Clinical spectrum of fascicular tachycardia

AIMS: Ventricular tachycardia spreading from the anterior or posterior division of the left bundle branch is generally called fascicular tachycardia (FT). We will present our experience with FT, a type of ventricular tachycardia not necessarily implying the absence of heart disease and/or sensitivity to selective antiarrhythmic drugs, but only particular routes of left ventricular depolarization. METHODS: Since 1981 we have had the opportunity to study 10 cases of FT (nine men and one woman; aged 28-77 years, mean ± SD 55 ± 18.6 years) by means of echocardiography, coronary angiography (seven cases), endomyocardial biopsy (five cases), signal-averaged electrocardiogram (SAECG, nine patients), electrophysiological and electropharmacological evaluation. RESULTS: Seven patients had paroxystic, extrastimulus inducible FT that was sensitive to verapamil given intravenously (group A); three patients, on the other hand, showed repetitive or incessant FT, not modifiable by stimulation techniques and sensitive to class 1 antiarrhythmic drugs (group B). Patients presented histologic substrates ranging from the absence of heart disease to previous myocardial infarction or myocarditis. FT spontaneously disappeared within 2 years in group B, while frequently persisted in the long term in group A. CONCLUSIONS: FT is not a homogeneous group of ventricular tachycardia, as patients may differ according to clinical presentation, mechanisms that are involved in the genesis of the arrhythmia and natural history; the histologic substrate is highly variable, ranging from the total absence of heart disease to severe forms of myocardial involvement.