P-107: A single cup of coffee increases wave reflection

Background: Caffeine (C) is the most widely consumed pharmacologically active substance. However, its effects on the arterial system have not been thoroughly investigated. Wave reflection along the arterial tree, an important index of arterial stiffening and cardiac afterload, is involved in the pathogenesis of isolated systolic hypertension. Methods: To investigate the acute effect of a single cup of coffee on arterial wave reflection we studied 10 healthy volunteers (age 29±4 years) in a randomized, double-blind, crossover fashion (100 mg of caffeine orally -equivalent to 1 cup of coffee- and placebo). Wave reflection was studied using a validated system (Sphygmocor®) that employs (i) high-fidelity arterial tonometry (Millar tonometer) for the non-invasive registration of radial pulse waveform and (ii) appropriate computer software for pulse wave analysis. Aortic pressure waveform was synthesized from the radial waveform using a generalized transfer function. Augmentation index (AI=dP/PP, fig.: waveform) was measured as an index of wave reflection. Inflection point (Pi) was defined with mathematical algorithms. Higher values of AI indicate increased arterial stiffening and increased cardiac load and vice-versa. Results: C lead to a substantial increase in AI indicating increased effect of wave reflection from the periphery (figure trends). Systolic pressure was increased by 3 mmHg and diastolic pressure by 6.5 mmHg. No changes were observed after placebo. Conclusions: A single cup of coffee leads to an acute increase of wave reflection. This finding has important implications for arterial stiffening and the pulsatile load of the heart and may be involved in the pathogenesis of hypertension.