• microvascular dysfunction
• intracoronary acetylcholine-testing
• diffuse epicardial spasm
• diagnostic coronary angiography
• adenosine-stress perfusion-CMR
• unobstructed coronaries

At least 10% to 30% of patients presenting with angina have no significant coronary artery disease on invasive coronary angiography as many as 50% to 65% of these patients with chest pain with unobstructed coronaries are believed to have functional coronary vasomotor abnormalities (i.e. isolated microvascular dysfunction and/or associated with diffuse epicardial spasm). Between 2012 and 2014 we consecutively recruited 128 patients with angina pectoris who underwent an adenosine-stress perfusion-CMR study and invasive diagnostic coronary angiography because of suspected obstructive coronary artery disease. Twenty-eight patients (22%) presented with effort-induced angina, 75 patients (59%) with resting angina, 19 patients (15%) had a balanced presentation of effort and rest angina and 6 patients (5%) had other symptoms. In all patients no relevant epicardial stenosis was found (<50% narrowings) and intracoronary ACH-testing was performed in search of functional coronary vasomotor abnormalities.
An adenosine-induced, reversible subendocardial perfusion defect was detected in 58 (45%) patients whereas CMR-perfusion was normal in 70 patients (55%). ACH-testing revealed a pathologic vasomotor response in 90 patients (70%) of whom 59 (48%) patients had coronary microvascular dysfunction (reproduction of symptoms, ischemic ECG-changes and no epicardial spasm)and 31 (24%) had diffuse epicardial coronary spasm (≥75% diameter reduction with reproduction of the patient’s symptoms).The ACH-test was uneventful in 38 patients (30%). Patients with a reversible stress-induced perfusion defect had significantly more often a pathological ACH-test (52/58; 90%) than those without a perfusion defect (38/70; 54%; p<0.01). Reversible perfusion defects on stress perfusion-CMR in patients with angina and unobstructed coronary artery disease are frequently due to coronary vasomotor abnormalities. Acetylcholine provocation testing may be useful in these patients to determine the cause of angina and initiate appropriate medical treatment