Atrial Flutter

How atrial flutter works

Normally, each heartbeat starts in the sinus node, a natural pacemaker in the right atrium, and spreads in an orderly way to the ventricles (the lower pumping chambers). In atrial flutter, an electrical wave gets trapped in a circuit and keeps circling the right atrium. In typical atrial flutter, the circuit runs through a narrow strip of tissue called the cavotricuspid isthmus, near the tricuspid valve.

The atria contract roughly 300 times a minute. The AV node, the gatekeeper between atria and ventricles, cannot pass every signal, so it usually lets through every second one (2:1 block). That is why many people with flutter have a pulse of almost exactly 150. Sometimes the ratio changes, causing a variable, irregular pulse.

Atrial flutter vs atrial fibrillation

The two often occur in the same person. Many people with flutter develop atrial fibrillation over the following years, even after successful flutter ablation.

Symptoms

• heart palpitations: a fast, pounding or fluttering heartbeat
• breathlessness, especially on exertion
• tiredness and reduced exercise tolerance
• lightheadedness or dizziness
• chest discomfort or pressure
• fainting, uncommon but more likely if the rate is very fast

Some people, especially older adults, have few symptoms and the rhythm is found on a routine ECG. Persistently fast flutter over weeks can weaken the heart muscle (tachycardia-induced cardiomyopathy), causing heart failure symptoms.

Causes and risk factors

Flutter is most common in older adults and in men. Risk factors include:

• high blood pressure
• coronary artery disease, heart attack and cardiomyopathy
• heart valve disease
• previous heart surgery, including repaired congenital heart disease (which can cause "atypical" flutter around scars)
• lung diseases such as COPD, and pulmonary embolism
• hyperthyroidism
• obstructive sleep apnea, obesity and heavy alcohol use
• recent surgery or acute illness

Diagnosis

• ECG: the key test. It shows the classic sawtooth flutter waves, best seen in leads II, III and aVF.
• Ambulatory monitoring: a Holter monitor, patch or event recorder if episodes come and go.
• Echocardiogram: checks heart function, valves and the size of the atria.
• Blood tests: thyroid function, electrolytes, kidney function and blood count.
• Sleep study if sleep apnea is suspected.

Treatment

Stroke prevention

Blood thinners (anticoagulants) are recommended based on the same stroke-risk score used for atrial fibrillation (CHA2DS2-VASc), which counts factors such as age, high blood pressure, diabetes, heart failure and previous stroke. Direct oral anticoagulants are commonly used. Anticoagulation is also needed for at least several weeks around cardioversion.

Controlling the heart rate

Beta-blockers or calcium channel blockers such as diltiazem slow the conduction through the AV node. Flutter is often harder to rate-control with medicines than atrial fibrillation.

Restoring normal rhythm

• Electrical cardioversion: a brief, controlled shock under sedation. It works very well for flutter, often at low energy.
• Antiarrhythmic medicines can restore or maintain rhythm, but they are less effective for flutter than ablation and some can be risky.

Catheter ablation

In ablation, thin wires are passed through a vein in the groin to the heart, and a line of scar is created across the cavotricuspid isthmus to break the circuit. For typical flutter, it succeeds in more than 9 in 10 people and is often recommended as first-line treatment for recurrent or symptomatic flutter. Recovery is usually quick, with many people home the same or next day.

Treating the triggers

Managing blood pressure, sleep apnea, thyroid disease, alcohol intake and weight lowers the chance of recurrence and of developing atrial fibrillation.

Complications

• Stroke and other blood clots
• Heart failure from a persistently fast rate
• Fainting and falls
• Side effects of treatment, including bleeding on blood thinners

Outlook

Atrial flutter is very treatable. Ablation cures typical flutter in most people, though atrial fibrillation may appear later, so follow-up continues. Decisions about stopping blood thinners after ablation depend on overall stroke risk and are made with a cardiologist.

Frequently asked questions

Is atrial flutter dangerous?

It is not usually immediately life-threatening, but it needs treatment. It raises the risk of stroke and, if the heart rate stays fast, can weaken the heart. Chest pain, fainting or severe breathlessness with flutter need emergency care.

What is the difference between atrial flutter and atrial fibrillation?

In atrial flutter, the upper chambers beat fast in an organized loop, usually giving a regular pulse. In atrial fibrillation, the activity is chaotic and the pulse is irregular. Both raise stroke risk and are treated with similar medicines, but ablation works especially well for flutter.

Can atrial flutter go away on its own?

Some episodes stop by themselves within hours, particularly when triggered by illness, surgery or alcohol. Persistent or recurring flutter usually needs cardioversion or ablation. Do not ignore an episode just because it stops.

Do I need blood thinners for atrial flutter?

Many people do. The decision is based on stroke-risk factors such as age, high blood pressure, diabetes, heart failure and previous stroke. Your doctor will calculate your risk and weigh it against bleeding risk.

Can you live a normal life with atrial flutter?

Yes. With treatment, especially ablation for typical flutter, most people return to normal activity, including exercise. Ongoing check-ups monitor for atrial fibrillation and manage risk factors.