[An analysis of the responses to the tilt-table test depending on the clinical characteristics of the syncopal episodes in patients without apparent cardiopathy].

Seventy-six consecutive patients were evaluated to assess whether the response to head-up tilt test was related to the type of clinical presentation in patients with syncope of unknown origin and free from heart disease. The syncopal attacks were clinically characterized in a prospective fashion before the tilt test. In 44 patients (group I) syncope had been preceded by autonomic symptoms or was associated with recent or static sustained orthostatism. In 32 patients (group II), syncope had been sudden, without prodromal or autonomic symptoms. Mean age was 49 +/- 17 years in group I patients and 47 +/- 17 years in group II patients (NS). The degree of tilt was 75 degrees. During 30 min no drugs were administered, and then isoproterenol was infused for an additional 20 min (1-5 micrograms/min until a maximal heart rate of 140 bpm was achieved). Tilt test was considered as positive when the patient developed syncope or presyncope with hypotension. Tilt test was positive in 33 patients from group I (75%) and 12 from group II (37.5%)(p = 0.001). The positive response developed within the 30 initial min of the test (without isoproterenol infusion) in 19 of 33 patients from group I (57%) and in 3 of 12 patients from group II (25%) (p = 0.053). It is concluded that the response to tilt test is related to the clinical features of syncopal attacks.