Atrial flutter: Overview of diagnosis and management

INTRODUCTION — 

Atrial flutter is a cardiac arrhythmia characterized by rapid, regular atrial depolarizations at a characteristic rate of approximately 300 beats/min and a typically regular ventricular rate of approximately 150 beats/min (image 1).

This topic will discuss the epidemiology, clinical presentation, diagnosis, and management of atrial flutter. Other topics discuss management issues in detail.

●(See "Electrocardiographic and electrophysiologic features of atrial flutter".)

●(See "Control of ventricular rate in atrial flutter" and "Atrial flutter: Maintenance of sinus rhythm".)

●(See "Atrial flutter: Risk of thromboembolism and role of anticoagulation".)

The risk of developing atrial flutter increased 3.5 times (p<0.001) in subjects with heart failure (HF) and 1.9 times (p<0.001) for subjects with chronic obstructive pulmonary disease. Among those with atrial flutter, 16 percent were attributable to HF and 12 percent to chronic obstructive pulmonary disease. Three subjects (1.7 percent) without identifiable predisposing risks were labeled as having "lone atrial flutter."

EPIDEMIOLOGY — 

Atrial flutter is less common than atrial fibrillation, but it occurs in many of the same clinical settings as atrial fibrillation and is often associated with atrial fibrillation. It may also be associated with other supraventricular arrhythmias. Atrial flutter may be a stable rhythm, a bridge arrhythmia between sinus rhythm and atrial fibrillation, or an organized rhythm in atrial fibrillation patients treated with antiarrhythmic drugs.

In a population-based study of 58,820 adults, the incidence of new atrial flutter was 88/100,000 person-years [1]. Based upon these data, it was estimated that the incidence of atrial flutter in the United States is approximately 200,000 new cases per year.

Similar to atrial fibrillation, the risk of atrial flutter increases with age. In the above-cited study, the incidence of atrial flutter ranged from 5 per 100,000 person-years for individuals under age 50 to 587 per 100,000 person-years for those over age 80 [1]. The incidence of atrial flutter was 2.5 times higher in males compared with females [1].

Atrial flutter is usually associated with cardiac or pulmonary disease and is rare in individuals with no concurrent conditions [1-3]. (See 'Associated conditions' below.)

In the above series, only 1.7 percent of cases of atrial flutter occurred in adults with no concurrent cardiopulmonary disease (previously termed "lone atrial flutter") [1]. In a series of 380 children and young adults with atrial flutter, a higher rate of atrial flutter without concurrent cardiac disease (8 percent) was identified [3].

ASSOCIATED CONDITIONS — 

Atrial flutter is usually associated cardiac and/or pulmonary disease. A variety of underlying conditions can predispose to the development of atrial flutter. These include:

●Heart disease – Atrial flutter is commonly associated with heart disease, such as valvular heart disease, HF, and hypertensive heart disease. In the above-cited population-based study, the risk of developing atrial flutter was 3.5 times higher in individuals with HF [1].

Atrial flutter is a relatively uncommon complication of an acute myocardial infarction [4,5]. (See "Supraventricular arrhythmias after myocardial infarction".)

●Respiratory disorders – In the above-cited population-based study, the risk of developing atrial flutter was 1.9 times higher in individuals with chronic obstructive pulmonary disease [1].

●Post-cardiac surgery – Atrial flutter can occur after cardiac surgery (including surgical repair of congenital heart disease), both as an early postoperative complication and as a late arrhythmia. Atrial flutter in this setting may be typical (cavotricuspid isthmus dependent) or atypical. The macroreentrant circuits are usually right atrial, related to anatomic obstacles and surgical scars (eg, right atriotomy scar, atrial septal defect repair). (See "Atrial fibrillation and flutter after cardiac surgery", section on 'Pathogenesis'.)

●After treatment for atrial fibrillation – Atrial flutter may develop after drug treatment or ablation for atrial fibrillation.

•Antiarrhythmic drugs – Atrial flutter may occur after initiation of an antiarrhythmic drug for the suppression of atrial fibrillation. It may occur in up to 15 percent of patients treated with flecainide or propafenone and is also seen in patients treated with dronedarone or amiodarone.

