Quantitative perfusion by cardiac magnetic resonance analysis reveals compromised myocardial perfusion in patients with angina with non-obstructive coronary artery disease

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Abstract Introduction Stress perfusion cardiac magnetic resonance (CMR) visually detects myocardial ischemia through first-pass contrast-enhanced imaging by identifying perfusion defects. However, in generalized myocardial diseases like angina with non-obstructed coronary arteries (ANOCA), visual assessment becomes challenging due to diffuse sub-endocardial perfusion defects, or the findings may even falsely appear normal. Fully automated quantitative perfusion (QP), allowing absolute quantification of myocardial blood flow (MBF) and deriving myocardial perfusion reserve (MPR), might increase diagnostic accuracy in ANOCA patients. Therefore, the purpose of this study is to test the use of QP in detecting ANOCA diagnosed by the invasive golden standard. Methods This study is a cross-sectional cohort study assessing the use of fully automated QP CMR in patients with ANOCA compared with age- and sex-matched healthy controls. All participants underwent adenosine stress perfusion CMR, including visual assessment and quantification of MBF and MPR. Furthermore, all ANOCA patients underwent intracoronary function testing (ICFT) to idenity vasospasm and/or coronary microvascular dysfunction. Results This study included 24 ANOCA patients (83% women, 56.8±8.9 years) and 25 healthy controls (80% women, 56.2±7.2 years). Visual perfusion assessment showed no group differences in terms of perfusion defects (p=0.536). However, in QP, ANOCA patients had higher relative MBF than healthy controls (0.83±0.15 vs 0.74±0.17, p=0.046), while global perfusion was significantly lower during stress (2.43±0.72 vs 2.99±0.65 ml/g/min, p=0.006). Moreover, ANOCA patients had significantly lower MPR than healthy controls (2.24 ±0.79 vs 2.68 ±0.64, respectively p=0.036), with a higher prevalence of an impared MPR (50% vs. 20%, p=0.027). MPR was not significantly different between the various ANOCA entities as stratified during ICFT (p=0.766). Conclusions ANOCA patients displayed significantly reduced MPR, indicating impaired perfusion. The prevalence of diminished MPR was higher in the ANOCA group compared to the healthy controls, constrasting with no differences in visual assessment. These results are promising and underscores the possibilities of the use of QP in detecting vasomotor dysfunction non-invasively in ANOCA patients.Quantitative Perfusion by CMR results