TACHYCARDIAS WITH WIDE QRS - LIMITATIONS OF ELECTROCARDIOGRAPHIC CRITERIA IN PATIENTS ON ANTIARRHYTHMIC DRUGS

The diagnosis of ventricular tachycardia is difficult, often requiring endocavitary investigation to obtain proof. Many authors have attempt ed to define criteria used to distinguish between ventricular tachycar dia and supraventricular tachycardia with wide ORS in the surface elec trocardiogram. These criteria have been determined in patients not tak ing antiarrhythmic drugs. The authors report the case of a patient tre ated with flecainide for atrial fibrillation and hospitalised because of faints and tachycardia with wide complexes. The diagnosis of ventri cular tachycardia was justified by surface electrocardiogram but was e liminated by subsequent endocavitary electrophysiological studies. The use of anti-arrhythmic drugs thus limits the applicability of electro cardiographic criteria in cases of tachycardia with wide QRS.