Reproducibility of the adenosine-5'-triphosphate test in vasovagal syndrome

Adenosine-5'-triphosphate (ATP) provokes negative chronotropic and dromotropic vagal effects. In vasovagal syndrome, ATP test (20-mg i.v. bolus infusion) represents a promising technique for identifying patients at risk of severe cardioinhibitory response of vagal origin. The electrocardiographic and related symptom reproducibility of this descriptive test must be assessed.

In order to achieve this objective, ATP tests were performed twice in 80 patients (44 men, 36 women; mean age 72.3+/-12.2 years) by using the recently published test procedure and criteria of positivity. The second test was repeated shortly after the initial test (mean: 7 days) in 43 patients and long-term (mean: 3.7 years) in 37 patients. The initial ATP test provoked a cardiac pause > 10 seconds in 31 patients (39%) and a short cardiac pause (< or =10 sec) or no pause in 49 patients (61%). The electrocardiographic outcome was reproduced during the second ATP test in 36 patients (84%) of the short-term group and in 29 patients (78%) of the long-term group. Similarly, symptoms were reproduced in 38 patients (88%) of the short-term group and 29 patients (78%) of the long-term group, reflecting the severity of the electrocardiographic outcome.

The negative chronotropic and dromotropic vagal effect of ATP can be reproduced short term and long term in 84% and 78% of patients, respectively. Associated symptoms were related to the severity of the electrocardiographic outcome.