Concordance of nutritive myocardial perfusion reserve and flow velocity reserve in conductance vessels in patients with chest pain with angiographically normal coronary arteries

We have previously shown that myocardial perfusion can be quantified by positron emission tomography (PET) with ¹⁵O-labeled water (H₂ ¹⁵O), as experimentally validated with radiolabeled microspheres in animal hearts. The purpose of our study was to determine whether myocardial nutritive perfusion reserve assessed with PET in human subjects was parallel to flow velocity reserve assessed in conductance vessels measured with intracoronary Doppler probes. We studied nine patients with chest pain and angiographically normal coronary arteries with intracoronary Doppler flow velocity assessments before and after administration of 16 μg of intracoronary adenosine. We also assessed myocardial nutritive perfusion with PET and H₂ ¹⁵O before and after intravenous administration of dipyridamole (0.56 mg/kg). Perfusion reserve (the ratio of absolute values of myocardial perfusion after dipyridamole administration to perfusion at rest) estimated with PET (3.5 ± 0.9 s.d.) correlated closely with flow velocity reserve (the ratio of hyperemic intracoronary flow velocity to flow velocity at rest) (3.5 ± 1.2, r = 0.80, p < 0.01). Absolute values of perfusion assessed tomographically averaged 1.22 ± 0.19 ml/g/min in patients at rest and 4.16 ± 0.93 after dipyridamole administration. Our data indicate that noninvasive assessment of myocardial perfusion with PET provides results that parallel intracoronary Doppler flow velocity measurements. Because PET delineates nutritive perfusion throughout the heart in absolute terms, its use may facilitate detection of impaired coronary arterial function and enhance delineation of the efficacy of potentially therapeutic interventions in patients with chest pain and angiographically normal coronary arteries.