INTRODUCTION — The most common scenarios in which a diagnosis of new onset (and/or first-detected) atrial fibrillation (AF) is made include: a patient with new symptoms attributable to AF (see 'Presentation' below), an asymptomatic patient with an irregularly irregular and often rapid pulse (with a an electrocardiogram consistent with AF), or with an electrocardiographic rhythm recording device such as an external or implantable monitor or during pacemaker interrogation.
In those with a new diagnosis, AF can be paroxysmal (defined as stopping spontaneously within seven days) or be persistent (longer than seven days of continuous AF). (See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation", section on 'Classification and terminology'.)
This topic presents a broad overview to the approach to patients with newly diagnosed AF. Other related AF topics include:
●(See "Epidemiology, risk factors, and prevention of atrial fibrillation".)
●(See "Paroxysmal atrial fibrillation".)
●(See "Atrial fibrillation in adults: Use of oral anticoagulants".)
●(See "Rhythm control versus rate control in atrial fibrillation".)
●(Related Pathway(s): Atrial fibrillation: Anticoagulation for adults with atrial fibrillation.)
PRESENTATION — The findings of the history, physical examination, and electrocardiogram, as well as the initial evaluation of patients with AF are presented separately. (See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation".)
A new diagnosis of AF may result from one of the following clinical scenarios:
●At the time of a routine examination, during which the patient complains of symptoms possibly due to AF or is being evaluated for another reason and is found to have an irregularly irregular pulse.
●On an electrocardiogram obtained for other reasons such as a preoperative evaluation.
●A patient with a cerebrovascular accident or arterial thromboembolism is found to have AF that has not been previously diagnosed [1]. In some cases, this is picked up during extended monitoring in an attempt to diagnose the cause for the stroke.
●During electrocardiographic monitoring with a 24-hour ambulatory monitor obtained for some other reason or during interrogation of an implanted cardiac rhythm device.
●During hospitalization for another reason such as cardiac and noncardiac surgery, infection, recent myocardial infarction, thyrotoxicosis, pulmonary embolism, myocarditis, and pericarditis, among others [2-5].
●During recording from a patient-acquired recording device.
PATIENTS REQUIRING URGENT MANAGEMENT — Patients with newly diagnosed AF can often be managed in an outpatient setting. However, some patients require direct hospital admission or transfer to emergency department from an outpatient setting. Indications for transfer to a facility with emergency services include hemodynamic instability (usually manifested as hypotension), symptoms or signs of myocardial ischemia/infarction or heart failure, or evidence of pre-excitation (Wolff-Parkinson-White syndrome) on the electrocardiogram. Extreme, uncontrolled tachycardia independent of these findings may also be sufficient reason to admit. In addition, some patients with bothersome symptoms may require urgent rate control. (See 'Rate control' below.)
For some patients, the unstable condition may improve quickly after urgent rate control. For others, sinus rhythm needs to be restored immediately. Clinical judgment is needed to determine whether rate control should be attempted or whether to proceed directly to cardioversion, but the need for and type of anticoagulation before cardioversion must be considered first (see 'Rate control' below). Circumstances for which urgent or emergent cardioversion may be needed include (see "Atrial fibrillation: Cardioversion", section on 'Electrical cardioversion'):
●Active ischemia (symptomatic [eg, angina] with electrocardiographic evidence).
●Evidence of organ hypoperfusion or shock (eg, cold clammy skin, confusion, acute kidney injury).
●Manifestations of severe heart failure. (See "The management of atrial fibrillation in patients with heart failure".)
●Hypotension for which AF is suspected to be causal or contributory and for which standard therapy to treat underlying causes and hypotension including intravenous fluids, attempts at rate control, potentially inotropic therapy, and other measures that have failed. Care must be given to other potentially inciting factors such as sepsis, fluid depletion, or vasodilation.
