The presenting symptoms for AF and HF are relatively similar and nonspecific. Typical symptoms of AF include chest pain, light-headedness, fatigue, palpitations, nausea, and dyspnea [16]. The most common symptoms and signs of HF include dyspnea, peripheral edema, cough, orthopnea, chest pain, weakness, nausea/vomiting, and fatigue [17]. The characteristic electrocardiogram (ECG) findings of AF, along with an irregular pulse, are likely to be recognized early on in patients presenting with AF and HF. Once AF is recognized and assuming the patient is not unstable, there are several useful pieces of historical information to obtain. First, it is helpful to ascertain the history of the patient’s current symptoms with a focus on whether or not the AF is a long-standing condition or new in the onset (e.g., <48 h), and whether or not the onset can be accurately identified. In patients with prior episodes of AF, a quick investigation of past ED treatment approaches may also be useful. If HF is suspected clinically, then it is important to gather information regarding prior episodes, potential precipitating factors such as diet, medication omissions/errors, and echocardiogram results (e.g., does the patient have primarily systolic or diastolic dysfunction). Lastly, other comorbidities and current medications the patient is taking, including anticoagulant, antiplatelet, and other cardiovascular (e.g., beta-blockers, digoxin, calcium channel blockers) medications, will help inform subsequent decision-making.

With or without concomitant HF, AF presentations have been categorized in numerous ways such as asymptomatic, paroxysmal, persistent, permanent, perioperative, lone, and recurrent (Table 20.3) [14]. All of these categories refer to the timing of onset and/or duration of AF. For patients not requiring urgent cardioversion due to instability, the duration of AF is the most important factor in determining whether chemical or electrical cardioversion can be safely attempted in the ED.

For any patient with AF and HF, acquiring vital signs on presentation, setting up critical care monitoring, obtaining IV access, and performing a rapid exam are central to the initial assessment. The focus for patients with AF and HF needs to first be directed at determining if there are signs of instability such as hypotension, respiratory failure, ischemic chest pain, severe HF, or altered mental status. If these, or other signs of instability, are present and the patient is experiencing a rapid heart rate due to AF, then urgent synchronized cardioversion based on advanced cardiac life support [18] (see below) is indicated. At the same time, if HF is felt to be playing a significant role in the patient’s presentation, then respiratory and pharmacologic therapies directed at the HF should be started. If the patient is stable, a thorough exam focusing on mental acuity, neurologic status, heart and lung auscultation, the abdomen, peripheral perfusion, and edema should be undertaken. Paying particular attention to the heart exam may uncover significant valvular disease, which may be contributing to the present symptoms.

For many patients who meet the clinical criteria for AF and HF, more than one underlying disorder may be contributing to the patients presenting symptoms. Thorough appreciation of all the underlying causes for the patient’s signs and symptoms requires a careful diagnostic workup to achieve the best possible outcomes. In general, the diagnostic testing in patients with AF and HF does not differ significantly from that of patients with HF alone. All patients should receive an electrocardiogram (ECG), cardiopulmonary monitoring, and a chest X-ray on arrival. On the ECG, you would look for the abnormalities such as the characteristic findings of AF, evidence of ischemia, and signs of preexcitation. Laboratory tests may vary with suspicion of certain etiologies for AF and HF but often will include basic hematology tests, serum markers of myocardial injury, a natriuretic peptide, electrolytes, and kidney function. Thyroid function tests, which may often be considered, have been found to be abnormal in many patients with AF but are only rarely (<1 % in a large registry [16]) felt to be the cause of the AF itself. In patients where there are concerns based on history, exam, or ECG for ongoing myocardial ischemia, valvular disease, or pericardial effusion, it may be useful to obtain an urgent echocardiogram in the ED.

The hemodynamically unstable patient with AF and HF needs urgent cardioversion if the instability is felt to be due to AF-mediated tachycardia. Significant acute HF may be a sign of instability in the AF patient regardless of whether the AF caused the HF or vice versa. In either case, converting the AF to sinus rhythm, even transiently, may normalize vital signs and facilitate treatment of the HF.

The preparation for emergent cardioversion includes administering analgesics and sedatives when possible. However, if the patient is suffering a severe decompensation, this step may have to be omitted. In addition for patients whose AF has lasted ≥48 h, intravenous heparin should be administered at the time of cardioversion and continued after the procedure as a bridge to 4 weeks of total anticoagulation [14]. The placement of the defibrillator pads is somewhat controversial but the anterior–posterior position is likely to be the most efficacious in the majority of AF patients [19]. The amount of energy required to convert the patient to sinus rhythm from AF is generally higher than that for atrial flutter [14] and also varies depending on whether the defibrillator is monophasic or biphasic. For monophasic, 200 J is a reasonable starting point, whereas for biphasic, 100 J is likely to be effective [14, 20, 21]. For patients with implanted pacemakers, cardioversion can proceed as usual, but care should be taken to avoid placing the defibrillator pad over the generator [14]. Although therapy with antiarrhythmic agents prior to cardioversion has been shown to increase efficacy of elective cardioversion [22], in the unstable patient, this is generally not an option.

In the setting of concomitant decompensated HF, the rate of recurrence of AF after successful cardioversion is likely to be high [23], so therapies aimed at improving HF should be started immediately once the patient is more stable. The use of antiarrhythmic agents, such as amiodarone, after cardioversion may help to prevent early recurrence, but in the acute setting, the decision to use these agents should be made on a patient-by-patient basis [14] in conjunction with a consultant.

After cardioversion, in addition to treating underlying HF, it is important to obtain another ECG to evaluate for the presence of an acute coronary syndrome (ACS). Furthermore, this reevaluation should maintain a broad differential diagnosis so as not to miss other contributing conditions such as adverse medication reactions, alcohol or drug toxicity (e.g., digoxin), electrolyte disturbances, valvular heart disease, pulmonary emboli, and sepsis/septic shock.

Although HF in the setting of AF can be considered a sign of instability, many cases will be of milder severity and not require urgent cardioversion. These patients may fall into various categories such as rapid AF with mild HF, HF with only a history of AF, or HF and AF without tachycardia. In cases where urgent cardioversion is not needed, strategies to control rate, initiate anticoagulation if indicated, potentially convert the rhythm (electrical or chemical), and treat the underlying HF, will all need to be considered and instituted where appropriate.