Branch-to-branch ventricular tachycardia due to primary non-ischemic cardiomyopathy

Patient

74-year-old patient with permanent atrial fibrillation, having undergone an ablation of the atrioventricular node and implantation of a triple-chamber pacemaker (right ventricular pacing lead and left ventricular pacing lead); hospitalization for syncopal episode;

Trace

This tracing shows a monomorphic, regular tachycardia of 155 bpm with a pattern of left bundle branch block; atrial activity is difficult to identify; clinical history indicates that this patient had undergone an ablation of the bundle of His and thus presents a complete anterograde atrioventricular block; the only possible diagnosis in the presence of a tachycardia with spontaneous QRS complexes (no ventricular pacing) is therefore ventricular tachycardia; clinical history can sometimes influence the interpretation of a tracing (a history of infarction suggests ventricular tachycardia but does not guarantee its diagnosis) but can sometimes allow a diagnosis of certainty (as in this case when there is a complete atrioventricular block); probable branch-to-branch reentry tachycardia;

Trace

ECG after termination of the tachycardia, showing low-voltage atrial fibrillation, biventricular pacing (narrow QRS, negative in lead I and positive in V1); presence of a polymorphic ventricular triplet attesting to the arrhythmogenic setting;

Exergue

Branch-to-branch reentry occurs preferentially in heart failure patients with a frequent tachycardia pattern of left bundle branch block.