The Impact of Caffeine on Brachial Endothelial Function in Healthy Subjects and in Patients With Ischemic Heart Disease

Overview

Prior work (Chris, M. et al, Clinical Science 2005; 109, 55-60) has demonstrated that drinking a cup of coffee (80-100 mg of caffeine) an hour before endothelium-dependent FMD (flow-mediated dilatation) of the brachial artery, effects endothelial function in healthy adults subjects. This effect might be attributed to caffeine, given that decaffeinated coffee (\<2 mg of caffeine) was not associated with any change in endothelial performance. In the current study we intend to further examine the impact of caffeine on brachial endothelial function among healthy subjects \& in patients with proven ischemic heart disease.

Background: Prior work (Chris, M. et al, Clinical Science 2005; 109, 55-60) has demonstrated that drinking a cup of coffee (80-100 mg of caffeine) an hour before endothelium-dependent FMD (flow-mediated dilatation) of the brachial artery, effects endothelial function in healthy adults subjects. This effect might be attributed to caffeine, given that decaffeinated coffee (\<2 mg of caffeine) was not associated with any change in endothelial performance. In the current study we intend to further examine the impact of caffeine on brachial endothelial function among healthy subjects \& in patients with proven ischemic heart disease. Aim: To evaluate the impact of 200 mg caffeine tablet intake (equivalent to 2 cups of coffee), compared to placebo on brachial endothelial function in healthy subjects \& in patients with proven ischemic heart disease. Methods: 1. Patients will be invited for two endothelial function tests 1 week apart. 2. ECG, heart rate \& blood pressure will be recorded at rest prior to each test. 3. Following overnight fasting and discontinuation of all medications for ≥ 12 hours and absence of \> 48 hour caffeine consumption, patients will receive 200 mg of caffeine tablets or placebo, in a double-blind, cross-over study design. An hour later the patient will undergo endothelium-dependent flow-mediated dilation (FMD) and endothelium-independent, nitroglycerin (NTG)-mediated vasodilation will be assessed non-invasively in the brachial artery, using a high resolution (15 MHz) linear array ultrasound. 4. Prior to and after the FMD, blood will be drawn to test caffeine levels, adiponectin, CBC, electrolytes, CRP and lipids.