TABLE 1

Invasive coronary function testing in patients with INOCA: Three medications

Drug administered	Results	Diagnosis
1. Adenosine	Coronary flow reserve < 2.5	Nonendothelial-dependent microvascular dysfunction
2. Acetylcholine	< 50% increase in coronary blood flow	Endothelial-dependent microvascular dysfunction
	< 5% increase in coronary artery diameter	Endothelial-dependent macrovascular dysfunction
	> 90% decrease in coronary artery diameter Chest pain and ischemic ST-segment changes on electrocardiography	Epicardial coronary spasm
	Chest pain and ischemic ST-segment changes on electrocardiography in the absence of significant epicardial coronary vasoconstriction	Microvascular coronary spasm
3. Nitroglycerin	< 20% increase in coronary artery diameter	Nonendothelial-dependent macrovascular dysfunction

INOCA = ischemia and no obstructive coronary artery disease (ie, < 50% stenosis)