●Post-atrial fibrillation ablation – Some patients develop atypical left atrial flutter (eg, mitral isthmus flutter) after atrial fibrillation ablation. These arrhythmias may be promoted by circuits created by incomplete ablation lines created by left atrial ablation but are often amenable to ablation themselves. This issue is discussed in detail separately. (See "Atrial fibrillation: Catheter ablation", section on 'Arrhythmic complications'.)

●Other triggers – Atrial flutter may occur with any of the conditions that cause atrial fibrillation, including thyrotoxicosis, hypertension, obesity, obstructive sleep apnea, sinus node dysfunction, pericarditis, pulmonary disease, pulmonary embolism, pulmonary hypertension, kidney disease and traumatic brain injury. (See "Epidemiology, risk factors, and prevention of atrial fibrillation".)

CLASSIFICATION — 

Atrial flutter is classified as either typical or atypical (see 'Typical atrial flutter' below and 'Atypical atrial flutter' below). This classification is important for management given the efficacy of ablation for typical atrial flutter. (See "Atrial flutter: Maintenance of sinus rhythm", section on 'RF catheter ablation'.)

The previous classification of type I or type II atrial flutter is no longer used.

Typical atrial flutter — "Typical" atrial flutter involves a macroreentrant circuit traversing the cavotricuspid isthmus (CTI) (figure 1). The CTI is the region of right atrial tissue between the orifice of the inferior vena cava and the tricuspid valve annulus (figure 2). Typical atrial flutter is also known as CTI-dependent atrial flutter. There are two types of typical atrial flutter which can generally be distinguished by their electrocardiographic (ECG) appearance.

●Typical atrial flutter – The circuit for atrial flutter is usually a counterclockwise rotation around the tricuspid valve (figure 2), exhibiting a negative sawtooth appearance in the inferior ECG leads (II, III, and aVF) and positive sawtooth appearance in lead V1 (image 1).

●Reverse typical atrial flutter – If the circuit is clockwise, it is called "reverse" or "clockwise" typical flutter, exhibiting positive flutter waves in the inferior ECG leads and negative flutter waves in lead V1 (image 2). The clockwise circuit occurs far less frequently than the counterclockwise circuit.

Rare patients with typical atrial flutter exhibit both counterclockwise and clockwise circuits at different times. (See 'Diagnosis' below.)

Atypical atrial flutter — Atrial flutter not involving the CTI is called "atypical" atrial flutter (or noncavotricuspid isthmus-dependent macroreentrant atrial tachycardia). In atypical atrial flutters, the flutter waves in the inferior leads and lead V1 are often concordant (image 3). Atypical atrial flutter can involve any region of the right or left atria, around areas of scar tissue due to intrinsic heart disease or surgical/ablated scar tissue. (See "Electrocardiographic and electrophysiologic features of atrial flutter".)

HEMODYNAMIC EFFECTS — 

Hemodynamic changes occur with atrial flutter largely due to rapid atrial and ventricular rates. These changes include an increase in the mean right and left atrial pressures, a reduction in right and left ventricular end-diastolic pressures, a decrease in systolic blood pressure, and an increase in diastolic pressure [6]. The cardiac index is generally unaltered. The reduction in left ventricular pressure is a result of the rapid heart rate, while the increase in atrial pressure is due, in part, to contraction against closed atrioventricular (AV) valves. The hemodynamic changes lead to the symptoms presented below. (See 'Clinical presentation' below.)

CLINICAL MANIFESTATIONS

Clinical presentation

History — Patients with atrial flutter generally have one or more symptoms such as palpitations, dyspnea on exertion, lightheadedness, chest pain, and fatigue [7]. Less common symptoms include severe dyspnea, hypotension, anxiety, presyncope, or syncope. These symptoms are largely attributable to the rapid heart rate. (See 'Hemodynamic effects' above.)

The history and medical record review aid in identifying the onset of the arrhythmia, its frequency and duration, precipitating causes and modes of termination, prior response to drug therapy, and the presence of heart disease or potentially reversible causes. (See 'Associated conditions' above.)

Physical examination — The physical examination during atrial flutter may reveal tachycardia (with a regular or irregular pulse), hypotension, diaphoresis, and/or evidence of HF. (See "Heart failure: Clinical manifestations and diagnosis in adults", section on 'Physical examination'.)