Rarely, in a patient with an indication for urgent cardioversion, and no alternative treatment options and/or failure to respond to rate control, the need to restore normal sinus rhythm can take precedence over the need for protection from thromboembolic risk with anticoagulation. This is generally not the case and unless severe refractory untreatable hypotension is present, it is prudent to attempt to control the rate first. Cardioversion can be considered when risks of thromboembolic events are minimized. There is little evidence that acute cardioversion improves long-term outcomes. For patients who are selected to undergo urgent or emergent cardioversion, anticoagulation is started as soon as possible but no later than the time of cardioversion. (See 'Anticoagulation' below.)
For patients whose AF is thought to be secondary to an initiating comorbidity such as pneumonia, treatment of the underlying cause of AF is important and may reduce the long-term risk of recurrent AF.
Finally, for those patients who require urgent management, we generally obtain the same baseline diagnostic tests as in stable patients unless other clinical characteristics suggest otherwise. In this case, the diagnostic approach should also include work-up for the suspected underlying condition (eg, pneumonia, pulmonary embolus, etc). (See 'Approach to stable patients' below.)
Indications for hospitalization — Many patients with new onset AF evaluated in an emergency room may not need to be hospitalized. However, indications for hospitalization in these patients include:
●Patients in whom ablation of an accessory pathway is being considered, particularly if the AF was highly symptomatic and associated with hemodynamic collapse and rapid ventricular response rate.
●Severe bradycardia or prolonged pauses.
●Patients with severe bradycardia or prolonged pauses after cardioversion. (See "Sinus node dysfunction: Epidemiology, etiology, and natural history".)
●Treatment of an associated medical problem, which is often the reason for the arrhythmia. Examples include the treatment of hypertension, infection, exacerbation of chronic obstructive pulmonary disease, pulmonary embolism, persistent myocardial ischemia, or acute pericarditis. Patients may be placed in an observation protocol to rule out acute myocardial infarction, and hospitalization is no longer required unless there is ongoing ischemia or suspected acute coronary syndrome that requires intervention. AF alone is not an indication to rule out myocardial infarction. The "rule-out" should be done only if other factors suggest the presence of unstable coronary artery disease.
●Further management of heart failure or hypotension after control of the rhythm or rate
●Initiation of antiarrhythmic drug therapy. Ultimately, the decision to hospitalize needs to take into account patient and drug characteristics.
●Difficult-to-control ventricular rates with evidence of ischemia, congestive heart failure symptoms or signs, and severe symptoms are indications for at least a 24-hour admission.
APPROACH TO STABLE PATIENTS — For stable patients not meeting the above criteria for emergency management, and who present for the first evaluation of new onset AF, we try to accomplish the following in the outpatient setting:
●Perform a complete history and physical examination, including an attempt to obtain old records that might contain information about prior supraventricular arrhythmias and risk factors for AF, as well as disease associations. (See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation", section on 'History and physical examination'.).
●Review a current 12-lead electrocardiogram (ECG) to confirm the diagnosis, determine if atrial flutter or other supraventricular arrhythmias have been present, look for evidence of myocardial ischemia, and consider the presence of other structural abnormalities that may be manifested by the ECG (ventricular hypertrophy, bundle branch block, etc). (See "The electrocardiogram in atrial fibrillation" and "Atrial fibrillation: Overview and management of new-onset atrial fibrillation", section on 'Electrocardiogram'.)
●Obtain a complete blood count, serum electrolytes, and assessment of renal function, particularly in patients for whom a non-vitamin oral anticoagulant might be started. We do not order troponin unless ischemia is suspected.
●Obtain a transthoracic echocardiogram to evaluate associated cardiac conditions (valvular heart disease, cardiomyopathy, or left atrial dilation) even if the physical examination is otherwise normal. This test does not need to be done at the time of the first visit in stable patients. (See "Role of echocardiography in atrial fibrillation".)
●Order tests that evaluate the patient for a predisposing cause.
