Wide complex tachycardia: misdiagnosis and outcome after emergent therapy.

The extent and consequence of misdiagnosis of wide complex tachycardia (QRS, 120 ms or more; heart rate, 100 or more beats/min) presenting emergently were assessed. Forty-six consecutive episodes of wide complex tachycardia were reviewed and their tachycardia mechanisms subsequently established. All 8 episodes of supraventricular tachycardia with aberrant conduction were correctly diagnosed, whereas 15 of 38 episodes of ventricular tachycardia (39%) were misdiagnosed as supraventricular tachycardia at the time initial therapy was given. Ventriculoatrial dissociation was evident in 11 (73%) of the electrocardiograms of misdiagnosed ventricular tachycardia. Patients with misdiagnosed episodes had poorer outcomes than those with episodes correctly diagnosed (p = 0.0003). Verapamil was administered to patients in 13 of the 15 episodes of misdiagnosed ventricular tachycardia; hemodynamic deterioration occurred in all 13 episodes. Wide complex tachycardia is often incorrectly diagnosed as supraventricular tachycardia when, in fact, the 12-lead electrocardiogram strongly suggests ventricular tachycardia. Verapamil is commonly administered in these circumstances and is frequently associated with a poor outcome.