The complete syndrome is characterized by episodes of fast polymorphic VT (picture 2) in patients with an electrocardiogram showing a pattern of right bundle branch block and ST segment elevation in leads V1 to V3 (picture 1,3). The manifestations of the syndrome are caused by episodes of polymorphic ventricular tachycardia-ventricular fibrillation. When the episodes terminate spontaneously the patient develops syncopal attacks. When the episodes are sustained, full blown cardiac arrest and eventually sudden death occur. Thus, these manifestations can range widely: at the one end of the spectrum we have asymptomatic individuals and at the other end those who die suddenly. As it is seen in other clinical-electrocardiographic syndromes, there are other different presentations of the disease.

There exist asymptomatic individuals in whom the typical electrocardiogram is detected during routine examination. This electrocardiogram cannot be distinguished from that of symptomatic patients. In other patients, the characteristic electrocardiogram is recorded during screening after the sudden death of a family member with the disease. On the other hand, there is the group of symptomatic patients who have been diagnosed as suffering syncopal episodes of unknown cause or vaso-vagal origin, or have a diagnosis of idiopathic ventricular fibrillation. Some of these patients are diagnosed at follow-up, when the electrocardiogram changes spontaneously from normal to the typical pattern of the syndrome (picture 5). This is also the case for those individuals in whom the disease is unmasked by the administration of an antiarrhythmic drug given for other arrhythmias, for instance atrial fibrillation.

It really does not make a difference, this electrocardiogram, with or without symptoms, appearing spontaneously or after the administration of medications, is a marker of sudden death: Up to 40% of the individuals will develop a new or a first episode of polymorphic ventricular tachycardia or sudden death during the next 2-3 year follow-up. The only excepcion seem to be carriers who are asymptomatic and in whom the electrocardiogram is only found after administration of drugs.