Bromocriptine test in the evaluation of patients with syncope of unknown aetiology - A case-control study

The aim of the present study was to evaluate, through a case-control study, the specificity of the upright tilt test with bromocriptine as a marker of neurally mediated syncope of unknown aetiology. We have compared upright t ilt test with bromocriptine (2.5 mg p.o.) in patients with syncope of unkno wn aetiology and controls. A total of 23 patients and controls matched by a ge and sex had upright tilt test with bromocriptine. The upright tilt test procedure consisted of 10 min in supine position, 10 min of 60 degrees head -up tilt and a further 10 min with the subject supine; this procedure was p erformed in baseline condition and 60, 120, 180 and 240 min after the admin istration of bromocriptine. The protocol end points were the development of syncope or presyncope in association with hypotension with or without brad ycardia. A positive response to bromocriptine test was found in 78% (95% CI , 61% to 95%) of patients and in 13% (95% CI, 0% to 26%) of controls (P < 0 .001). No significant differences were detectable among patients and contro ls showing a positive response to the test. Bromocriptine test seems to be a useful alternative tool for the diagnosis of neuromediated syncope also s uggesting that dopaminergic supersensitivity may, at various and to varying degrees, play a role in the pathogenesis of syncopal episodes.