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A prospective placebo controlled randomized study of caffeine in patients with supraventricular tachycardia
Robert Lemery1, Amanda Pecarskie, Jordan Bernick
1Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
Insights
Moderate caffeine intake increases blood pressure but does not affect cardiac electrophysiology or supraventricular tachycardia (SVT) induction in patients undergoing electrophysiologic studies.
Area of Science:
- Cardiology
- Electrophysiology
- Pharmacology
Background:
- Patients with cardiac arrhythmias are often advised to avoid caffeine.
- Previous research has not comprehensively evaluated caffeine's electrophysiological effects on human atrial and ventricular tissues.
Purpose of the Study:
- To investigate the electrophysiological effects of moderate caffeine intake on cardiac tissues in humans.
- To assess caffeine's impact on supraventricular tachycardia (SVT) induction and characteristics.
Main Methods:
- Eighty patients with symptomatic SVT undergoing electrophysiologic study (EPS) were randomized to receive oral caffeine (5 mg/kg) or placebo.
- Caffeine levels were measured, and electrophysiological parameters including refractoriness and conduction were assessed.
- SVT inducibility and tachycardia cycle length were evaluated post-administration.
Main Results:
- Caffeine intake significantly increased resting systolic and diastolic blood pressures compared to placebo.
- No significant differences were observed in resting heart rate, atrial or ventricular refractoriness, or AV node conduction.
- Caffeine did not significantly affect SVT inducibility or the cycle length of induced tachycardias.
Conclusions:
- Moderate caffeine intake elevates blood pressure without significantly impacting cardiac electrophysiological properties.
- Caffeine does not appear to influence the induction or speed of supraventricular tachycardias.
Introduction:
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.
Methods And 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.
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