Wide-QRS-Complex Tachycardia with a Negative Concordance Pattern in the Precordial Leads: is a supraventricular origin possible?

The initial electrocardiographic evaluation of every tachyarrhythmia should begin by addressing the question of whether the qrs complex is wide or narrow. the most important cause of wide complex tachycardia (wct) is ventricular tachycardia (vt). however, supraventricular tachycardia (svt) can also manifest with a wide qrs complex. the ability to differentiate between svt with a wide qrs due to aberrancy or preexcitation and vt often presents a diagnostic challenge. the identification of whether wct has a ventricular or supraventricular origin is critical because the treatment for each is different, and improper therapy may have potentially lethal consequences. when all qrs complexes in the precordial leads are either upright or negative (positive or negative concordance, respectively), vt is strongly suggested. negative concordance is virtually diagnostic of vt generated from the anteroapical left ventricle. we report an extremely rare case of svt presenting with a wct and negative concordance.