Wave reflections from the periphery of the systematic circulation are known to be important determinants of the morphology of aortic pressure waveforms. Similar data regarding the effects of coronary microcirculation on intracoronary pressure waveforms are limited. We sought to investigate whether drug-induced changes of coronary microcirculation are reflected in the modification of intracoronary pressure waveforms. In eighteen patients with normal myocardial contractile function we studied pressure waveforms recorded by a high-fidelity pressure wire at the ostium and at a distal site of left anterior descending coronary artery, which had to be free of significant lesions in the epicardial and the microvascular segment, i.e. fractional flow reserve >0.75, corrected TIMI frame count <27 and coronary flow reserve by thermodilution >2.5. Pressure recording was performed both at rest and at hyperemia induced by intravenous infusion of adenosine. Analysis of pressure waveforms at the frequency domain was performed with Fast Fourier Transform. At baseline conditions, distal vs proximal pressure waveforms were characterized by higher pulsatility: higher fractional pulse pressure ΔPPf (p = 0.009), a higher presystolic wave probably due to atrial contraction (p < 0.001) and higher amplitude of the eleventh to the fifteenth harmonics (p = 0.001). Hyperemia increased ΔPPf (p = 0.01), compressed the notch and decreased the amplitude of higher than the tenth harmonics of distal waveforms (p < 0.001) (Figure).

The configuration of intracoronary pressure waveforms is significantly affected by the status of coronary microcirculation. Therefore, their analysis may facilitate assessment of microvascular disease.