Central Illustration.

Identifying Mechanisms of Ischemia With Nonobstructive Coronary Arteries With Invasive Coronary Angiography

A systematic approach to diagnose ischemia with nonobstructive coronary arteries (INOCA) and define the underlying mechanisms is presented. The first step is excluding flow-limiting epicardial coronary artery disease using invasive coronary angiography. Invasive physiologic assessment using fractional flow reserve (FFR) or nonhyperemic pressure ratio (NHPR) and/or invasive coronary imaging is helpful. After excluding the presence of ischemia-causing epicardial lesions, comprehensive physiologic assessments should be performed to identify the microvascular dysfunction. Finally, provocation tests are helpful in the diagnosis of vasospastic angina. HMR = hyperemic microvascular resistance; IMR = index of microvascular resistance.