Table 1

Definitions of ANOCA disease endotypes

Disease endotype	Mechanism	Invasive diagnostic test
Microvascular angina	↑ Microvascular resistance	IMR ≥25
	↓ Coronary vasorelaxation	CFR <2.0
	↓ Microvascular vasodilator capacity	RRR <2.0
	Microvascular spasm	ACh testing: angina, ischaemic ST segment deviation, epicardial coronary vasoconstriction <90%.
Vasospastic angina	Epicardial spasm	ACh testing: angina, ischaemic ST segment deviation, >90% epicardial coronary vasoconstriction.
Mixed microvascular and vasospastic angina	CMD and epicardial vasospasm	Epicardial vasospasm and either ↑ microvascular resistance, ↓ coronary vasorelaxation or ↓ microvascular vasodilator capacity.
Obstructive epicardial CAD	Epicardial stenosis	>50% lesion by diameter stenosis in epicardial artery >2.5 mm or FFR ≤0.80.
Non-cardiac pain	Nil	Exclusion of epicardial (FFR >0.8), microvascular (CFR >2.0, IMR <25, RRR >2.0) vasospasm (normal ACh response).

ACh, acetylcholine; ANOCA, angina with no obstructive coronary artery disease; CAD, coronary artery disease; CFR, coronary flow reserve; CMD, coronary microvascular dysfunction; FFR, fractional flow reserve; IMR, index of microcirculatory resistance; RRR, relative resistance ratio.