms or hemodynamic distress in ED, were eligible for inclusion by the managing emergency physician. Exclusion criteria included the following: age younger than 18 years, AF manifested initially as an ischemic stroke or transient ischemic attack, previously diagnosed and treated AF without symptoms in ED, other supra-ventricular rhythm disorders other than AF. Clinical history (persistence of symptoms, previous cardiovascular disease, risk factors of AF, medication reported by the patients), physical evaluation, 12-lead ECG, standard blood tests, chest radiography and stroke risk estimation were performed on all included patients. All data were collected prospectively and directly reported in a case report form by the treating physician.

Outcome measure
The primary outcome was the proportion of patients with a sinus rhythm or heart rate below 100 bpm without persistent symptoms (chest pain, dizziness, dyspnea, fatigue, palpitations) at discharge from ED. Emergency physicians and cardiologists set up a protocol for initial management of acute AF in ED (Figure 1), that was based on the guidelines for the management of AF published in 2010 and updated in 2012 [1,2]. The algorithm required stroke risk estimation, search for AF complications and conditions that predispose to AF. Control of the ventricular rate, anti-thrombotic therapy, cardiologist consultation and ED discharge were decided according to the algorithm. The protocol was approved by the rhythmologists of our institution.

Data analysis
Data were recorded using Excel® software (Microsoft Corporation, Richmond, USA). Statistical analyses were performed using STATA11 software (StataCorp LP, College Station, TX). Comparative analyses were performed using the x²-test and Fisher's test for percentage comparisons. Student test and Mann-Whitney test were performed for comparisons of averages and medians. A p value less than 0.05 was considered statistically significant for all tests.

Results
Demographic data (Table 1) During the study period, 58 patients fulfilled the inclusion criteria and were treated in accordance with the proto-col. Mean age was 76 years. AF was the main reason for admission to ED for 26 (45%) of them. Fifty-two per cent (n=30) were women. AF was first diagnosed in ED in 39 (67%) patients. Most patients were hemodynamically stable (n=54, 93%).

Journal of Anesthesia & Intensive Care Medicine
All in all, 74% of the patients (n=43) were successfully treated: 9 patients (15%) had recovered sinus rhythm and 34 patients (59%) remained arrhythmic but with a heart rate lower than 100bpm and no persisting symptom on discharge from the ED (p≤0.05). Among the 26% of the patients (n=15) whose heart rate was higher than 100bpm at the end of treatment, none presented with poorly tolerated AF (hemodynamic or respiratory disorders). Analysis of the sub-groups showed good results for 96% (n=26) of the least seriously ill patients (p <0.001) for whom no cardiologic advice was necessary, and for 87% of the patients (n=20) with past history of heart disease (p≤0.05). Whatever the result of treatment, hospitalization was the outcome for the majority of patients (62%; n=36), because AF was not necessarily the primary reason for admission in ED. All in all, treatment according to the protocol was a success for the majority of patients (91%; n=20) who returned home as well as the majority (64%; n=23) who were hospitalized (p≤0.05).

Discussion
We wished to validate a protocol adapted to ED to treat AF discovered at admission or poorly controlled. We showed that the use of the protocol was correlated to a treatment success rate of 74%. After four hours of hospitalization in an emergency department: 15% of the patients had recovered sinus rhythm and 59% showed a heart rate lower than 100bpm, without residual symptoms.

Characteristics of the population
The characteristics of the patients included were similar to those found in most of the studies of patients with AF in emergency departments [9][10][11]. In our study, sinus rhythm restoration came to 15%, a rate nonetheless lower than that found in patients treated with antiarrhythmics [12]. Achievement of a heart rate inferior to 110 bpm is considered in the literature as a reasonable objective. It is associated with a diminution in morbidity and in rate of hospitalization [13,14].

Therapeutic strategy
The protocol was designed to cover thromboembolic risk as well as risk of heart failure symptoms. Organization of requests for cardiologic advice facilitates selection of patients at risk, whose condition could necessitate specialized treatment. Patients with contraindications to the proposed treatment or whose condition necessitated the introduction of anti-arrhythmic treatment were likewise offered systematic cardiologic advice. The therapeutic measures recommended in our protocol were in agreement with the 2010 and 2012 recommendations of the l'ESC [1,2] and with the data of the literature.

Rate control
We opted for a strategy designed to control the heart rate with beta blockers; this strategy is recommended for aged patients with few symptoms (class 1A recommendation, ESC). In an emergency department it is difficult to precisely date AF onset and initiation of anti -arrhythmic treatment is consequently by no means devoid of risks. Moreover, no study has conclusively shown a difference in terms of mortality between strategies based on control of rate as opposed to those based on control of rhythm [15][16][17][18][19]. Nevertheless, anti-arrhythmic treatment could be applied in the event of poor hemodynamic tolerance (class 1B) or in patients having remained symptomatic following treatment in an emergency department (class 1B). A study by Atzema et al. [20] showed heightened risk of adverse effects and rehospitalization in the event of poor management of the beta blocker treatment. For Vinson et al. [21] introduction of a pharmacological treatment led in the majority of cases to sinus rhythm restoration. These data highlight the importance of satisfactory heart rate management in emergency departments.

Anticoagulation
Another study conducted by Atzema et al. [11] reported a constant increase over the last 10 years of the number of patients admitted to emergency departments with a CHA2DS2-VASc score greater than or equal to 2. According to Scheuermeyer et al. [22] half of the patients admitted to emergency for an AF problem left their wards without suitable anticoagulants. Our protocol, on the contrary, allowed for optimized anticoagulant treatment of patients admitted on account of AF. All of the patients treated were attributed a preliminarily calculated CHA2DS2-VASc score, in accordance with ESC recommendations. In fact, anticoagulant treatment is the treatment of choice for patients with a score greater than or equal to 2 (class 1A). As concerns patients with a score of 1, we opted for an anticoagulant (class 1A) rather than an antiplatelet treatment (class 1B). On the other hand, when treating women of less than 65 years of age and without any risk factor other than sex, we opted against use of anticoagulants (class 1B). In our protocol, we refrain from reference to the new anticoagulants (NOACs) for three reasons: their use is not associated with a higher level of evidence than classical anticoagulants (class 1A); they are recommended in the event of difficulties in use or adverse effects of the VKA drugs and INR instability (class 1B); they are reserved for non-valvular atrial fibrillations subsequent to cardiologic evaluation.

Limits of the study
Our study had biases, the first of which involved patient recruitment. Indeed, the protocol was not applied with regard to all the patients admitted to emergency with AF. Our study also showed a lack of power, which was due to the low number of patients having taken advantage of the protocol during the data collection period.

Conclusion
A protocol for treatment of recently discovered atrial fibrillation, based on the 2010 and 2012 recommendations of the ESC and taking into account the constraints related to the exercise of emergency medicine, brought about satisfactory results for 74% of the patients involved, over a time lapse not exceeding 4 hours. This protocol facilitates organization of requests for cardiologic