INOCA: Non-Invasive Assessment of the Pathophysological Mechanisms Using CZT-SPECT MAGALI

pp. 185-192

Abstract

Background: One of the causes of INOCA (Ischemia with Non- Obstructive Coronary Arteries) is microvascular dysfunction
(MVD), which can be noninvasively assessed through the quantification of myocardial blood flow (MBF) and myocardial
flow reserve (MFR). 
Dynamic myocardial perfusion imaging (MPI) by CZT-SPECT at rest, with dipyridamole stress test and cold pressor test
(CPT) can establish the presence of two different pathophysiological mechanisms of MVD: endothelium-independent or
endothelium-dependent, respectively.
Objectives: The aim of this study was to evaluate the usefulness of CZT-SPECT for the diagnosis of MVD and the different
mechanisms involved in patients with INOCA.
Materials and Methods: A total of 93 consecutive INOCA patients were prospectively included and underwent dynamic
MPI with CZT-SPECT at rest and with dipyridamole stress test and CPT. THe MBF was quantified using 4DM® software. A
MFR response to dipyridamole <2, and changes in MBF (ΔMBF) <1.5 with CPT were considered abnormal responses. MVD
was defined in the presence of one abnormal response or both.
Results: CZT-SPECT detected MVD in 85% (n=79) of the patients with INOCA. Forty-two percent had an abnormal response
to both stressors while 43% presented an abnormal response of MBF only with CPT.
Conclusion: The use of CZT-SPECT with both stress tests allowed the evaluation of different possible pathophysiological
mechanisms of MVD present in most patients with INOCA.