[Cardiac syncope : diagnosis and therapy]

The second most frequent category of syncope is cardiac syncope. In contrast to syncope of noncardiac causes, the 1-year mortality of patients presenting with cardiac syncope without treatment is as high as 33%. Therefore, immediate diagnosis and treatment are necessary. Bradyarrhythmias or tachyarrhythmias are the most common causes of cardiac syncope. In many cases, an initial evaluation including history, physical examination, and electrocardiogram identifies the cause of syncope, so that specific treatment can be initiated immediately. In the remainder of cases, implantable loop recorders are useful to identify arrhythmias, while the presence or absence of structural cardiac disease is diagnosed by echocardiography. Syncope due to arrhythmias is typically treated with implantation of a pacemaker or an implantable cardioverter-defibrillator; treatment of syncope of other cardiac causes requires therapy of the underlying heart disease.