From the Guidelines
Atrial flutter is a cardiac arrhythmia characterized by rapid, organized atrial contractions at rates of 250-350 beats per minute, resulting from an abnormal electrical circuit in the atria, typically in the right atrium, and creating a reentrant loop that continuously propagates electrical signals, as described in the 2016 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1.
Pathophysiology of Atrial Flutter
Atrial flutter occurs when an abnormal electrical circuit forms in the atria, typically in the right atrium, creating a reentrant loop that continuously propagates electrical signals. This circuit most commonly travels counterclockwise around the tricuspid valve annulus, using the cavotricuspid isthmus as a critical pathway.
Key Characteristics
- The AV node cannot conduct all these rapid atrial impulses to the ventricles, resulting in a functional block that typically allows only every second or fourth atrial impulse to reach the ventricles, creating ventricular rates of about 75-150 beats per minute.
- Atrial flutter often occurs in patients with underlying heart disease, including hypertension, coronary artery disease, valvular disease, or heart failure, which cause atrial enlargement and fibrosis that create the substrate for reentry.
- The rapid atrial rate reduces cardiac output and increases the risk of thrombus formation in the atria, particularly in the left atrial appendage, which can lead to systemic embolization and stroke.
Clinical Considerations
- Atrial flutter can occur in clinical settings similar to those associated with AF, and atrial flutter can be triggered by AT or AF.
- It is common for AF and atrial flutter to coexist in the same patient.
- Patients with atrial flutter are thought to have the same risk of thromboembolism as patients with AF, as noted in the 2016 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1. Some key points to consider in the management of atrial flutter include:
- The use of antiarrhythmic therapy, such as flecainide, propafenone, or amiodarone, which can sometimes convert atrial flutter to AF.
- The role of catheter ablation in treating atrial flutter, particularly in patients with recurrent or persistent atrial flutter.
- The importance of assessing the risk of thromboembolism in patients with atrial flutter and considering anticoagulation therapy as needed.
From the Research
Pathophysiology of Atrial Flutter
- Atrial flutter is a supraventricular tachydysrhythmia believed to arise from electrophysiologic disturbances in the atria 2
- It is due to either a reentry mechanism or an increased atrial automaticity 2
- Atrial depolarization is regular at a rate of 260 to 340 beats per minute 2
- Typical atrial flutter (AFL) is defined as cavotricuspid isthmus (CTI)-dependent macro-re-entrant atrial tachycardia 3
- It occurs in patients with atrial remodeling and shares risk factors with atrial fibrillation 3
- Atrial flutter tends to be an unstable rhythm and is usually associated with intrinsic cardiac or pulmonary disease or adverse extrinsic influences on the heart 2
Mechanisms of Atrial Flutter
- Focal atrial tachycardias arise from automatic, triggered or microreentrant mechanisms 4
- Typical and atypical flutters are macroreentrant in nature 4
- Typical flutter describes a reentrant circuit that is dependent on the cavotricuspid isthmus in the right atrium 4
- Atypical flutter includes various lesional and de novo macroreentrant circuits in the right and left atria 4
Clinical Implications
- Atrial flutter is often associated with increased incidence of atrial fibrillation, stroke, heart failure, and death 3
- It can cause debilitating symptoms, including palpitations, dizziness, syncope, angina, and dyspnea 2
- Electrical cardioversion is the safest and most reliable way of terminating atrial flutter, especially in unstable patients 2
- Catheter ablation has been established as a superior treatment option to medical management in terms of safety, efficacy, and clinical outcomes 3, 5