Figure 2: Protocol for the Invasive Diagnostic Procedure.

The first step is the identification of coronary organic stenosis by diagnostic coronary angiography. In patients with significant organic coronary stenosis (>50% luminal narrowing), measurement of FFR should be considered. The second step is ACh provocation testing for coronary spasm. Additional evaluation for myocardial lactate production is useful to confirm the emergence of MVS without or prior to the development of epicardial coronary spasm. A case diagnosed with MVS is demonstrated. The third step is to perform wire-based assessment of CFR and IMR for evaluation of vasodilator microvascular capacity in response to adenosine. ACh = acetylcholine; CFR = coronary flow reserve; FFR = fractional flow reserve; IC = intracoronary; IMR = index of microcirculatory resistance; MVS = microvascular spasm; Pa = mean proximal coronary pressure; Pd = mean distal coronary pressure; T_mn = mean transit time.