Recurrent syncope--a diagnostic challenge

Several disorders resemble syncope. According to the European Society of Cardiology guidelines, certain key questions should be addressed during the initial evaluation of a patient presenting syncope. The physician should be alert to important clinical features that suggest the diagnosis and the evaluation strategy. However, syncope remains a diagnostic challenge. The authors report a case of a 60-year-old man admitted to the Emergency Department (ED) complaining of recurrent syncopal attacks that had begun one month before. He had daily transient, self-limited loss of consciousness lasting for seconds or even a few minutes, followed by prompt recovery. The attacks occurred mainly after exercise or urination. Prodromal symptoms were sweating and a sensation of imminent death. He learned to recognize these symptoms, reporting that he could control the duration of the attack by sitting down and voluntarily hyperventilating. He reported no prior pain, palpitations, tongue-biting or urinary incontinence. The episodes were witnessed and no abnormal movements were reported. The patient had been healthy until two months before, when he was diagnosed with diabetes mellitus by his general practitioner after routine analyses. Glycemia was controlled with diet and subcutaneous Actrapid insulin. No history of cardiac, cardiopulmonary, neurological or psychiatric disease was found and he was taking no other medication. On admission to the Emergency Department he was asymptomatic. Clinical examination was normal. The ECG showed sinus rhythm, heart rate of 70 bpm, and left bundle branch block; (LBBB). The chest X-ray was normal. As some medical features suggested a cardiac etiology (post-exercise, LBBB) and others indicated a neurally-mediated reflex syndrome or even situational syncope (after urination), a diagnostic strategy to exclude cardiac cause was adopted, including echocardiogram, and 24-hour ECG monitoring and stress test. The echocardiogram was normal. During Holter monitoring, he reported a syncopal event, in supine position, immediately after urination, and a 50-second period of cardiac arrest with persistent P waves--P-wave asystole--was recorded. Cardiac bradyarrhythmia was thus established as the cause of the syncope and a permanent pacemaker was implanted, with no recurrence of symptoms. This example of an unusually long-lasting cardiac arrest with spontaneous recovery illustrates the non-specific nature of clinical features and how difficult it is to diagnose syncope in an Emergency Department setting. The authors briefly review the topic according to recent guidelines.