Atrial flutter (AFL) is a tachyarrhythmia arising in the atrium, characterized by rapid, regular atrial depolarization (commonly 250-350 beats per minute [bpm]). Atrioventricular conduction usually occurs in a 2:1 ratio, resulting in a ventricular rate one-half of the atrial rate. AFL may exist as an individual rhythm in a patient or may vacillate with other supraventricular tachycardias (most commonly with atrial fibrillation).
The exact incidence of AFL in the general population is unknown, but incidence increases with age. The condition is more prevalent in men than in women by a ratio of up to 2:1.
Most cases of AFL are associated with an underlying condition, many of which are also associated with atrial fibrillation, though the latter is more common. Cases of AFL without an identifiable predisposing factor ("lone atrial flutter") are far less common.
Common causes and predisposing conditions include:
A classification of AFL was defined by Wells et al in 1979, distinguishing two types:
Type I (typical, common, or counterclockwise isthmus-dependent) – Characterized by a circuit from the high right atrium, down the lateral wall, crossing the isthmus between the orifice of inferior vena cava and the annulus of the tricuspid valve. Slow conduction through the isthmus causes an excitable gap that allows the flutter wave to repeatedly depolarize the atrium, propagating the arrhythmia. Less often, the isthmus-dependent pathway rotates in the opposite direction, which results in "atypical" or "clockwise" type I flutter.
Type II – Not fully characterized and broadly defined as an atrial tachycardia with the characteristic continuous, undulating pattern on ECG that does not fit the typical clockwise or counterclockwise flutter pattern. It is less frequent and usually has a higher atrial rate (greater than 350 bpm).
Patients may be asymptomatic, with the rhythm being discovered on a routine physical examination or ECG. In other cases, mild symptoms such as fatigue, dyspnea, chest discomfort, palpitations, or sensation of an irregular heartbeat may be present. Patients may also present with symptoms and signs of cardiac decompensation and poor end-organ perfusion such as dyspnea, dizziness, syncope, and chest pain. They can also have symptoms of thromboembolic complications of AFL such as focal neurological deficits suggestive of a transient ischemic attack (TIA) or stroke, or pleuritic chest pain and dyspnea from pulmonary embolism (PE).
ICD10CM: I48.92 – Unspecified atrial flutter
SNOMEDCT: 5370000 – Atrial Flutter
Differential Diagnosis & Pitfalls
Sinus tachycardia – Will have a normal P wave (absent flutter waves) before each QRS complex on the ECG; however, they can be difficult to see if the heart rate (HR) is very fast. The HR usually slows down slightly after carotid sinus massage, with no abrupt changes in the rate. Usually a precipitating cause for sinus tachycardia is present, such as anxiety, stress, exercise, or any other reason for catecholamine surge. S1 is constant, and a waves are normal on jugular venous pulse (JVP).
Atrial fibrillation – No P waves on ECG, rhythm irregularly irregular. Precipitating cause such as stress, alcohol, or other stimulants (incidence of AFL is not increased with caffeine). Variable S1 and absent a waves on JVP.
Premature atrial complexes – Premature P wave on the ECG, which is usually different in morphology from the normal sinus P wave. Precipitating factors mentioned above may be present.
Atrial tachycardia – Atrial rate of, usually, 150-200 bpm, and the P wave morphology is different from the normal sinus P wave. Variable degree of AV block maybe present. Variable intensity of S1 and a waves on JVP.
Ventricular tachycardia – Absent P waves with wide QRS complex with a ventricular rate of 100-250 bpm on ECG. Most common predisposing condition is ischemic heart disease. If sustained, is life-threatening.
Pre-excitation arrhythmias – Occur because of an accessory conducting pathway that connects the atria to the ventricles and bypasses the AV node. The most common example is WPW syndrome. PR interval is usually short due to the presence of a delta wave, which is an initial slurred upslope of the QRS complex. ST-T wave changes opposite in direction from the wide QRS complex are also present.
Drug Reaction Data
Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.