Comparison between positron emission tomography myocardial perfusion imaging and intracoronary Doppler flow velocity measurements at rest and during cold pressor testing in angiographically normal coronary arteries in patients with one-vessel coronary artery disease

With use of invasive methods, coronary endothelial function is generally studied by examining the response of epicardial coronary arteries to intracoronary administered acetylcholine or to cold presser testing. Because invasive methods have substantial inherent limitations, studies should attempt to evaluate coronary endothelial function noninvasively. This study examines a noninvasive technique for endothelium-related coronary stress testing. In myocardial regions supplied by nonstenotic coronary arteries, we compared positron emission tomography (PET) myocardial perfusion imaging with intracoronary Doppler flow velocity measurements during endothelium-related stress testing. PET perfusion was examined at rest and during cold presser testing in 10 patients with 1-vessel coronary artery disease. In nonstenotic coronary arteries, flow velocity measurements were obtained at rest, during cold presser testing, and during intracoronary administered acetylcholine. Perfusion and flow velocity responses and stress/rest ratios were compared between the techniques during the various circumstances. Positive correlations were found between: (1) cold presser Doppler flow velocity responses and acetylcholine Doppler flow velocity responses (r = 0.84, SEE = 0.19, p = 0.003); (2) cold presser PET perfusion responses and cold presser Doppler flow velocity responses (r = 0.70, SEE = 0.17, p = 0.02); and (3) cold presser PET perfusion responses and acetylcholine Doppler flow velocity responses (r = 0.62, SEE = 0.19, p = 0.05). These results suggest that in angiographically normal coronary arteries, both the flow velocity and the perfusion responses during cold presser testing may be related to the response to acetylcholine.