Thyroid stimulating hormone should be obtained in all patients at least once even if there are no symptoms suggestive of hyperthyroidism (and if thyroid function has not been measured recently). (See "Subclinical hyperthyroidism in nonpregnant adults" and "Cardiovascular effects of hyperthyroidism", section on 'Atrial fibrillation'.)
A chest radiograph in selected patients with evidence of dyspnea and potential heart failure or risk of pneumonia.
●Evaluate the need to slow the ventricular rate. (See 'Rate control' below.)
●Discuss the possible need for cardioversion with the patient. (See 'Cardioversion' below.)
●Determine the need for acute and long-term anticoagulant therapy. (See 'Anticoagulation' below.)
●Discuss the cause (if known) and natural history of AF. (See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation", section on 'Sequelae'.)
●Consider consultation with a cardiologist. Reasons to consult a cardiologist include the need for cardioversion or the need to treat with antiarrhythmic drugs or catheter ablation. (See 'Referral to a cardiologist' below and "Atrial fibrillation: Overview and management of new-onset atrial fibrillation".)
●Schedule follow-up. (See 'Follow-up' below and "Atrial fibrillation: Overview and management of new-onset atrial fibrillation".)
Possible predisposing cause — There are a few clinical situations in which the onset of AF is triggered by another acute medical diagnosis: hyperthyroidism, acute pulmonary embolism, myopericarditis, pneumonia, and after cardiac surgery. Treatment of hyperthyroidism and healing from cardiac surgery, pulmonary embolism, or pericarditis may lead to years or even a lifetime without further episodes of AF. In addition, some patients who develop AF after noncardiac surgery may not develop subsequent AF. In the absence of an acute trigger, risk factors leading to the development of AF include (but are not limited to) the following conditions: advanced age, hypertension, diabetes, obstructive sleep apnea, obesity, heart failure, valvular heart disease, cardiomyopathies, chronic kidney disease, family history, etc [3,4]. For most identified risk factors, we believe that treating the risk factor may reduce but not eliminate the likelihood of subsequent episodes of AF. (See "Epidemiology, risk factors, and prevention of atrial fibrillation".)
With regard to management in patients with an identified predisposing cause:
●Therapy directed at treating a suspected precipitating cause, either prior to possible cardioversion or simultaneous with cardioversion, should be initiated in stable patients and may result in reversion to sinus rhythm.
●For patients with severe hyperthyroidism, the main goal of therapy initially is rate control, anticoagulation, treatment of their hyperthyroidism, and restoration of sinus rhythm once they are euthyroid. (See "Graves' hyperthyroidism in nonpregnant adults: Overview of treatment", section on 'Therapeutic approach'.)
●Treatment of AF in patients with heart failure and/or chronic obstructive pulmonary disease should generally be undertaken simultaneously with treatment of their other condition. In patients with heart failure, restoration of sinus rhythm is the best method for rate control as long as episodic AF does not recur. (See "The management of atrial fibrillation in patients with heart failure", section on 'Correction of reversible causes'.)
Rate control — For most patients with new onset AF and who are in AF at the time of presentation, rate control will precede any attempt to restore sinus rhythm (rhythm control). The principal exception is patients who are hemodynamically unstable after rate control is attempted. The stability of the patient’s condition can be assessed by measurements of respiration rate, patient discomfort and symptoms (including dyspnea and chest discomfort), hypotension, ECG changes consistent with ischemia, oxygen saturation, and chronicity of the problem.
(See 'Patients requiring urgent management' above.).
The average heart rate will generally be above 90 beats per minute. Since the long-term goal is to reduce the heart rate to less than 80 beats per minute, we start rate slowing therapy. In patients with mild to moderate symptoms, slowing the rate often results in significant improvement or even resolution of symptoms. The use of rate slowing medications is discussed in detail elsewhere. (See "Control of ventricular rate in atrial fibrillation: Pharmacologic therapy".)
