The management of arrhythmic sincope.

Arrhythmic syncope explains 5% to 20% of the causes of syncope and its incidence increases with age. In patients with arrhythmic syncope, a poor prognosis can be expected if syncope is misdiagnosed, particularly when arrhythmias occur in a patient with advanced heart disease. Arrhythmic causes are due either to bradycardia (diagnosed by surface electrocardiography, 24-hour Holter monitoring and electrophysiologic study in patients with bundle-branch block) or to supraventricular or ventricular tachycardia (diagnosed by electrophysiologic study and/or long-term event recording). Arrhythmic syncope can be easily prevented with antiarrhythmic drugs or, more frequently, with non-medical treatments such as radiofrequency ablation of tachycardia, and pacemaker or defibrillator implantation.