DIAGNOSING SYNCOPE .1. VALUE OF HISTORY, PHYSICAL-EXAMINATION, AND ELECTROCARDIOGRAPHY

Purpose: To review the literature on diagnostic testing in syncope and provide recommendations for a comprehensive, cost-effective approach to establishing its cause. Data Sources: Studies were identified throu gh a MEDLINE search (1980 to present) and a manual review of bibliogra phies of identified articles. Study Selection: Papers were eligible if they addressed diagnostic testing in syncope or near syncope and repo rted results for at least 10 patients. Data Extraction: The usefulness of tests was assessed by calculating diagnostic yield: the number of patients with diagnostically positive test results divided by the numb er of patients tested or, in the case of monitoring studies, the sum o f true-positive and true-negative test results divided by the number o f patients tested. Data Synthesis: Despite the absence of a diagnostic gold standard and the paucity of data from randomized trials, several points emerge. First, history, physical examination, and electrocardi ography are the core of the syncope workup (combined diagnostic yield, 50%). Second, neurologic testing is rarely helpful unless additional neurologic signs or symptoms are present (diagnostic yield of electroe ncephalography, computed tomography, and Doppler ultrasonography, 2% t o 6%). Third, patients in whom heart disease is known or suspected or those with exertional syncope are at higher risk for adverse outcomes and should have cardiac testing, including echocardiography, stress te sting, Holter monitoring, or intracardiac electrophysiologic studies, alone or in combination (diagnostic yields, 5% to 35%). Fourth, syncop e in the elderly often results from polypharmacy and abnormal physiolo gic responses to daily events. Fifth, long-term loop electrocardiograp hy (diagnostic yield, 25% to 35%) and tilt testing (diagnostic yield l ess than or equal to 60%) are most useful in patients with recurrent s yncope in whom heart disease is not suspected. Sixth, psychiatric eval uation can detect mental disorders associated with syncope in up to 25 % of cases. Seventh, hospitalization may be indicated for patients at high risk for cardiac syncope (those with an abnormal electrocardiogra m, organic heart disease, chest pain, history of arrhythmia, age >70 y ears) or with acute neurologic signs. Conclusions: Many tests for sync ope have a low diagnostic yield. A careful history, physical examinati on, and electrocardiography will provide a diagnosis or determine whet her diagnostic testing is necessary in most patients.