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A prospective placebo controlled randomized study of caffeine in patients with supraventricular tachycardia undergoing electrophysiologic testing.

Journal of cardiovascular electrophysiology (2014-08-02)
Robert Lemery, Amanda Pecarskie, Jordan Bernick, Kathryn Williams, George A Wells
ABSTRACT

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. 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. 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.

MATERIALS
Product Number
Brand
Product Description

Supelco
Melting point standard 235-237°C, analytical standard
Caffeine for system suitability, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
Caffeine, SAJ special grade, ≥98.5%
Supelco
Caffeine, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Caffeine Melting Point Standard, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Caffeine, anhydrous, tested according to Ph. Eur.
Supelco
Mettler-Toledo Calibration substance ME 18872, Caffeine, analytical standard, for the calibration of the thermosystem 900, traceable to primary standards (LGC)
Supelco
Caffeine, certified reference material, TraceCERT®
USP
Caffeine melting point standard, United States Pharmacopeia (USP) Reference Standard
Sigma-Aldrich
Caffeine, BioXtra
Sigma-Aldrich
Caffeine, powder, ReagentPlus®
Sigma-Aldrich
Caffeine, meets USP testing specifications, anhydrous
Sigma-Aldrich
Caffeine, Sigma Reference Standard, vial of 250 mg
Sigma-Aldrich
Caffeine, anhydrous, 99%, FCC, FG
USP
Caffeine, United States Pharmacopeia (USP) Reference Standard
Caffeine, European Pharmacopoeia (EP) Reference Standard