Prevalence and disease features of myocardial ischemia with non-obstructive coronary arteries: Insights from a dynamic CT myocardial perfusion imaging study

Background: Ischemia with non-obstructive coronary arteries (INOCA) is not uncommon in clinical practice. However, the incidence and imaging characteristics of INOCA on dynamic CT myocardial perfusion imaging (CT-MPI) remains unclear. We aimed to investigate the prevalence and disease features of INOCA as evaluated by dynamic CT-MPI + coronary CT angiography (CCTA).

Methods: Patients with suspected chronic coronary syndrome and intermediate-to-high pre-test probability of obstructive CAD (according to updated Diamond and Forrester Chest Pain Prediction Rule) were referred for dynamic CT-MPI + CCTA and retrospectively included. Various parameters, including myocardial blood flow (MBF) and high-risk plaque (HRP) features, were measured. INOCA was diagnosed if patients were revealed to have myocardial ischemia and absence of obstructive stenosis.

Results: 314 patients were finally included. 20 patients (6.4%) were observed to have myocardial ischemia without obstructive stenosis. In addition, 138 patients (43.9%) had normal or near normal findings, 101 patients (32.2%) had obstructive stenosis without myocardial ischemia and 55 patients (17.5%) had obstructive stenosis with myocardial ischemia. Compared with patients with normal/near normal findings, patients with INOCA showed a higher prevalence of positive remodeling (40.0% vs. 17.4%, p = 0.04). In patients with obstructive stenosis, the mean age, calcium score and incidence of spotty calcification, positive remodeling as well as HRPs were significantly higher than those in patients with INOCA (p < 0.05 for all).

Conclusions: The overall prevalence of INOCA was low in patients with suspected chronic coronary syndrome. HRPs were less frequently presented in patients with INOCA, compared with patients having obstructive coronary stenosis.