Characterizing early ventricular inefficiency in MINOCA using four-dimensional flow cardiovascular magnetic resonance
X D Zhao, P Yang, R S Tan, P T Lee, L S Teo, M Y Hu, S Leng, A Koh, P Chai, D Zong, R Geest, P Garg, L Gong, L ZhongAbstract
Background
Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a heterogeneous condition with incompletely understood mechanisms. Early diastolic filling contributes to ventricular efficiency and reflects myocardial relaxation and compliance, which may be altered by coronary microvascular dysfunction.
Purpose
We aimed to determine whether patients with MINOCA demonstrate impaired early diastolic filling efficiency, quantified by early filling blood kinetic energy using four-dimensional flow cardiovascular magnetic resonance (4D flow CMR).
Methods
46 MINOCApatients and 50 healthy controls without known cardiovascular disease were included in this study, and all underwentcine and 4D flow MRI. Using MASS software, automated segmentation of the LV endocardial and epicardial borders was performed using an artificial intelligence–based algorithm to derive conventional LV volumes and myocardial mass, with manual adjustments performed when necessary, according to Society for Cardiovascular Magnetic Resonance recommendations. Four LV flow components (direct flow, retained inflow, delayed ejection flow and residual volume) and LV kinetic energy parameters normalized to LV end-diastolic volume (KEiEDV) were derived.
Results
See Table. Compared with controls, patients with MINOCA exhibited marked alterations in LV flow energetics, characterized by reduced LV direct flow (15% vs. 33%, P<0.001) and increased LV residual volume (47% vs. 35%, P<0.001), together with significantly decreased KEiEDV parameters. Peak E-wave KEiEDV demonstrated excellent discriminatory performance for identifying MINOCA (AUC = 0.898). Applying a threshold derived from the control population (mean − 1 SD; 12.50 μJ/mL), impaired early filling efficiency was detected in 74% of MINOCA patients.
Conclusion
These findings indicate that a substantial proportion of MINOCA patients have reduced early diastolic blood kinetic energy, reflecting impaired ventricular filling efficiency and potentially underlying abnormalities in myocardial relaxation, ventricular compliance, and coronary microvascular function.