Does Coronary Microvascular Spasm Exist? Objective Evidence from Intracoronary Doppler Flow Measurements During Acetylcholine Testing

A 43-year-old woman with recurrent atypical angina underwent invasive coronary angiography including intracoronary Doppler blood flow assessment and coronary spasm provocation testing. While obstructive epicardial disease could be ruled-out angiographically, the patient experienced reproduction of her angina symptoms after intracoronary administration of acetylcholine (100 µg) during spasm provocation testing. Simultaneously, the ECG showed new-onset ST-segment depression in the absence of epicardial spasm. In addition, coronary flow velocity was significantly reduced after acetylcholine compared to the baseline condition. Following intracoronary administration of nitroglycerine (200 µg), the patient’s symptoms as well as the ECG changes and coronary flow reduction were reversed. Considering the ongoing challenges in appropriate evaluation of the pathophysiological mechanisms of coronary microvascular dysfunction, simultaneous intracoronary Doppler flow measurement during spasm testing – as shown in this case – may provide objective evidence for microvascular spasm in addition to the standardized diagnostic criteria, especially if they are ambiguous.