Abstract 15629: A Prospective Placebo Controlled Randomized Study of Caffeine in Patients With Supraventricular Tachycardia Undergoing Electrophysiological Testing. I. Effects on Cardiac Conduction and Refractoriness
Background: A comprehensive evaluation of the electrophysiological effects of caffeine on atrial and ventricular tissues in humans has not previously been performed.
Objective: To determine atrial, ventricular and nodal refractoriness and conduction times in patients with supraventricular tachycardia (SVT) undergoing an electrophysiologic study (EPS) prior to catheter ablation.
Methods: Eighty patients (31 men, mean age 49 +/- 14 years) with symptomatic SVT were randomized to receive oral caffeine or placebo prior to their EPS. Caffeine tablets 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 EPS. Catheters were introduced under fluoroscopic guidance to the RA, RV, AV node and coronary sinus (CS). Programmed electrical stimulation was performed to determine refractoriness and conduction times of atrial, ventricular and nodal tissues.
Results: Caffeine was associated with a significant increase in resting blood pressure (mean systolic of 148 +/-23 mmHg in patients receiving caffeine, as compared with 133 +/- 79 mmHg in patients receiving placebo, p < 0.007, and mean diastolic of 86 +/- 12 mmHg as compared with 77 +/- 11 mmHg, p < 0.02). The resting heart rate was not significantly different between both groups, mean of 75 +/- 14 bpm. While pacing the RA, CS and RV at 500 msec., caffeine was not associated with significant effects on the effective refractory period of respectfully the RA (mean 215 +/- 35 msec.), LA (mean 233 +/- 31 msec.) and RV (233 +/- 30 msec.). The AV node Wenckebach was not significantly different between both groups (mean 363 +/- 69 msec.).
Conclusions: We provide the first report of a comprehensive evaluation of the electrophysiological effects of caffeine in human cardiac tissues. Caffeine, at moderate intake, was associated with a significant increase in systolic and diastolic blood pressure, but had no evidence of an effect on cardiac conduction and refractoriness.
- © 2013 by American Heart Association, Inc.