Potentially misleading manifestation of a ventricular pre-excitation

We present the case report of a 56-year-old man with an unusual manifestation of an accessory pathway. Failure to detect, or incorrect diagnosis, of this anomaly could have put the patient at high risk of sudden cardiac death. The accessory pathway described in this case report was located at the left posteroseptal area and presented initially with a broad QRS complex tachycardia. Despite being pre-excited atrial fibrillation, it could have been misinterpreted as ventricular tachycardia. Once the rhythm had changed to sinus, a Q-wave in the inferior ECG leads became apparent. This finding could have been misdiagnosed as an old myocardial infarction and treated as such, including prescription of betablockers which might, in theory, increase the risk of sudden cardiac death. The treatment of choice for the patient was radio frequency ablation of the accessory pathway.