Abstract 20288: Quantification and Z-Score “Normalization” of Regional Myocardial Contractile Data in Ischemic Coronary Artery Disease Patients

Abstract

Introduction: Left ventricular (LV) regional contractile information is currently limited to subjective interpretation of low-resolution echocardiography. In order to establish a more specific and standardized form of imaging, this study compared strain patterns in normal patients to patients with coronary artery disease (CAD) using high-resolution contractile data from cardiac MRI. Methods: Sixty normal test subjects underwent cardiac MRI with multiple 3D strain parameters calculated from tissue tag-plane displacement data. 15,300 LV grid points contributed to a normal human strain database. Sixty patients with known CAD underwent cardiac MRI. Normalized z-scores for 3 strain parameters at each of the LV grid-points were calculated by comparing raw strain values to the normal database. The z-scores at each point were then averaged to generate 15,300 normalized strain z-scores. Clinical evidence for prior ischemic events was sought in each patient’s medical record. Results: Multi-parametric strain information was successfully obtained in all 60 CAD patients with post-processing display of “quantified” regional ischemic injury over patient-specific LV geometry. We displayed “normalized” micro-regional contractile function by intuitive z-score color-coding of regions (<1 standard deviation=blue; 1-2=yellow; >2=red) over patient-specific 3D LV geometry (Figure). Clinical evidence for prior ischemic events obtained from echo, viability studies, ECG, and left heart catherization correlated well with regional injury patterns. Conclusions: The quantitative “normalization” of raw patient-specific values by z-score calculation from a normal human strain database can effectively create vivid displays of prior ischemic events. These high-resolution images provide detailed contractile information that may shape a new paradigm in preoperative surgical evaluation prior to revascularization.