A high-fidelity geometric multiscale hemodynamic model for predicting myocardial ischemia

Area of Science:

• Cardiovascular Imaging
• Computational Fluid Dynamics
• Medical Modeling

Background:

• Current coronary computed tomography angiography (CCTA) derived fractional flow reserve (CT-FFR) relies on a simplified assumption of maximal hyperemia.
• This assumption overlooks individual patient vasodilator capacity, potentially limiting accuracy in predicting myocardial ischemia.
• There is a need for non-invasive methods that better characterize coronary hemodynamics under resting conditions.

Purpose of the Study:

• To develop and validate a high-fidelity geometric multiscale model (HFMM) for characterizing coronary pressure and flow.
• To predict myocardial ischemia using CCTA-derived instantaneous wave-free ratio (CT-iFR) under resting state conditions.
• To compare the accuracy and efficiency of CT-iFR with invasive FFR and CT-FFR.

Main Methods:

• A patient-specific coronary microcirculation resistance hemodynamic model (RHM) was established under resting conditions.
• The RHM was coupled with a closed-loop geometric multiscale model (CGM) to create the HFMM.
• CT-iFR was non-invasively derived from CCTA images in 57 patients (62 lesions) referred for invasive FFR.

Main Results:

• CT-iFR demonstrated higher accuracy (90.32%) in identifying myocardial ischemia compared to CCTA (79.03%) and CT-FFR (84.3%), using invasive FFR as the reference.
• The computational time for CT-iFR was significantly faster (61 ± 6 min) than CT-FFR (8 hours).
• CT-iFR showed high sensitivity (96%) and specificity (92%) in discriminating invasive FFR > 0.8.

Conclusions:

• A high-fidelity geometric multiscale hemodynamic model enables rapid and accurate CT-iFR estimation.
• CT-iFR offers advantages over CT-FFR, including reduced computational cost and the ability to assess tandem lesions.
• This novel approach improves non-invasive assessment of coronary artery disease and myocardial ischemia.