Quantitative Assessment of Myocardial Viability and Ischemia in Patients with Coronary Artery Disease by Dobutamine Stress CMR Feature Tracking

Abstract Assessment of myocardial ischemia and viability is now mandatory for treatment decisions in patients with coronary artery disease (CAD). The high subjectivity of the noninvasive imaging tools such as dobutamine stress cardiovascular magnetic resonance (DS-CMR) in viability and ischemia assessment and late gadolinium enhancement (LGE) in scar transmurality detection, as well as the risks imposed by the contrast administration in patients with renal affection, paved the way for the evolution of more objective and safer techniques. Strain analysis provides quantifiable measurable values of the degree of myocardial deformation. Feature tracking-cardiac magnetic resonance (FT-CMR) is a novel strain analysis technique that uses only routinely acquired cine images in strain analysis. Our study aimed to assess the quantitative ability of the CMR-FT in assessment of myocardial ischemia and viability in patients with CAD. We investigated 20 patients (n = 320 myocardial segments), known or suspected CAD. DS-CMR and LGE were used to identify the viable non-ischemic, ischemic and non-viable myocardial segments. Then calculations of the rest segmental radial (Err), circumferential (Ecc) and longitudinal (Ell) strain were done by manual contouring of endocardial and epicardial borders using Segment Software. Results Based on the results of both DS-CMR and LGE of the 320 myocardial segments, 210 segments were defined as viable non-ischemic (remote), 71 segments were viable ischemic and 39 segments were non- viable. Rest segmental Ecc, Err and Ell values were statistically significantly reduced in the non-viable (mean± SD = -3.98 ± 5.08%, 12.26 ± 12.62% and -7.39 ± 7.05%, respectively) compared to both viable groups, p < 0.001. Furthermore, segmental Ecc and Err significantly differentiated between non-ischemic and ischemic group (mean± SD = -18.60 ± 7.09% vs -13.49 ± 8.53% and 44.09 ± 20.38% vs 32.21 ± 16.92% respectively), p1<0.001. However, Ell was weak to find a statistical significance between them, despite showing lower values in the ischemic group (mean± SD = -16.17 ± 8.86% vs -15.27 ± 9.82%, p = 0.741). Conclusions FT-CMR strain analysis can provide a more objective metric in myocardial strain analysis to differentiate between viable and non-viable as well as ischemic and non-ischemic myocardial segments. Therefore, such technique has a promising objective role in ischemia and viability assessment in conjunction with CMR or even may replace it in the future.