For patients with a new diagnosis of AF and for whom a rate control strategy has been chosen, oral rate-slowing drugs such as beta blockers or calcium channel blockers are started in the outpatient setting for patients with no or mild symptoms. In patients who are seen in an outpatient setting and who are uncomfortable with their symptoms, consideration should be given to transferring them to a facility capable of treatment with intravenous rate-slowing therapy.
There have been no well-performed studies that can be used to guide recommendations about how quickly the heart rate should be slowed. We reevaluate the patient's heart rate once or twice during the first week and make further adjustments to rate-control therapy as needed. Heart rate logs by an automated blood pressure monitoring device or other device such as a smart phone application or watch technology can be helpful, but are not perfect and are sometimes erroneous. A 24-hour Holter monitor can give more accurate data and also give an average heart rate for the day. An event/loop recorder can also be used to evaluate heart rate over longer periods of time (several days up to one month). Worsening of symptoms should be reported by the patient; this would lead to more aggressive rate slowing.
Longer-term monitoring of heart rate is an option if a patient continues to have symptoms suggestive of uncontrolled or too strictly controlled rates, or if there is a needed change in medication for rate control. This should only be considered for select patients in certain circumstances. The use of patient-recorded heart rate using smart phones, watch technology, or other devices may also have benefit to adjust medical therapy.
Cardioversion — For patients with new onset AF who are hemodynamically stable (with only mild to moderate symptoms) and whose rate is or has been controlled, a decision needs to be made regarding the potential benefit of restoring sinus rhythm. We believe that most patients with new onset AF should have at least one attempt at cardioversion (either electrical or chemical) to sinus rhythm if they do not convert spontaneously on their own. It is important to recognize that AF will spontaneously convert to sinus rhythm within 48 to 72 hours in most patients with new onset AF. Even if cardioversion is contemplated, it often does not need to be performed urgently.
It is important to note that consideration of cardioversion demands that anticoagulation is provided pre- (if >48 hours or unknown duration) and post-cardioversion, regardless of long-term OAC strategy (or CHA2DS2-VASc score), since the acute cardioversion period is associated with increased risk of thromboembolism. (see 'Anticoagulation' below). A detailed discussion of cardioversion, including reasons to not cardiovert, is found elsewhere. (See "Atrial fibrillation: Cardioversion" and "Rhythm control versus rate control in atrial fibrillation", section on 'Summary and recommendations'.)
The choice of electrical or pharmacologic cardioversion requires consideration of the efficacy and safety of the approach, comorbidities, patient stability, patient preference, and comfort of the clinician to use one or the other approach. This issue is discussed in detail elsewhere. (See "Atrial fibrillation: Cardioversion", section on 'Electrical versus pharmacologic cardioversion'.)
The following is the rationale for cardioversion in stable patients:
●Some may never have a second episode, or will have very infrequent episodes.
●Cardioversion will likely improve symptom status, particularly in young people.
●It is also recognized that the duration of continuous AF is a strong predictor of the ability to restore and maintain sinus rhythm. In longstanding persistent AF (6 to 12 months of continuous AF), success in restoring sinus rhythm is markedly reduced [6]. However, the duration of newly diagnosed AF may not be readily apparent in the asymptomatic to minimally symptomatic patient. It is reasonable to attempt cardioversion in the newly diagnosed patient, particularly to determine if any subtle symptoms resolve with the restoration of sinus rhythm, thereby defining if those symptoms were attributable to AF or not. For most patients, an attempt to maintain sinus rhythm is warranted, especially to demonstrate if any subtle symptoms were attributable to AF [6].
The principal discussion of cardioversion in patients with AF is found elsewhere. (See "Atrial fibrillation: Cardioversion".)
Timing — For patients with new onset AF, either early/immediate (within a couple of hours after the diagnosis is made) or later cardioversion, once it is clear the AF episode will not spontaneously convert to sinus rhythm, is an acceptable management strategy, depending on the clinical circumstances and adherence to the pericardioversion principles of anticoagulation. This recommendation is based in part on the results of the Acute Cardioversion Versus Wait And See-approach for Symptomatic Atrial Fibrillation in the Emergency Department (RACE 7 ACWAS) study [7], presented later in this section. In order to determine the optimal management strategy for any patients presenting with an episode of AF, particularly those in an emergency department setting, we suggest early consultation with a cardiologist. Clinical decision making involving the patient, emergency department physician, and cardiologist is necessary for optimal care.
