Assoc Prof Harry Mond
May 13, 2025
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A 47-year old concert pianist presented with atypical migraine. The ECG was reported as atrial fibrillation with a controlled ventricular response.
Commenced on anticoagulants.
Now on life support in intensive care following a massive haematemesis/melaena.
What do you think?
The areas on the ECG in red highlight show sinus rhythm (red arrows). The QRS complexes in the lead II rhythm strip are regular (blue arrows) and there is modest mechanical artefact from the left leg (II, III, aVF).
This is clearly sinus rhythm and the misdiagnosis led to serious complications from anticoagulant therapy.
The reporting of atrial fibrillation on the 12-lead ECG, particularly with artefact, is the most common serious misdiagnosis with ECG reporting.There is almost always a clue to the diagnosis of sinus rhythm.
If unsure:
The following tracings were all reported as atrial fibrillation (unless specified).
Regular sinus tachycardia (red arrows).
Interference most likely from left arm (leads I, III).
Think Parkinsonian tremor.
Regular sinus rhythm (red arrows).
Interference most likely right arm (leads I, II).
Again think Parkinsonian tremor.
Regular sinus rhythm (red arrows).
Interference most likely left arm (leads I, III).
Think Parkinsonian tremor.
This ECG was reported as atrial flutter.
Interference most likely left arm (leads I, III).
Think Parkinsonian tremor.
Poor quality ECGs with atrial ectopics are frequently diagnosed as atrial fibrillation.
Sinus rhythm (red arrows) with atrial ectopics (purple arrows).
The rhythm strip shows a regular ventricular rate (blue arrows) interrupted by premature atrial ectopics (purple arrows) and compensatory pauses.
Another example which highlights how easy it is to diagnose atrial fibrillation.
Sinus rhythm (red arrows) with premature atrial ectopics (purple arrows).
Interference most likely left leg (leads II, III).
Despite obvious artefact without a change in rate (red highlight), this was still called sinus rhythm(red arrows) with a short run of atrial fibrillation).
Sometimes artefact is subtle(yellow highlight) and suggests an irregular heart rate.
Yes, this was called atrial fibrillation, despite the obvious P waves (red arrows).
With miniscule P waves (red arrow), sinus rhythm can be difficult to diagnose.
In this case, despite the regular heart rate, the auto-interpretative reporting system diagnosed atrial fibrillation.
When it is atrial fibrillation, don’t doubt the diagnosis.
Patient with Parkinson’ disease.
The interference was recognised as such, and the diagnosis was sinus rhythm with an atrial run. It is clearly irregular and no P waves and thus atrial fibrillation.
Remember, everyone makes these errors.
Taking care with reporting, means you make them less than others.
Harry Mond
July 9, 2026
No tricks. Just a selection of tracings from a Holter study.Look at each one carefully, use calipers, arrows and highlight and write down your conclusions.
July 2, 2026
I came across these two tracings from the same patient during Holter reporting. Do you agree with the reported diagnoses?
June 26, 2026
I was asked to review this Holter monitor, the report of which stated: “Sinus rhythm, ventricular rate ~ 90 bpm, Wenckebach AV block”. What do you think?
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