Cardiac auscultation may reveal an irregular rhythm, a murmur (which may suggest concurrent valve disease), and a gallop.

Flutter waves may be seen in the jugular veins at a rate consistent with the atrial rate.

Wearable devices — On wearable devices, atrial flutter may be recorded as a regular or irregular rhythm. When the ventricular response is regular, the atrial flutter may sometimes be mistaken for sinus rhythm.

DIAGNOSIS

Electrocardiogram — In patients with atrial flutter, a 12-lead ECG is generally diagnostic, showing characteristic atrial flutter waves and ventricular rate (image 1 and image 2 and image 3). (See 'Atrial flutter waves' below and 'Ventricular rate' below.)

Atrial flutter waves — The diagnosis of atrial flutter is almost always secured by the observation of a characteristic pattern on the ECG, which includes the presence of continuous, regular atrial electrical activity with an atrial rate of approximately 300 beats/min (range 240 to 340). Typical P waves are absent, and the atrial activity is seen as a sawtooth pattern (also called F waves) in leads II, III, and aVF.

As noted above, the ECG hallmark of typical atrial flutter is discordance in flutter wave "direction" between the inferior leads and lead V1 (see 'Typical atrial flutter' above). In counterclockwise circuits, flutter waves are directly negative in the inferior leads but are positive in lead V1 (image 1). In clockwise circuits, the opposite is true. These ECG rules are generally less reliable after atrial ablation or surgery.

Ventricular rate — With atrial flutter, the ventricular rate is typically 150 beats/min with 2:1 conduction across the AV node, in the absence of AV node dysfunction or AV nodal blockers. Even atrial to ventricular rate ratios (eg, 2:1 or 4:1 conduction) are much more common than odd ratios (eg, 3:1 or 5:1). Odd ratios probably reflect bilevel block in the AV node.

Higher conduction ratios may indicate significant conduction system disease that may manifest after cardioversion.

On the other hand, a 1:1 response suggests catecholamine excess, parasympathetic withdrawal, the presence of antiarrhythmic drug therapy with Class IA or IC agents (table 1), or the existence of an accessory bypass tract. (See "Electrocardiographic and electrophysiologic features of atrial flutter".)

Concurrent conditions — The ECG may also identify concurrent conditions such as left ventricular hypertrophy, bundle branch block, prior myocardial infarction, or preexcitation. Overlapping flutter waves may complicate assessment of the QT interval, repolarization pattern, and T waves.

Ambulatory ECG monitoring — Holter monitoring or event recorders are used to identify the arrhythmia if symptoms are nonspecific, to identify triggering events, to detect associated atrial arrhythmias (such as atrial fibrillation), and to determine average and peak heart rates. (See "Ambulatory ECG monitoring".)

DIFFERENTIAL DIAGNOSIS — 

Atrial flutter should be distinguished from other causes of similar ECG findings. These include (see "Narrow QRS complex tachycardias: Clinical manifestations, diagnosis, and evaluation", section on 'Types of narrow QRS complex tachycardia'):

●Atrial fibrillation – There is an absence of organized atrial activity in atrial fibrillation.

●Other types of supraventricular tachycardia – Focal atrial tachycardia with AV block may mimic atypical atrial flutter by ECG appearance. (See "Focal atrial tachycardia".)

●Artifact – ECG artifact (eg, caused by a tremor) may mimic the atrial flutter [8].

The above conditions can generally be distinguished from atrial flutter by careful examination of the 12-lead ECG. If the type of arrhythmia remains uncertain, an electrophysiology study is rarely necessary to determine if the arrhythmia is atrial flutter. (See "Invasive diagnostic cardiac electrophysiology studies".)

DIAGNOSTIC EVALUATION

Echocardiogram — A transthoracic echocardiogram (TTE) should be obtained in all patients with atrial flutter to evaluate the size of the right and left atria, the size and function of the right and left ventricles, and to detect possible valvular heart disease, congenital heart disease, pericardial disease, or left ventricular hypertrophy.

