Exploring coronary microvascular function by quantitative CZT-SPECT: a small step or giant leap for INOCA patients?

Excerpt

In the wide coronary artery disease (CAD) scenario, ischemia with nonobstructive coronary arteries (INOCA) represents a challenging condition, both for the late diagnosis and unfavorable prognosis [1‐3]. Commonly, INOCA patients show clinical symptoms suggestive for ischemia, such as typical/atypical angina-like chest pain, along with instrumental proof of myocardial ischemia, and no evidence of obstructive coronary stenosis at invasive coronary angiography (ICA) or coronary CT angiography (CCTA) [4]. Although according to different studies [5, 6], the definition of “nonobstructive CAD” may range from a threshold of < 50 to < 70% coronary stenosis and it has not a univocal cut-off, the overall trend shows that up to half of the patients with ischemia symptoms referred to ICA results to have nonobstructive disease [1, 7, 8]. Nevertheless, these patients present an increased occurrence of major adverse cardiovascular events (MACEs) at long-term follow-up, highlighting the need for an early diagnosis to improve risk stratification and management of INOCA patients [3, 9]. Despite the lack of knowledge on the exact physiologic mechanism underlying INOCA, more evidence is emerging on the role of coronary microvascular disease (CMD), which is strictly linked to coronary endothelial dysfunction and coronary flow reserve (CFR) impairment [2, 7]. …