REPRODUCIBILITY OF THE ADENOSINE-5'-TRIPHOSPHATE TEST IN VASOVAGAL SYNDROME

Introduction: Adenosine-5'-triphosphate (ATP) provokes negative chrono tropic and dromotropic vagal effects. In vasovagal syndrome, ATP test (20-mg IV bolus infusion) represents a promising technique for identif ying patients at risk of severe cardioinhibitory response of vagal ori gin. The electrocardiographic and related symptom reproducibility of t his descriptive test must be assessed. Methods and Results: In order t o achieve this objective, ATP tests were performed twice in 80 patient s (44 men, 36 women; mean age 72.3 +/- 12.2 years) by using the recent ly published test procedure and criteria of positivity, The second tes t was repeated shortly after the initial test (mean: 7 days) in 43 pat ients 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 (less than or equal to 10 sec) or no pause in 49 p atients (61%). The electrocardiographic outcome was reproduced during the second ATP test in 36 patients (84%) of the short-term group and i n 29 patients (78%) of the long-term group, Similarly, symptoms were r eproduced in 38 patients (88%) of the short-term group and 29 patients (78%) of the long-term group, reflecting the severity of the electroc ardiographic outcome. Conclusion: The negative chronotropic and dromot ropic vagal effect of ATP can be reproduced short term and long term i n 84% and 78% of patients, respectively, Associated symptoms were rela ted to the severity of the electrocardiographic outcome.