Assessment of blood flow distal to coronary artery stenoses: Correlations between myocardial positron emission tomography and poststenotic intracoronary Doppler flow reserve

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 [¹⁵O]H₂O 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 stenose (left anterior descending 9: left circumflex, 2: mean, 59±23% diameter stenosis) underwent [¹⁵O]H₂O 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 lineary 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 [¹⁵O]H₂O PET regional myocardial perfusion and are useful for assessment of the physiological significance of coronary stenoses in humans.