46
Special Populations
Table 17. Invasive Coronary Function Testing Definition and
Linked Pharmacotherapy for INOCA Endotypes
Endotype Disorder of Coronary Artery Function
Microvascular
angina
(nonobstructive
CAD and
proven CMD)
Microvascular
resistance
IMR ≥25.
IMR is a quantitative method for
specifically assessing microvascular function
independent resting hemodynamics.
IMR is distal coronary pressure* transmit
time (average time for 3 saline bolus runs at
hyperemia).
Coronary
vasorelaxation
CFR by thermodilution <2.0.
This reflects the inability to increase coronary
flow above 2 times the resting flow.
Microvasodilator
capacity
Resistive reserve ratio <2.0.
This reflects the vasodilator capacity of the
microcirculation to change from baseline
to hyperemia (resistance at rest divided by
resistance at hyperemia).
Microvascular
spasm
Angina during acetylcholine infusion or
bolus with typical ischemic ST-segment
changes and epicardial coronary constriction
<90% reduction in epicardial coronary
artery diameter. Represents inappropriate
susceptibility microvascular constriction.
Vasospastic
angina
Epicardial spasm Epicardial coronary artery spasm is defined
as reduction in coronary diameter >90%
after intracoronary acetylcholine in
comparison with baseline resting condition
after intracoronary glyceryl trinitrate
(nitroglycerin) administration in any
epicardial coronary artery segment together
with symptoms and ST-segment deviation
on the ECG.
Mixed MVA/
VSA
CMD and
epicardial
vasospasm
Epicardial spasm plus any abnormality of:
• Microvascular resistance
• Coronary vasorelaxation
• Microvasodilator capacity
