Value of CMR-derived Quantitative Myocardial Blood Flow Assessment in The Setting of Chronic Coronary Occlusion.

Aims: For many years, visual assessment has been the mainstay of detecting obstructive coronary artery disease (CAD) by stress perfusion cardiovascular magnetic resonance (S-CMR). Recently, fully automated quantitative assessment of myocardial blood flow (MBF) has been introduced. The value of MBF quantification in patients with coronary chronic total occlusion (CTO) is unknown. In this study, we sought to investigate the diagnostic performance of CMR-derived fully automated quantitative MBF assessment in patients with CTO.

Methods: Consecutive patients who underwent S-CMR, as well as coronary angiography at our institution between 02/2023 and 11/2024 were included. S-CMR perfusion imaging was evaluated visually and quantitatively. Stenosis severity was assessed angiographically and >70% was considered severe stenosis.

Results: One hundred thirty patients (age 66.7 (59.7-75.2) years, 79.2% male) were included in this analysis. Patients were grouped according to CAD severity (non-obstructed coronary arteries <70%, n=57; severe stenosis >70%, n=37; CTO, n=36). Stress MBF (SMBF) and myocardial perfusion reserve (MPR) were significantly reduced in patients with CTO compared to those with severe stenosis and non-obstructed coronary arteries, respectively. Segmental SMBF <1.02 ml/g/min differentiated CTO from severe stenosis with a good predictive power (AUC: 0.792 (95% CI: 0.678-0.887)). Moreover, integrated visual and quantitative perfusion assessment provided high sensitivity in detecting additional severe stenosis in CTO patients (91.3%).

Conclusion: Addition of fully automated MBF quantification to clinical routine visual S-CMR reading facilitates non-invasive differentiation between CTO and severe stenosis and provides higher sensitivity regarding true ischemic burden in patients with CTO and multi-vessel disease, thereby aiding clinical decisionmaking.