Atrial Flutter- AFs little brother

You have two types of doctors- those who care about the difference between atrial flutter and atrial fibrillation and those who class it as the same thing- ‘flutter/fib’!

I used the term 'little brother' above in jest- Atrial flutter can be equally debilitating as atrial fibrillation and also carries similar risks.

Both, atrial flutter and atrial fibrillation are abnormal, often fast, heart rhythm disorders that have a lot in common. But from an electrophysiologist’s (a cardiologist specialising in heart rhythm disorders) perspective- there are some very important differences. And it’s important as a patient to know this, so you can receive the right treatments.

From the outside, the similarities are clear- both can cause debilitating palpitations, shortness of breath, and lightheadedness. Both can increase your risk of stroke and may warrant blood thinners. Both can be managed with rate control tablets (like bisoprolol or verapamil) or rhythm control (like electrical cardioversion).

Atrial Fibrillation originates from chaotic electrical activity in the atrium that overdrives the normal heartbeat. It’s unpredictable and changes beat-to-beat. This is what can make it challenging to treat with ablation. Especially in long-standing AF, the triggers can be all over the atrium chambers and it can be difficult to know where to treat. Alternatively, atrial flutter occurs because of a single ‘short circuit’ that overdrives the normal heartbeat. So although the electrical activity is abnormal, it is predictable. The pattern on your ECG is typical and importantly, the location of the short circuitry in the atrium is fixed and singular.

Atrial flutter is a short circuit in the top right chamber of the heart. Atrial fibrillation is maintained by chaotic, unpredictable electrical activity, usually in the top left chamber of the heart. Image adapted from here.

This means the ablation procedure is more straightforward and there is a high likelihood that the ablation could be curative. In fact, many skilled electrophysiologists quote cure rates of >90% when treating atrial flutter with ablation. But (there’s always a but!) just because you’ve been cured of atrial flutter doesn’t mean you won’t get any future palpitations. Unfortunately, your risk of developing future atrial fibrillation is higher; the two arrhythmias share risk factors and 30% of patients with atrial flutter will go on to develop atrial fibrillation in the next few years.

This is why your electrophysiologist emphasises the importance of getting a copy of your ECG if you ever attend A&E.-

Atrial fibrillation can look like a noisy line on the ECG with irregular spikes. Atrial flutter can look like a 'saw-tooth' pattern due to the cyclical short circuit that consistently drives the heart beat.Image adapted from here.

Your symptoms and the A&E doctors' treatments could be exactly the same, the only way to know whether you had an episode of atrial fibrillation or atrial flutter, is if you can show them the ECG.

Especially if you’ve already had an ablation treatment for either arrhythmia. Have your symptoms come back because you’re having a recurrence of the original arrhythmia or is this a new arrhythmia you’ve developed? Having had one arrhythmia puts you at higher risk of developing the other, so this is not an uncommon situation! This is one problem that the AFFU-AW study is exploring; whether putting the power of ECG diagnostics in the hands of the patient improves the time to detection of recurrence and importantly, if it can help to identify the cause of the symptoms.

Pathway of the AFFU-AW study- currently recruiting at St Bartholomew's Hospital.

Just to complicate matters further, a singular short circuit can occur in different regions of the heart to the area where atrial flutter occurs. This is called ‘atrial tachycardia’ and can be quite hard to differentiate from atrial fibrillation or atrial flutter. It is quite rare in patients who have a structurally normal heart or have never had an ablation but in the post-ablation setting it is important to differentiate atrial fibrillation recurrence vs atrial flutter vs atrial tachycardia as the repeat ablation procedure strategies will be different. Thank you to all the patients participating in the AFFU-AW study and helping us explore the diagnostic value of wearable ECG devices!

So to summarise-

Atrial flutter differs in electrical origin from atrial fibrillation but can cause similar symptoms and complications.
Atrial flutter is a singular, fixed electrical short circuit, so treating it is more straightforward and often curative.
Whether it’s your first time having palpitations or if you’ve had ablations in the past, always take a picture of your ECG in A&E so your electrophysiologist can review it to give you personalised treatment.