Acute effects of vasoactive drug treatment on brachial artery reactivity.

OBJECTIVES The goal of this study was to investigate whether concomitant therapy with vasoactive medications alters the results of noninvasive assessment of endothelial function. BACKGROUND Ultrasound assessment of brachial artery flow-mediated dilation is emerging as a useful clinical tool. The current practice of withholding cardiac medications before ultrasound studies has unknown utility and would limit the clinical use of the methodology. METHODS To determine whether a single dose of a vasoactive drug influences brachial reactivity, we examined flow-mediated dilation and nitroglycerin-mediated dilation in 73 healthy subjects (age 27 +/- 6 years). Studies were completed at baseline and 3 h after randomized treatment with a single oral dose of placebo, felodipine (5 mg), metoprolol (50 mg), or enalapril (10 mg). To determine if holding vasoactive therapy for 24 h before study yields different results than continuation of clinically prescribed medications, we examined vascular function in 72 patients (age 57 +/- 10 years) with coronary artery disease. Ultrasound studies were performed 24 h after the last dose and again 3 h after patients took their clinically prescribed medications. RESULTS In healthy subjects one dose of all three drugs lowered blood pressure, and metoprolol also lowered heart rate. However, there was no significant effect of treatment on brachial artery dilation. In patients with coronary artery disease on chronic treatment, taking prescribed medications reduced blood pressure and heart rate, but had no significant effect on brachial artery dilation. CONCLUSIONS Recent administration of commonly used nonnitrate vasoactive drugs has no significant effect on brachial reactivity. These findings suggest that current practice of withholding cardiac medications before testing endothelial function may not be necessary, making this methodology more practical for clinical use.