title: A prospective placebo controlled randomized study of caffeine in patients with supraventricular tachycardia undergoing electrophysiologic testing.
abstract: BACKGROUND
  Patients with cardiac arrhythmias are generally instructed to avoid caffeine intake. A comprehensive evaluation of the electrophysiological effects of caffeine on atrial and ventricular tissues in humans has not previously been performed.
  
  
  RESULTS
  Eighty patients (31 men, mean age 49 ± 14 years) with symptomatic supraventricular tachycardia (SVT) undergoing an electrophysiologic study (EPS) prior to catheter ablation were randomized to receive oral caffeine or placebo. Caffeine at a dosage of 5 mg/kg (moderate intake) or placebo tablets were administered orally at a mean time of 57 ± 13 minutes prior to the EPS. The median (IQR) caffeine level in patients receiving caffeine was 7.4 μg/mL (4.7-8.7), as compared with 0.15 (0.00-0.61) in patients receiving placebo, P < 0.0001. Caffeine was associated with a significant increase in resting systolic and diastolic blood pressures as compared with placebo, while the resting heart rate was not significantly different between both groups. Caffeine was not associated with significant effects on the effective refractory period of the atrium or ventricle, as well as on AV node conduction. SVT was induced in all but 3 patients; there was no significant difference between groups receiving placebo or caffeine on SVT inducibility or the cycle length of induced tachycardias.
  
  
  CONCLUSIONS
  Caffeine, at moderate intake, was associated with significant increases in systolic and diastolic blood pressures, but had no evidence of a significant effect on cardiac conduction and refractoriness. Furthermore, no effect of caffeine on SVT induction or more rapid rates of induced tachycardias was found.
authors: Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors: Robert
authors: R
authors: Lemery
authors: Amanda
authors: A
authors: Pecarskie
authors: Jordan
authors: J
authors: Bernick
authors: Kathryn
authors: K
authors: Williams
authors: George A
authors: GA
authors: Wells
mesh_terms: D000200:Action Potentials; D000284:Administration, Oral; D000318:Adrenergic beta-Agonists; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D002110:Caffeine / Q000008:administration & dosage* / Q000009:adverse effects; D002304:Cardiac Pacing, Artificial; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects* / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009864:Ontario; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012032:Refractory Period, Electrophysiological; D018570:Risk Assessment; D013617:Tachycardia, Supraventricular / Q000175:diagnosis / Q000503:physiopathology*; D013997:Time Factors
chemical_list: D000318:Adrenergic beta-Agonists; D002110:Caffeine
keywords: arrhythmias; atrial fibrillation; caffeine; electrophysiology testing; supraventricular tachycardia