[Tachycardia with wide QRS. Limitations of electrocardiographic criteria in patients treated with anti-arrhythmia agents].

The diagnosis of ventricular tachycardia is difficult, often requiring endocavitary investigation to obtain proof. Many authors have attempted to define criteria used to distinguish between ventricular tachycardia and supraventricular tachycardia with wide QRS in the surface electrocardiogram. These criteria have been determined in patients not taking antiarrhythmic drugs. The authors report the case of a patient treated with flecainide for atrial fibrillation and hospitalised because of faints and tachycardia with wide complexes. The diagnosis of ventricular tachycardia was justified by surface electrocardiogram but was eliminated by subsequent endocavitary electrophysiological studies. The use of anti-arrhythmic drugs thus limits the applicability of electrocardiographic criteria in cases of tachycardia with wide QRS.