Prevalence of coronary blood flow reserve abnormalities among patients with nonobstructive coronary artery disease and chest pain

Objective: To determine the prevalence of abnormalities in endothelium-depe ndent and endothelium-independent coronary Bow reserve among patients with nonobstructive coronary artery disease and chest pain. Material and Methods: We studied endothelium-dependent (after infusion of 1 0(-6) M to 10(-4) M of acetylcholine) and endothelium-independent (after ad ministration of 18 to 36 mu g of adenosine) coronary flow reserve among pat ients with nonobstructive coronary artery disease and chest pain who were u ndergoing assessment at Mayo Clinic Rochester. Coronary blood flow was deri ved from coronary artery diameter assessed by quantitative angiography and Doppler Bow velocities. Results: The cohort consisted of 203 patients (158 female and 45 mate patie nts), who ranged in age from 17 to 78 years (mean, 51), Most patients (92%) had at least one risk factor for atherosclerosis; a substantial proportion had undergone extensive cardiac and noncardiac evaluation. Whereas 41.5% o f the patients had normal coronary Bow reserve, 58.5% had an abnormal respo nse: 11.3% an impaired response to adenosine (flow velocity ratio of 2.5 or less), 29.2% an impaired response to acetylcholine (flow reserve ratio of 1.5 or less), and 18% a combined abnormality, No correlation (r(2) = 0.03) was noted between endothelium-dependent and endothelium-independent flow re serve. Conclusion: Most study patients with chest pain and nonobstructive coronary artery disease undergoing coronary vasomotor evaluation had risk factors f or coronary artery disease and diverse abnormalities in endothelium-depende nt or endothelium-independent coronary flow reserve (or both). These findin gs underscore the need for a comprehensive assessment.