Assessment of Blood Flow Distal to Coronary Artery Stenoses

Background Previous studies have correlated quantitative coronary angiographic stenosis severity with positron emission tomography (PET) myocardial perfusion and proximal measurements of intracoronary flow velocities in normal and diseased coronary arteries. The aim of this study was to correlate regional myocardial blood flow (RMBF) derived from 15 OH 2 O PET with directly measured poststenotic intracoronary Doppler flow velocity data acquired under basal conditions and dipyridamole-induced hyperemia. Methods and Results Eleven consecutive patients 53±13 years old with ischemic chest pain and isolated proximal left coronary artery stenoses (left anterior descending, 9; left circumflex, 2; mean, 59±23% diameter stenosis) underwent 15 OH 2 O myocardial PET and intracoronary Doppler flow velocity studies within 1 week. PET RMBF (mL·g −1 ·min −1 ) and myocardial perfusion reserve (MPR) were calculated in poststenotic and normal reference vascular beds. Poststenotic Doppler average peak flow velocities (APV; cm/s) and coronary flow velocity reserve (CFR) were compared with corresponding PET data and quantitative angiographic lesional parameters. PET RMBF and Doppler APV were linearly correlated ( r =.60; P <.001), as were poststenotic PET MPR and Doppler CFR ( r =.76; P <.0002). Relative coronary flow velocity and MPR ratios between poststenotic and angiographically normal vascular beds were comparably reduced (0.83±0.25 versus 0.86±0.21, respectively; P =NS). Conclusions Intracoronary Doppler flow velocities acquired distal to isolated left coronary artery stenoses correlated with 15 OH 2 O PET regional myocardial perfusion and are useful for assessment of the physiological significance of coronary stenoses in humans.