Assessment of Microcirculatory Remodeling With Intracoronary Flow Velocity and Pressure Measurements Validation With Endomyocardial Sampling in Cardiac Allografts

Background— Intracoronary physiology techniques have been validated extensively for the assessment of epicardial stenoses but not for the lone study of coronary microcirculation. We performed a comparison between 4 intracoronary physiological indices with the actual structural microcirculatory changes documented in transplanted hearts. Methods and Results— In 17 cardiac allograft patients without coronary stenoses, ECG, intracoronary Doppler flow velocity, and aortic pressure were digitally recorded before and during maximal hyperemia with a dedicated system. Postprocessing of data yielded 4 indices of microcirculatory status: coronary flow velocity reserve (2.13±0.59), instantaneous hyperemic diastolic velocity pressure slope (2.33±1.25 cm · s · −1mm Hg−1), coronary resistance index (1.65±0.88 mm Hg · cm−1 · s−1), and coronary resistance reserve (2.36±0.65). Quantitative morphometry was performed in endomyocardial biopsies during the same hospital intake; arteriolar obliteration (76.57±6.95%) and density...