Atrial flutter and post-tachycardia syncope

ECG: This extended lead II recording allows highlighting a number of elements: 1) initially, there is a probable atrial flutter (sawtooth pattern) with variable conduction and left bundle branch block; 2) the atrial flutter is reduced with the presence of a post-tachycardia sinus pause of 5 seconds; 3) presence of premature atrial extrasystoles with P-on-T pattern; 4) new onset of the atrial arrhythmia;

Comments: in this patient, two main hypotheses could initially be evoked to explain the occurrence of sudden syncope: 1) a paroxysmal complete atrioventricular block suggested by the presence of the left bundle branch block; 2) a common ventricular rhythm disorder in patients with ischemic cardiomyopathy. The recorded tracing reveals a third mechanism: a post-tachycardia sinus pause. This type of tracing therefore corresponds to a variant of atrial disease combining atrial fibrillation/flutter episodes and significant pause occurring only at the time of the end of the arrhythmia. This patient underwent a common flutter ablation, a relatively standardized procedure with a success rate exceeding 90%, which eliminated the syncopal episodes.

Take-home message: The combination of atrial flutter and post-tachycardia sinus pause is a particular form of atrial disease.