Atrial Flutter

What is atrial flutter?

Atrial flutter occurs when an abnormal electrical circuit loops continuously around the upper chambers of the heart, causing the atria to beat very rapidly — typically 250 to 350 times per minute. The ventricles (lower chambers) usually beat at half that rate because the AV node acts as a gatekeeper, blocking some signals. The result is often a heart rate of around 150 beats per minute — fast enough to cause significant symptoms and, if prolonged, can weaken the heart muscle over time.

There are two distinct types of atrial flutter, and it is important to understand the difference — because they have different causes, different complexity, and different approaches to treatment.

Typical Flutter — the common form

Typical atrial flutter follows a fixed, predictable electrical circuit that loops around the tricuspid valve in the right atrium. The circuit always passes through a specific narrow channel called the cavotricuspid isthmus (CTI) — and this is its weakness. Because the circuit is consistent and well-defined, it is one of the most reliably curable arrhythmias in all of electrophysiology.

Treatment: catheter ablation

A single ablation procedure targeting the cavotricuspid isthmus creates a line of scar tissue that blocks the circuit permanently. Cure rates exceed 90%. Most patients go home the same day and never experience typical flutter again. This is one of the most satisfying procedures in EP — a definitive cure in the vast majority of patients.

Atypical Flutter — the more complex form

Atypical flutter is a broader category that covers any flutter circuit that does not follow the standard cavotricuspid isthmus route. Instead of using a fixed anatomical channel, atypical flutter circuits form around areas of scar tissue — and that scar can be located anywhere in the upper chambers of the heart.

Scar tissue in the atria can result from prior heart surgery (such as valve repair or congenital heart disease corrections), prior catheter ablation, prior AFib, or from cardiomyopathy and fibrosis. Because the circuit depends on where the scar happens to be, atypical flutter circuits are highly variable from patient to patient — they can form in the right atrium, the left atrium, or both.

Treatment: catheter ablation

Atypical flutter can be treated with catheter ablation, but the procedure is significantly more complex than typical flutter ablation. It requires detailed 3D electroanatomical mapping to identify the specific scar-based circuit driving the arrhythmia in that individual patient. Once the circuit is mapped, ablation targets the critical isthmus within or around the scar. Success rates are good but vary depending on the complexity of the underlying substrate.

Medications

For both types of flutter, rate-controlling medications can slow the ventricular rate and reduce symptoms, but they do not eliminate the flutter circuit. Antiarrhythmic medications may reduce recurrence but are generally not a long-term solution. Ablation remains the preferred definitive treatment.

Stroke prevention in atrial flutter

Like AFib, atrial flutter increases the risk of stroke. Anticoagulation decisions are made based on your individual stroke risk profile — not solely on whether you are in flutter or normal rhythm. Your electrophysiologist will assess this carefully.

What are the symptoms?

• Rapid or fluttering heartbeat — often very regular, unlike AFib
• Shortness of breath
• Fatigue and reduced exercise tolerance
• Chest pressure or discomfort
• Dizziness
• Some patients feel very little and are diagnosed incidentally on an ECG