Case B16. Paroxysmal Atrial Fibrillation. St Emlyn’s ECG Library.

Case B16. Paroxysmal Atrial Fibrillation. St Emlyn's ECG Library.


The EGG was recorded from a patient who developed palpitations, and was referred by his general practitioner to the ‘open access’ ECG service.


Rhythm: In the first two sets of three leads there is no consistent recognizable atrial activity. The QRS complexes are irregular; atrial fibrillation is present. While leads VI, V2 andV3 were being recorded the rhythm changed. P waves are now clearly visible and the rhythm strip recorded at the foot of the page shows that sinus rhythm has returned. The third beatfrom the end of the rhythm strip is a premature beat with normal QRS configuration. This is preceded by a P wave of different shape to the normal sinus P waves seen in this lead- this is an atrial premature beat

Morphology: There is a pathological Q wave in lead aVL,(the Q wave in lead I is less than .04 seconds in duration andtherefore does not satisfy the criteria to be considered pathological). Q waves are present in V2 and V3. R wave progression is late in the precordial leads – no significant Rwave is seen till lead V4. These appearances are suggestive of old infarction although not very striking. There is ST segment depression in leads II, III and aVF which is also compatible with ischaemia.


Atrial fibrillation often occurs in ischaemic heart disease and the EGG supplies some supporting evidence for the presence of this. Other causes include valvular heart disease(especially when the mitral valve is affected), thyroid heart disease, cardiomyopathy and sino-atrial disease. Atrial fibrillation often occurs in self limiting episodes, particularly early in the course of the condition and on this occasion it has reverted to sinus rhythm halfway through the recording.

Cite this article as: Simon Carley, "Case B16. Paroxysmal Atrial Fibrillation. St Emlyn’s ECG Library.," in St.Emlyn's, November 18, 2018,

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