[Malignant vasovagal syncope: its diagnosis and therapeutic trial based on the orthostatism test (the tilt-table test)].

Seventy consecutive patients with recurrent unexplained syncope were evaluated by use of an up-right tilt-table test for 45 minutes (with or without an infusion of isoproterenol) in an attempt to reproduce symptoms. There were 42 males and 28 females with a mean age of 49 +/- 20 years (range 7-86), and with a mean symptoms duration of 35.2 +/- 16 months. All the patients underwent clinical examination which includes cardiological and neurological evaluation. Some tilt positive patients received therapy with either transdermal scopolamine, metoprolol or clonidine, the efficacy of which was evaluated by another tilt-table test. Syncope occurred in sixteen patients (22.9%), during the baseline tilt associated with hypotension (2 patients), bradycardia-asystolia (3 patients), or both (11 patients). In 11 patients with normal baseline tilt test, isoproterenol infusion was used appearing 4 new cases of abnormal response. Some patients who had positive test results, eventually became tilt-table negative by therapy (5 out of 8 patients treated with scopolamine, 5 out of 6 patients with metoprolol, and 3 out of 5 patients with clonidine). Time before syncope during tilt-test was increased with therapy, being of 45 min in normalized cases, and increasing from 11.9 +/- 16 basal to 34.4 +/- 17 min with scopolamine (p < 0.05), to 40 +/- 12 min with metoprolol (p < 0.05) and to 33.7 +/- 16.7 min with clonidine (p = NS). We conclude that upright tilt-table alone or combined with isoproterenol infusion is an useful test in the diagnosis of vasovagal syncope and in the evaluation of therapy.