Unmet Need to Verify Coronary Artery Spasm in Patients with Chronic or Acute Coronary Syndrome and Non-Obstructive Coronary Arteries.

Coronary artery spasm (CAS) is a common endotype in patients with angina with non-obstructive coronary arteries. Pathophysiologically, the presence of CAS among arteries is not normal, as evidenced by several interacting mechanisms involving CAS development, including the endothelium, vascular smooth muscle cells, adventitia, autonomic nervous system, local inflammation, and systemic inflammation. Clinically, CAS is a dynamic process with a threshold effect on presentation; it can present as silent ischemia, atypical chest pain, resting angina, chronic coronary syndrome, acute coronary syndrome, variant angina, and even sudden cardiac arrest. Incomplete intracoronary provocation testing to exclude CAS as the etiology of chronic or acute coronary syndrome leads to an incorrect diagnosis and, subsequently, inappropriate treatment. Identification of the correct endotypes of chronic and acute coronary syndromes is critical for the selection of appropriate therapy, which thus affects disease outcome. Therefore, it is essential to complete intracoronary provocation testing for both the right and left coronary arteries to reach a correct diagnosis regarding CAS, including epicardial vasospasm and microvascular spasm. If CAS is found not to be the cause of myocardial ischemia, then a microvascular functional assessment is the next step to identify the etiology of the ischemic event. A comprehensive assessment of CAS is essential before appropriate treatments can be started.