Atrial fibrillation vs atrial flutter: what’s the difference?

For the average individual, the terms atrial fibrillation and atrial flutter appear equal. However, this is not the case. Leading consultant cardiologist Dr Idris Harding discusses the differences between the two terms.

What is the difference between atrial fibrillation and atrial flutter?

The terms "atrial fibrillation" and "atrial flutter" are frequently used interchangeably, causing some ambiguity even among medical professionals regarding the boundary between these conditions. It is crucial to distinguish between these two diagnoses, as there are significant differences in symptoms, prognosis, and treatment options for these distinct rhythm problems.

Much of the confusion in this domain arises due to the somewhat imprecise use of the term "flutter" by both patients and medical professionals. I often encounter patients who describe sensations in their chest as a "flutter."

There's nothing inherently incorrect about using this term; if you feel a "flutter in your chest," no one, including myself, is in a position to tell you that you are wrong. The confusion arises when doctors adopt your terminology for the symptom to describe the arrhythmia's mechanism, known as "pathophysiology."

When should the term “flutter” be used?

From a pathophysiological standpoint, the term "flutter" should be reserved for describing a specific arrhythmia mechanism under precise conditions. For an abnormal heart rhythm to be labelled as "flutter," it must be fast, sustained, and result from a continuous, repetitive conduction of electricity along a singular electrical circuit within a specific heart chamber. This phenomenon is commonly known as "typical atrial flutter."

Typical atrial flutter originates from a consistent anatomical and electrical feature present in the right atrium of nearly every human heart. Consequently, this form of "flutter" occurs in the same location, at the same pace, and induces similar symptoms in most individuals affected by it. In typical atrial flutter, the atria (upper chambers) cause the atria (upper chambers) to race at around 300 bpm, in a way that is that it is self-perpetuating to race at approximately 300 beats per minute, exhibiting a self-perpetuating nature.

Once the electrical circuit completes one cycle, it continues repetitively without a clear reason for cessation. This ongoing cycle can lead to issues such as a persistent elevation in heart rate, breathlessness, an unresponsive heart rate during exercise, and, if prolonged, eventual fatigue and failure of the heart's lower chambers.

How can the arrhythmia be recognised and cured?

Due to the fact that atrial flutter is caused by the same part of the heart in everyone who gets it, we as cardiologists have developed effective methods for identifying this arrhythmia through the distinctive pattern it creates on an electrocardiogram (ECG). The cure involves an ablation procedure designed to cauterise the specific area of the heart responsible for the condition.

The likelihood of a lasting positive outcome from an ablation for typical atrial flutter is approximately 98%. In other words, among every 100 patients undergoing this procedure, only about two are expected to experience a recurrence of the issue. This success rate sets it apart from many other ablation procedures, especially when compared to conditions like atrial fibrillation.

While there is an undeniable connection between atrial flutter and atrial fibrillation—approximately 40% of patients initially diagnosed will go on to be diagnosed with atrial fibrillation at a later date. However, despite occurring in the same patients, and having common causes, these two rhythms have extensive differences.

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