Transient Myocardial Ischemia During Acetylcholine-Induced Coronary Microvascular Dysfunction Documented by Myocardial Contrast Echocardiography

A 77-year-old white woman was referred for diagnostic coronary angiography after a 6-month history of exertional breathlessness and back pain. Her cardiovascular risk factors were hypercholesterolemia (low-density lipoprotein, 153 mg/dL) and a positive family history for cardiovascular disease (father died at 73 years of age because of a peripheral artery occlusive disease event). Furthermore, the patient was overweight (body mass index, 28.8 kg/m2). Exercise ECG stress testing had to be stopped after 75 W as a result of limiting symptoms (breathlessness) but without ST-segment depression.Diagnostic coronary angiography revealed a 50% plaque in the distal circumflex coronary artery and diffuse minor irregularities in the remaining epicardial vessels (Figure 1). However, there was no flow-limiting epicardial stenosis. Left ventricular angiography showed normal left ventricular function without any wall motion abnormalities at rest, although left ventricular end-diastolic pressure was elevated at 25 mmHg. To further investigate the cause of the patient’s symptoms, intracoronary acetylcholine …