TTE has a low sensitivity for detecting atrial thrombus, and transesophageal echocardiography (TEE) is preferred for this purpose. Thus, TEE may play an important role in the selection of patients for cardioversion, as it does in atrial fibrillation. (See "Atrial flutter: Restoration of sinus rhythm" and "Role of echocardiography in atrial fibrillation".)

Additional testing — Serum electrolytes, kidney (serum blood urea nitrogen and creatinine) and hepatic function (SGOT), and thyroid function tests are ordered to evaluate for predisposing conditions. Pulmonary function is evaluated if lung disease is suspected.

Exercise testing is sometimes useful to reproduce exercise-induced atrial flutter, to evaluate for associated ischemic heart disease, or to determine the maximum heart rate with exercise, which can help guide medical therapy.

COMPLICATIONS — 

Complications of atrial flutter include myocardial ischemia, presyncope, syncope, HF (with either reduced or preserved left ventricular ejection fraction), stroke, and systemic thromboembolism.

MANAGEMENT OVERVIEW — 

There are four major issues that must be considered in the management of atrial flutter, as for atrial fibrillation:

●Control of the ventricular rate (see "Control of ventricular rate in atrial flutter")

●Restoration of normal sinus rhythm (NSR) (see "Atrial flutter: Restoration of sinus rhythm")

●Maintenance of NSR (see "Atrial flutter: Maintenance of sinus rhythm")

●Prevention of systemic embolization (see "Atrial flutter: Risk of thromboembolism and role of anticoagulation")

These treatment issues are briefly summarized here and are discussed in detail separately.

In patients with atrial flutter, control of the ventricular rate or reversion to normal sinus rhythm will reduce symptoms (such as palpitations and dyspnea) and also prevent arrhythmia-induced cardiomyopathy (see "Arrhythmia-induced cardiomyopathy"). For patients with HF, rate control reduces HF symptoms, but rhythm control may be more effective for symptom control. Effective maintenance of sinus rhythm, most commonly with ablation, frequently leads to clinical improvement and may improve left ventricular systolic function. (See "Arrhythmia-induced cardiomyopathy".)

Rate control — Atrial flutter is commonly acutely managed with rate control. Rate control in atrial flutter, as in atrial fibrillation, usually involves the administration of a nondihydropyridine calcium channel blocker or a beta blocker. Digoxin is used less often because its major action is an enhancement of vagal tone, which is offset during exertion. Amiodarone is rarely used (eg, for treatment of acutely ill patients) but it may promote reversion to sinus rhythm. Since cardioversion is associated with an increased risk of thromboembolism, amiodarone use is avoided in patients who are not candidates for conversion to sinus rhythm because of inadequate anticoagulation. (See "Control of ventricular rate in atrial flutter".)

However, it is more difficult to affect rate control in atrial flutter compared with atrial fibrillation. While up-titration of AV nodal blocking agents typically lowers the mean rate in atrial fibrillation, patients with atrial flutter are frequently "stuck" at 2:1 AV conduction. Therefore, early electrical cardioversion (with appropriate anticoagulation) is commonly performed in patients with atrial flutter.

Rhythm control

Restoration of sinus rhythm — The urgency of restoration of sinus rhythm depends upon the clinical presentation. (See "Atrial flutter: Restoration of sinus rhythm".)

●Hemodynamically unstable patients - Patients with atrial flutter who have a rapid ventricular rate (100 beats/min) and significant hemodynamic compromise (hypotension or HF) are treated with urgent cardioversion.

In patients with atrial flutter and hemodynamic compromise, but with a controlled ventricular rate (≤100 beats/min), explanations for hemodynamic instability other than the atrial flutter should be sought. Restoration of sinus rhythm in these patients may not necessarily improve the clinical status.

●Hemodynamically stable patients

•Without ventricular preexcitation – For hemodynamically stable, minimally symptomatic patients without ventricular preexcitation, watchful waiting with anticoagulation and rate control medicines (see 'Rate control' above) may be reasonable, as atrial flutter may convert to sinus rhythm spontaneously. Cardioversion is also reasonable in this setting.

•With ventricular preexcitation – Most patients with atrial flutter who have an accessory pathway with ventricular preexcitation should undergo immediate cardioversion. AV node-specific antiarrhythmic drugs that are normally used to control the ventricular rate during atrial flutter or atrial fibrillation (table 2) can paradoxically increase the ventricular response to preexcited atrial flutter and are generally contraindicated for patients with preexcited atrial flutter. (See "Treatment of arrhythmias associated with the Wolff-Parkinson-White syndrome".)

