Abstract 5806: A Novel Quantification of Local Circumferential Myocardial Stress using Newly Developed Software System
Local myocardial stress is important to evaluate stress-strain relationships in the left ventricle (LV). We developed a novel software package to assess local circumferential myocardial stress with LV long-axis images obtained by 64-row multidetector computed tomography (MDCT) and cardiac magnetic resonance (CMR) imaging. We compared local average circumferential stress (local σ) using our method with global equatorial circumferential stress (global σ) derived from conventional left ventriculography (LVG). We acquired 30° right anterior oblique LVG images in 74 patients with LV hypertrophy (aortic regurgitation; n=48, aortic stenosis; n=26) and 26 healthy subjects. The images were stored as audio video interleave files, transferred to a computer for offline analysis, manually traced at end-systole and end-diastole, and analyzed using Janz’s formula to elucidate local σ in segment #12 (mid antero lateral) based on AHA/ASE criteria. Global σ was obtained using Mirsky’s formula. Intra- and inter-observer variabilities were evaluated using the end-diastolic frames of 40 images. A highly significant correlation was found between local σ and global σ (r=0.99, p<0.001). Bland-Altman analysis also showed good agreement between the two methods (mean bias 2.4 kdyn/cm2, limits of agreement 9.3 kdyn/cm2/−4.6 kdyn/cm2) (Figure⇓). The intra- and inter-observer variabilies for the stress measurements were 2.9% and 3.6%, respectively. Our novel software package may be useful to assess local circumferential myocardial stress with contemporary cardiovascular imaging techniques.