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Abstract & Commentary
Source: Soteriades ES, et al. Incidence and prognosis of syncope. N Engl J Med. 2002;347:878-885.
Syncope is a compound word derived from 2 Greek roots: the adverb syn meaning "at once" and the verb koptein meaning "to cut." Therefore, the term refers to the actions of the Three Fates of Greek Mythology who both spun out and cut short the thread of each person’s life and consciousness. Fortunately in clinical practice syncope is a brief, sudden loss of consciousness, associated with the inability to maintain postural tone, followed by spontaneous recovery.
Although syncope is common, its epidemiology and prognosis have not been well described. Soteriades and colleagues, therefore, evaluated the incidence, causes, and prognosis of syncope among men and women taking part in the Framingham Heart Study (Kannel WB, et al. Am J Epidemiol. 1979;110:281-290).
They followed the participants, 3563 men and 4251 women, for an average of 17 years. A total of 822 (348 men and 474 women; mean age, 66 years) reported having had a syncopal episode. The incidence rate of a first report of syncope was 6.2 per 1000 person years. The incidence increased with age: there was a sharp rise at 70 years to 11.1 per 1000 person years, and at 80 years there was a further increase for men and women, respectively, to 16.9 and 19.5 per 1000 person years.
The causes identified most frequently in men and women, respectively, were: cardiac causes (13% and 7%), unknown cause (31% and 41%), TIA or stroke (4% in both), seizure (7% and 3%), vasovagal faint (20% and 22%), orthostatic hypotension (9% and 10%), medication (6% and 7%), and other causes (10% and 6%).
Seventy-eight percent of participants (570) reported only 1 syncopal episode, 23% (157) reported 1 or more. The risk of recurrence was especially high among those with cardiac syncope (multivariable-adjusted hazard ratio = 30.3).
During a mean follow-up of 8.6 years, among 2181 subjects, there were 847 deaths from all causes, 263 myocardial infarcts (MI) or deaths from coronary artery disease, and 178 fatal or nonfatal strokes. The risk of death was increased by 31% among all participants with syncope and was doubled among those with cardiac syncope, as compared to subjects without syncope. Syncope of unknown cause and neurologic syncope including TIA and seizure were associated with an increased risk of death; neurologic syncope with a three-fold risk of stroke. Vasovagal syncope was not associated with an increased risk of death, MI, or stroke.
The merits of this study are that it was population-based and, therefore, free of selection bias, and that the period of follow-up was long. The finding that cardiac syncope was associated with an increased risk of death and cardiovascular events is consistent with previous studies (Kapoor WN. Medicine. 1990;69:160-175) and current cardiologic evaluation and treatment of such patients. Likewise the finding that vasovagal syncope, including orthostatic and medication-induced faints, had a benign prognosis is not surprising and is in accord with the general clinical experience.
Neurologists will have difficulty accepting the authors’ classification of TIA and seizures as "neurologic syncope." Soteriades et al’s statement that "the increased risk of stroke in participants with neurologic syncope may be attributable to preexisting cerebrovascular disease," reflects the fact that a TIA even by another name increased the risk for stroke. Therefore, when the thread of consciousness is cut, the means, whether by a simple faint, or by a TIA, matters. —John J. Caronna
Dr. Caronna, Vice-Chairman, Department of Neurology, Cornell University Medical Center; Professor of Clinical Neurology, New York Hospital, is Associate Editor of Neurology Alert.