For patients treated with cardioversion, synchronized internal or external direct current is generally preferred to antiarrhythmic drug cardioversion. Atrial overdrive pacing is a less commonly used method for cardioversion used primarily in patients with permanent or temporary atrial pacing leads. (See "Atrial flutter: Restoration of sinus rhythm".)

When electric or pharmacologic cardioversion is performed, precautions should be taken with regard to anticoagulation and TEE if the duration of atrial flutter is beyond 24 to 48 hours or of unknown duration. (See "Atrial flutter: Risk of thromboembolism and role of anticoagulation".)

Maintenance of sinus rhythm — Atrial flutter frequently recurs in patients without a correctable cause. For most patients with atrial flutter, definitive treatment with catheter ablation is preferred to long-term treatment with antiarrhythmic drugs. (See "Atrial flutter: Maintenance of sinus rhythm".)

Prevention of systemic embolization — The risk of systemic thromboembolism and the role of anticoagulation in reducing this risk in patients with atrial flutter is discussed separately. (See "Atrial flutter: Risk of thromboembolism and role of anticoagulation".)

In patients with atrial flutter and/or atrial fibrillation who have contraindications to anticoagulation, left atrial appendage occlusion is a potential alternative means of decreasing the risk of thromboembolism. (See "Atrial fibrillation: Left atrial appendage occlusion".)

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 5^th to 6^th 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 10^th to 12^th 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 topics (see "Patient education: Atrial flutter (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Definition – Atrial flutter is an abnormal cardiac rhythm characterized by rapid, regular atrial depolarizations at a characteristic rate of approximately 300 beats/min and a regular ventricular rate of approximately 150 beats/min (image 1). (See 'Introduction' above and 'Classification' above.)

●Epidemiology – Atrial flutter is less common than atrial fibrillation, but it occurs in many of the same clinical settings as atrial fibrillation and is often associated with atrial fibrillation. Atrial flutter is usually associated with cardiac or pulmonary disease and is rare in individuals with no concurrent conditions. Conditions associated with atrial flutter include valvular heart disease, heart failure (HF), post-cardiac surgery, pericardial disease, and respiratory disorders. (See 'Epidemiology' above and 'Associated conditions' above.)

●Classification – Atrial flutter is classified as either typical (image 1 and image 2) or atypical (image 3). This classification is important for management, particularly given the efficacy of ablation for typical atrial flutter. (See 'Classification' above and "Atrial flutter: Maintenance of sinus rhythm", section on 'RF catheter ablation'.)

●Clinical manifestations – The clinical manifestations of atrial flutter are similar to those of atrial fibrillation. (See 'Clinical manifestations' above.)

•Symptoms – Typical complaints include palpitations, dyspnea on exertion, lightheadedness, chest pain, and fatigue. (See 'History' above.)

•Physical examination – This may reveal tachycardia, hypotension, diaphoresis, and evidence of HF. Occasionally, cardiac auscultation may reveal an irregular rhythm, a murmur (which may suggest concurrent valve disease), and a gallop. Flutter waves may be seen in the jugular veins at a rate consistent with the atrial rate. (See 'Physical examination' above.)

●Diagnosis – The diagnosis can usually be made from a 12-lead ECG showing characteristic atrial flutter waves and ventricular rate (image 1 and image 2 and image 3). (See 'Diagnosis' above.)

●Management – There are four major issues that must be considered in the management of atrial flutter, as for atrial fibrillation:

•Control of the ventricular rate (see "Control of ventricular rate in atrial flutter")

•Restoration of normal sinus rhythm (NSR) (see "Atrial flutter: Restoration of sinus rhythm")

•Maintenance of NSR (see "Atrial flutter: Maintenance of sinus rhythm")

•Prevention of thromboembolization (see "Atrial flutter: Risk of thromboembolism and role of anticoagulation")

ACKNOWLEDGMENT — 

The UpToDate editorial staff acknowledges Leonard Ganz, MD, FHRS, FACC, who contributed to an earlier version of this topic review.