Wide-QRS-complex tachycardia with a negative concordance pattern in the precordial leads: Are the ECG criteria always reliable?

We present a case of wide-complex tachycardia with negative concordance in the precordial leads and a qR pattern in V6, in a 42-year-old man with risk factors for coronary artery disease, in whom the electrocardiogram criteria were apparently fallible. This case highlights the key contribution of the electrophysiological study in rendering correct diagnosis.