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Patient
83-year-old man; hospitalized for syncope
Trace
Atrial fibrillation: very rapid atrial activity, polymorphic, disorganized with baseline tremor; ‘slow AF’ corresponding to conducted AF (irregular narrow ventricles) but with altered atrioventricular conduction (very slow ventricles); the third complex probably corresponds to a junctional escape rhythm (narrow QRS with a slightly different pattern compared to the conducted QRS complexes);
Exergue
The diagnosis of atrial fibrillation should be focused on the evidencing of an irregular, disorganized and very rapid atrial activity. The presence of a rapid and irregular ventricular rate is common but is not a prerequisite for diagnosis. Indeed, as in this patient, the ventricular rate may be slow and relatively regular in the presence of an atrioventricular conduction disorder.
This patient has atrial fibrillation with slow atrioventricular conduction. During an AF episode with preserved atrioventricular conduction, ventricular rhythm is generally irregular, rapid and greater than 100 bpm, although remains much lower than that of the atria.