Lidocaine-sensitive atrial tachycardia - Lidocaine-sensitive, rate-related, repetitive atrial tachycardia: A new arrhythmogenic syndrome

OBJECTIVES The goal of this study was to report a variety of atrial tachyca rdia that might be caused by an unusual electrophysiologic substrate. BACKGROUND The mechanism of atrial tachycardias is attributed to re-entry, abnormal automaticity or triggered activity, based on their electropharmaco logical responses. A rate-related and lidocaine-sensitive atrial tachycardi a has not been reported. METHODS Eight patients (3 women and 5 men, aged 14 to 60 years) with repeti tive, uniform atrial tachycardias were studied. In six patients the arrhyth mia had been refractory to at least three antiarrhythmic agents (class 1A a nd C sodium channel blockers, amiodarone, beta-adrenergic blocking agents, verapamil, digoxin). Conventional electrocardiograms, Holter recordings and B mode echocardiograms were performed in each patient. Intravenous lidocai ne and verapamil were tested in the eight patients. Six patients underwent an electrophysiologic study. RESULTS The baseline electrocardiogram showed nearly incessant runs of atri al tachycardia in all patients. The mean atrial ectopic cycle length ranged from 376 to 502 ms. In seven patients a progressive prolongation of the cy cle length from the beginning to the end of the salves was documented. The arrhythmia. was suppressed by increments of sinus node rate and by atrial p acing at cycle lengths longer than that of the atrial tachycardia. In all p atients the arrhythmia was abolished by intravenous lidocaine, whereas intr avenous verapamil was ineffective. Four symptomatic patients were successfu lly treated with radiofrequency ablation of the ectopic focus, and two pati ents were treated with oral mexiletine. CONCLUSIONS The peculiar electropharmacological responses of this arrhythmi a suggest an uncommon underlying mechanism that remains to be elucidated. ( C) 2000 by the American College of Cardiology.