The timing of cardioversion (except in patients who are unstable) is determined in part by the duration of the episode and if there is an acute condition causing AF, and whether the patient has been on anticoagulation for the past three weeks or longer. There is a low risk of systemic embolization if the duration of the arrhythmia is less than 48 hours, and there are no cardiac abnormalities (particularly mitral valve disease or significant left ventricular enlargement due to a cardiomyopathy) on transthoracic echocardiography [8]. A limitation of this 48-hour rule is that it relies on the patient to inform the physician and actually know when the AF episode started. Thus, it is not known whether there is an advantage to immediate rather than delayed cardioversion.
New onset AF (and paroxysmal AF) often spontaneously reverts to normal sinus rhythm, with the incidence of reversion related to the duration of the arrhythmia. This was illustrated in a study of 1822 patients admitted to the hospital because of AF: 356 had an arrhythmia duration less than 72 hours, 68 percent of whom spontaneously reverted to sinus rhythm [9]. Two-thirds of those with spontaneous reversion had AF duration of less than 24 hours, which was the only predictor of spontaneous reversion. Knowing that spontaneous reversion to sinus rhythm occurs in the majority of patients with new onset AF, we generally do not attempt cardioversion within the first 24 hours of onset if the patient is stable. (See "Paroxysmal atrial fibrillation".)
The optimal timing of cardioversion for an episode of AF, whether it be the first or an acute episode, was evaluated in the RACE 7 ACWAS trial [7]. In this study, 437 hemodynamically stable but symptomatic patients with recent onset AF (<36 hours) were randomly assigned in an emergency department to a wait-and-see approach (delayed cardioversion group) or early (immediate) cardioversion on initial presentation. In the delayed cardioversion group, patients were treated with rate control medication only and discharged home when they were asymptomatic, and the rate was less than 110 beats per minute. Patients in this delayed group returned for cardioversion if the AF did not resolve within 48 hours. The rate of the primary end point (the presence of sinus rhythm on an electrocardiogram at four-week follow-up) was not significantly different in the two groups (91 versus 94 percent). In the delayed cardioversion group, conversion to sinus rhythm within 48 hours occurred spontaneously in 69 percent. Thus, some episodes of acute onset AF will stop spontaneously and do not require cardioversion. Therefore, choice of an immediate cardioversion is not required in all patients, and the choice for early cardioversion can depend on clinical circumstances. Other end points are important in patients who have symptomatic AF, including worsening of symptoms and risk for thromboembolic events that can be difficult to assess in a small trial not designed for these considerations.
Most patients with new onset AF of longer than 48 hours duration should have cardioversion postponed until three weeks of effective anticoagulation has been achieved or a transesophageal echocardiogram has been performed and shows no left atrial appendage clot [10]. (See 'Anticoagulation' below.)
Safety — Emergency department or observational unit cardioversion of new onset AF (less than 48 hours duration) is effective and safe [11-14]. This issue was addressed in a study of 289 such patients who were stable, did not have heart disease, and did not have another indication for hospital admission [13]. Pharmacologic cardioversion was attempted in 62 percent and was successful in 50 percent; 28 percent underwent electrical cardioversion with a success rate of 89 percent. Overall, 97 percent of patients were discharged home directly from the emergency department. Similar findings were noted in another small study [14]. (See "Atrial fibrillation: Cardioversion", section on 'Pharmacologic cardioversion'.)
Anticoagulation — For each patient with new onset AF, at least two questions regarding anticoagulation need to be asked:
●Should the patient be anticoagulated immediately? For most patients, the answer is yes. This issue is discussed in detail separately. (See "Prevention of embolization prior to and after restoration of sinus rhythm in atrial fibrillation".)
