Syncope Should Not Be Taken Lightly
Abstract & Commentary
Source: Soteriades ES, et al. Incidence and prognosis of syncope. N Engl J Med 2002;347:878-885.
The authors evaluated participants enrolled in the Framingham Heart Study between 1971 and 1998 who reported syncopal events. The patients’ reports were confirmed by review of hospital and outpatient records, and the etiology of the syncopal episode was determined by two physicians utilizing all available records and test results. Patients not seeking medical care were classified as having an unknown cause of syncope if there were no features in the history, examination, or electrocardiogram indicative of a cardiac event. The authors excluded patients from analysis if the report of syncope was equivocal or if they were lost to follow-up after the episode.
Of the 7814 study participants followed for an average of 17 years, 822 reported syncope and follow-up data was available for 727. The etiology of syncope could not be determined in 31% of patients. A vasovagal etiology was diagnosed in 24%, followed by orthostatic syncope (10%), medication-related syncope (7%), seizure (7%), cardiac etiology (7%), and stroke/transient ischemic attack (2%). Miscellaneous causes of syncope (micturition, cough) accounted for 13%. The incidence of syncope was the same in men and women.
Survival analysis showed that patients with syncope of any etiology were more likely to have cardiovascular disease and had a risk of death 31% greater than matched controls who did not report syncopal episodes. Among patients with cardiac syncope, the risk of death was twice that of controls. The risk of stroke among patients with neurologic causes of syncope was three times that of controls. Patients with syncope of unknown etiology also had an increased risk of adverse events. Those diagnosed with vasovagal, orthostatic, medication-related, and miscellaneous (but identifiable) causes of syncope had no increased risk of death, stroke, or myocardial infarction compared to controls. The authors conclude that patients with syncope of cardiac, neurologic, or unknown etiologies have an increased risk of death and merit further evaluation, while "benign" etiologies of syncope are not associated with adverse events.
Commentary by David J. Karras, MD, FACEP, FAAEM
While this study does not break new ground, it is by far the largest and most convincing affirmation of the need to take syncope quite seriously. The results confirm guidelines, derived from much smaller study groups, that call for extensive evaluation of patients with syncope deemed likely to be cardiac in etiology.1,2 It strengthens the argument for intensive investigation—probably in an inpatient setting—for those likely to have syncope related to a neurologic event. Equally important, this study identifies syncope of unknown etiology as a marker of adverse outcome. While the good prognosis of patients with "benign" causes of syncope is reassuring, it emphasizes the need to perform a careful history and examination to distinguish benign syncope from idiopathic syncope.
The authors performed a number of secondary analyses that effectively excluded a number of potentially confounding factors. Unfortunately for the algorithmically inclined physician, they did not attempt to develop management guidelines.
Dr. Karras, Associate Professor of Emergency Medicine, Department of Emergency Medicine Temple University School of Medicine, Director of Emergency Medicine Research, Temple University Hospital, Philadelphia, PA, is on the Editorial Board of Emergency Medicine Alert.
References
1. Martin TP, et al. Risk stratification of patients with syncope. Ann Emerg Med 1997;29:459-466.
2. Linzer M. Diagnosing syncope. Part 1: Value of history, physical examination, and electrocardiography. Clinical Efficacy Assessment Project of the American College of Physicians. Ann Intern Med 1997;126:989-996.
The authors of this study in the New England Journal of Medicine evaluated participants enrolled in the Framingham Heart Study between 1971 and 1998 who reported syncopal events.
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