Cardiogenic syncope. Seizure versus syncope.

Our recommendations for the evaluation of the patient with suspected cardiogenic syncope are as follows: An initial thorough history and physical examination of the patient will suggest the diagnosis of cardiogenic syncope in at least 50 per cent of patients. A sudden occurrence of syncope, or "drop attack", is most suggestive of an arrhythmic cause for syncope. If there is no evidence of neurologic, metabolic, or obvious cardiac (for example, aortic stenosis) cause for syncope, a 24-hour ambulatory ECG should be performed. If the patient has had repeated syncopal episodes or if the patient has had seizures that are difficult to control with anticonvulsant therapy, ambulatory ECG monitoring may reveal an arrhythmia in these preselected patients. If the initial 24-hour ambulatory ECG is negative and if the patient has had multiple episodes of syncope, multiple days of recording will be necessary before typical symptoms occur that correlate with arrhythmias. Seventy-two hours of ambulatory ECG monitoring should be sufficient in most instances to establish an arrhythmic cause for syncope. Echocardiography and exercise stress testing are not routinely indicated in the evaluation of syncope unless the clinical history and examination suggest valvular or coronary disease. Rarely, an atrial myxoma will be visualized by echocardiography that is not apparent clinically. Those patients who still have unexplained recurrent syncopal episodes, despite all noninvasive studies, can benefit from invasive electrophysiologic studies, although the expected yield from electrophysiologic testing is low.