We read with interest the Image in Cardiology case report by Dr Preza,1 which summarizes the use of ultrasound imaging to diagnose ventricular tachycardia in a 60-year-old woman with known ischemic heart disease who presented to the emergency room after developing a hemodynamically stable regular tachycardia with a wide QRS. While recognizing the particular appeal of this diagnostic approach, we remain concerned about reliance on this method because of the risk that hemodynamic stability in a patient with established ischemic heart disease might lead to misdiagnosis of a supraventricular origin. This misdiagnosis persists even though it is well established that >90% of wide-QRS tachycardias in patients with ischemic heart disease are ventricular2 and that hemodynamic tolerance is incapable of distinguishing between ventricular and supraventricular origin.3 In cases of ventricular tachycardia due to bundle branch reentry, the electrocardiogram morphology is normally similar to that in sinus rhythm, and therefore a normal electrocardiogram cannot exclude a ventricular origin. It would have been useful to compare the complete 12-lead electrocardiograms in tachycardia and sinus rhythm in this patient, but nonetheless the leads shown are clearly not identical in the 2 situations (higher S in DIII in sinus rhythm than in tachycardia, and changing peak AVR in DII). Atrioventricular dissociation is present in only 20% to 50% of patients and is sometimes difficult to recognize, so its absence does not aid diagnosis.4
In summary, without denying the appeal of ultrasound imaging as a method for diagnosing the origin of wide-QRS tachycardia, it is important to point out that this case was exceptional, and that an accurate diagnosis can be achieved in clinical practice based on patient history and electrocardiography. We should discard criteria such as hemodynamic tolerance that have no diagnostic value and can lead to inappropriate treatment of a regular wide-QRS tachycardia, with serious clinical and prognostic implications.