Wide QRS complex tachycardia. Rapid method of prognostic evaluation

A wide QRS complex tachycardia suggests a ventricular tachycardia (VT); but supraventricular tachycardia (SVT) is also possible. Some authors reported on the electrocardiographic signs for the differential diagnosis of VT and SVT with aberrancy. Frequently these signs are debatable and the diagnosis is uncertain. The purpose of the study was to evaluate the interest of a non-invasive study by transesophageal route for the evaluation of the nature of a wide QRS complex tachycardia in which a reliable ECG algorithm does not permit to distinguish VT from SVT with aberrancy.

Esophageal electrophysiologic study (EPS) was performed in 53 patients, aged from 16 to 85 years without bundle branch block (BBB) in sinus rhythm, but with wide-QRS tachycardia. The protocol consisted of atrial pacing at progressively higher rates and then programmed stimulation with one and two extrastimuli in control state and after isoproterenol infusion. Intracardiac EPS was performed in 49 of them.

(1) Study was negative in nine patients; intracardiac EPS remained negative in four of them, induced a VT in five; (2) clinical tachycardia was induced in 44 patients: (a) in 29 of them, atrial pacing induced a BBB similar to aberrancy noted in tachycardia and the diagnosis of SVT with aberrancy was made; (b) in 15 patients, QRS complex remained narrow during atrial pacing; the diagnosis of VT was made in presence of AV dissociation and confirmed by intracardiac study. VT was induced by atrial or ventricular stimulation or was spontaneous during isoproterenol infusion. VT mechanism were bundle branch reentry [Am. J. Cardiol. 65 (1990) 322], verapamilsensitive VT [Am. J. Cardiol. 65 (1990) 322], catecholamine-sensitive VT [J. Cardiovasc. Electrophysiol. 7 (1996) 2]. Two patients had tachycardias of both natures either supraventricular or ventricular.

Esophageal EPS was a safe, rapid and economic means to evaluate the mechanism of wide QRS tachycardia in 84% of patients; atrial pacing at progressively higher rates is very simple to reproduce the aberrancy of similar morphology in those patients who had wide-QRS tachycardia related to a SVT with aberrancy. If atrial pacing did not exactly reproduce the aberrancy in tachycardia, a VT should be suspected.