Background: Syncope commonly occurs in older patients, with a prevalence of 10 percent. The prevalence increases to 23 percent in patients living in nursing homes. However, little is known about the causes of syncope in this group of patients. Ungar and colleagues used a standardized protocol to determine the causes of syncope in older patients.

The Study: Patients 65 years and older who were evaluated for transient loss of consciousness were included in the two-year study. Patients were excluded if they had poor cognitive or physical function, active malignancy, or presyncope (i.e., no actual loss of consciousness).

Patients were evaluated according to a strict algorithm, beginning with a history, physical examination, and electrocardiography (ECG). After the initial evaluation, patients were determined to have an actual diagnosis, a suspected diagnosis, or an unknown diagnosis. Suspected diagnoses included cardiac, cerebrovascular, or neuromediated causes (i.e., vasovagal and situational syncope, carotid sinus syndrome, and orthostatic syncope). Patients with a suspected or unknown diagnosis received one or more of the following tests, depending on the initial assessment: 24-hour Holter monitor test, echocardiography, exercise stress test, electrophysiologic studies (cardiac work-up), tilt-table test, or carotid sinus massage (neurologic work-up).

Results: Of 231 patients with syncope, 71 were 65 to 75 years of age, and 160 were older than 75 years. A prodromic symptom (e.g., dizziness, diaphoresis, nausea, abdominal discomfort, dyspnea, chest pain, palpitations) occurred in 72.9 percent of patients. Using the protocol, initial evaluations yielded a definitive diagnosis in 40.1 percent of patients and a suspected diagnosis in 57.9 percent of patients.

The initial evaluation found a neuromediated cause of syncope in 73.6 percent of patients, a cardiac cause in 22.8 percent of patients, a neurologic cause in 3.6 percent of patients, and no diagnosed cause in 2 percent of patients. Further evaluation confirmed a cardiac cause in 43.7 percent of patients and a neuromediated cause in 83.5 percent of patients. Only one out of 113 patients with normal ECG and no structural heart disease had a cardiac cause of syncope. Neuromediated syncope accounted for two thirds of syncopal episodes overall and was the most common cause of syncope in patients 75 years and older. A cardiac cause was found in 14.7 percent of all patients, and no diagnosis could be made in 10.4 percent of patients.

Conclusion: The authors conclude that a cause of syncope could be found in many more patients than previously reported. Because of the prevalence of prodromic symptoms, their presence is not helpful in making a diagnosis. The authors conclude that the prevalence of vasodepressive causes of syncope warrants a careful review of drug therapy in older patients with syncope.