Snapshot A 64-year-old woman presents to the emergency room for several hours of lightheadedness and palpitations. Her past medical history includes hypertension, mitral valve regurgitation, and chronic obstructive pulmonary disease. On physical exam, her pulse is around 150/min. An electrocardiogram is administered, revealing a narrow complex tachycardia and sawtooth-like waves in leads II, III, and aVF. Introduction Clinical definition a supraventricular tachycardia characterized by a “sawtooth” appearance, regular rhythm some atrioventricular (AV) node conduction block Associated conditions chronic obstructive lung disease pulmonary embolism thyrotoxicosis alcohol use mitral valve disease Epidemiology Risk factors chronic lung disease heart disease Etiology Pathogenesis large re-entrant circuit, typically in the right atrium Presentation Symptoms syncope palpitations fatigue poor exercise tolerance Physical exam pulse is often around 150/min blood pressure may or may not be decreased Imaging Transthoracic echocardiography (TTE) indications initial imaging for evaluation of atrial size and function may also help diagnosis any valvular disease or thrombus Studies Electrocardiogram (ECG) indication all patients findings narrow complex tachycardia ventricular rate 125-150/min regular atrial rate 250-300/min (usually a 2:1 AV block) flutter waves or “sawtooth” waves in leads II, III, and aVF Adenosine administration indication if ECG is unclear adenosine transiently blocks atrioventricular node atrial flutter is more easily diagnosed on ECG Making the diagnosis based on clinical presentation and ECG Differential Atrial fibrillation distinguishing factor irregularly irregular rhythm Multifocal atrial tachycardia (MAT) distinguishing factor irregularly irregular rhythm with discrete polymorphic P waves Treatment Management approach treatment for atrial flutter is the same as atrial fibrillation except that catheter ablation is a definitive therapy for atrial flutter Medical rate control indication all patients drugs calcium channel blockers β-blockers digoxin rhythm control indication for patients who are contraindicated to catheter ablation therapy anticoagulation indication once rate has been controlled for patients who meet the criteria according to the CHA2DS2-VASc score drugs aspirin warfarin dabigatran rivaroxaban apixaban Non-operative synchronized cardioversion indication unstable patients Operative catheter ablation indication definitive treatment outcomes often superior in the long-term to therapies targeting rate-control or rhythm-control Complications Embolization Heart failure Prognosis Depends on underlying comorbidities