Is a pacemaker indicated for vasovagal patients with severe cardioinhibitory reflex as identified by the ATP test? A preliminary randomized trial.

Background: A previous observational study suggested that, in syncopal elderly patients with vasovagal syndrome, a test using adenosine-5'-triphosphate (intravenous ATP 20 mg. 2 ml-1) could identify a subgroup of patients at high risk of severe cardioinhibitory response and guide the therapeutic strategy. To test one aspect of these results prospectively, we designed a small study focusing only on vasovagal patients with abnormal response to ATP testing.

Can adenosine 5'-triphosphate be used to select treatment in severe vasovagal syndrome?

Background: Selection of treatment in vasovagal syndrome should be guided by the mechanism of symptoms. This study determined whether a simple drug test may assess one mechanism.

Methods And Results: To identify patients at risk of severe cardioinhibitory response of vagal origin, we infused 20 mg ATP into 316 patients hospitalized for recurrent syncope (n=195) or presyncope (n=121) of unknown origin and into normal subjects (n=51).