The two major groups of patients with new onset AF for whom immediate anticoagulation should not be considered are:
•Those for whom the risks exceed the benefits (eg, history of and particularly recent severe bleeding, recent major surgery, inability to comply with medical therapies, or other contraindications to oral anticoagulation).
•CHA2DS2-VASc score of 0 in men or 1 in women who have short paroxysms of AF that self-terminate.
●Does the patient need long-term anticoagulation? For most patients, the answer depends on the CHA2DS2-VASc score. This issue is discussed in detail separately. (See "Atrial fibrillation in adults: Selection of candidates for anticoagulation".)
FOLLOW-UP — Follow-up after an episode of acute AF is necessary to evaluate the safety and efficacy of rate control (see 'Rate control' above) or rhythm control, the compliance of the patient with anticoagulant therapy, the need for these therapies, and the functional status of the patient. For many patients, a one-week follow-up visit, or as soon as possible if one week is not realistic for a particular patient, is a reasonable strategy. This early return is particularly important for patients started on antiarrhythmic drug therapy to assess safety, efficacy, and side effects that can be drug specific.
Following initial pre- and post-cardioversion anticoagulation, the decision to continue long-term anticoagulation following a single reversible incident is debatable and the decision is highly individualized based on the presumed future risk of recurrent AF in that individual (vis a vis CHA2DS2-VASc score). It is also reasonable to take an observational approach following a reversible cause of AF involving clinical follow-up of symptoms and ambulatory monitoring in surveillance for possible recurrence. (See 'Anticoagulation' above.)
REFERRAL TO A CARDIOLOGIST — AF is a common medical problem and can often be managed by primary care physicians without need for consultation with a cardiologist. We suggest patient referral when the physician is not comfortable with decision making or when catheter ablation of AF is under consideration. Also, when cardioversion or antiarrhythmic drugs are contemplated, cardiology consultation is advantageous.
RECOMMENDATIONS OF OTHERS — Recommendations made in this topic are generally consistent with those made by the American Heart Association/American College of Cardiology/Heart Rhythm Society and the European Society of Cardiology [15,16].
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Atrial fibrillation" and "Society guideline links: Arrhythmias in adults".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, “The Basics” and “Beyond the Basics.” The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on “patient info” and the keyword(s) of interest.)
●Basics topic (see "Patient education: Atrial fibrillation (The Basics)")
●Beyond the Basics topic (see "Patient education: Atrial fibrillation (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Initial steps – The early steps in the management of a patient with new onset atrial fibrillation (AF) include an assessment of the need for urgent hospital management (including emergency cardioversion), search for a possible predisposing cause, initiation of rate-slowing therapy, possible cardioversion, and initiation of anticoagulant therapy. (See 'Approach to stable patients' above.)
●Cardioversion
•Urgent or emergency cardioversion – This should be considered for patients with active ischemia, significant hypotension, severe heart failure, or the presence of a preexcitation syndrome associated with rapid conduction using the accessory pathway. (See 'Patients requiring urgent management' above.)
•Elective cardioversion – Most patients with symptomatic new onset AF should have at least one attempt at cardioversion (either electrical or chemical) to sinus rhythm. (See 'Cardioversion' above.)
•Timing of cardioversion – This is determined in large measure by the duration of the episode. (See 'Timing' above.)
●Rate control – Most patients will need to have the ventricular rate in AF slowed to improve symptoms. In patients with no or mild symptoms, we start oral therapy in the office. For patients with bothersome symptoms, we transfer the patient to a facility capable of administering intravenous therapy. (See 'Rate control' above.)
●Anticoagulation – Most patients with new onset AF should be anticoagulated. (See 'Anticoagulation' above.)
ACKNOWLEDGMENT — The UpToDate editorial staff thank Dr. James Hoekstra for his past contributions as a section editor to prior versions of this topic review.
