Coronary microvascular dysfunction (CMD) relates to a broad range of clinical settings in which cardiac microcirculation is morphologically and/or functionally affected, leading to myocardial ischemia and causing anginal symptoms (microvascular angina).
Based on the pathogenetic mechanism, there are two possible endotypes of CMD: 1) coronary microvascular spasm and 2) reduced coronary flow reserve (CFR). The gold standard for CMD diagnosis is represented by the coronary angiography with functional tests: 1) the acetylcholine provocative test for the diagnosis of microvascular spasm (endothelium-dependent dysfunction); 2) the determination of CFR and of the index of microvascular resistance (IMR) thorough a flow guidewire after endothelium-independent vasodilation (usually obtained with intracoronary adenosine injection).
We report an emblematic case of CMD due to microvascular spasm in a young woman with episodes of typical angina at rest, especially during the night, associated with tachycardia episodes. The patient was admitted to the cardiology unit and underwent coronary angiography, which revealed mild coronary atherosclerosis without any significant stenosis. Due to the very suggestive clinical presentation, provocative test by intracoronary acetylcholine infusion at increasing doses (20-50-100 micrograms) was also performed: from the beginning of the second dose (50 micrograms) the patient started suffering from her typical angor (symptomatology similar to that reported at home), and diffuse ST-T alterations (ST depression and T waves inversion in precordial leads) occurred. At the beginning of the third dose (100 micrograms) a lateral ST-segment elevation (mostly in aVL) was surprisingly observed. The ST-T modifications (including the elevation) were interestingly associated with only diffuse moderate vasoconstriction of the left anterior descending artery, not fulfilling the Covadis criteria for epicardial vasospasm, thus suggesting the presence of a vasospasm of the coronary microcirculation. Symptoms and ECG changes both regressed after intracoronary nitrates administration.
As a consequence of the diagnosis of microvascular angina with microvascular vasospasm, medical therapy with calcium antagonists was administered (withdrawing beta-blockers).
