0790
Diffusion Tensor CMR a potential early marker of remodelling after myocardial infarction1Royal Brompton Hospital, London, United Kingdom, 2Imperial College London, London, United Kingdom, 3National Institutes of Health, Bethesda, MD, United States
Synopsis
We performed a longitudinal large animal pre-clinical study to assess post-MI temporal alterations of myocardial microstructure, using Diffusion Tensor Cardiac Magnetic Resonance (DT-CMR). In vivo CMR was performed before, at 3 days, and 4 months after the reperfused MI procedure. Remodeled hearts demonstrated reduced right-handed helix angles in the endocardium of the infarct region, as well as a decreased gradient in the healix angle line profiles with associated thinning of the myocardium. Reduced sheetlet angle (E2A) mobility in the acute stage was associated with the development of adverse LV remodeling.
Introduction
Changes in myocardial microstructure that underlie post-myocardial infarction (MI) left ventricular (LV) remodelling may contribute to progressive deterioration in cardiac function and increased risk of adverse clinical events. We performed a longitudinal large animal pre-clinical study to assess post-MI temporal alterations of myocardial microstructure, using Diffusion Tensor Cardiac Magnetic Resonance1,2(DT-CMR).Methods
Animal procedures were approved by the National Heart, Lung, and Blood Institute Animal Care and Use Committee. Yucatan minipigs (N=8, ~40kg) underwent a 90 minute percutaneous balloon occlusion of the left circumflex (LCx, N=4) or left anterior descending (LAD, N=4) coronary artery just after the first diagonal/obtuse marginal branch, followed by reperfusion as previously described3. One animal died before completion of the longitudinal imaging protocol. In vivo CMR was performed before, at 3 days, and 4 months after the reperfused MI procedure. In vivo DT-CMR4 was performed at three mid-ventricular short axis slices at systole and diastole (b-value=500s/mm2, bref=50s/mm2, resolution 2x2x8mm3). After completion of in vivo imaging, animals were euthanised and hearts were excised and prepared for ex vivo imaging and histology. DT-CMR helix angle (HA), E2A and E2A mobility (ΔE2A = E2Asystole– E2Adiastole) were analysed4,5. ΔE2A in the acute stage was plotted against change (Δ) in left ventricular end diastolic volume (ΔLVEDV = LVEDV4months– LVEDVbaseline) and Δ left ventricular end systolic volume (ΔLVESV = LVESV4months– LVESVbaseline). Results
The in vivo 4-month HA maps in remodeled hearts demonstrated reduced right-handed helix angles in the endocardium of the infarct region, as well as a decreased gradient in the line profiles with associated thinning of the myocardium, consistent with ex vivo HA data (Figure 1), and with literature6. Acute ΔE2A (3 day after MI procedure) in the infarct and peri-infarct areas correlated both with ΔLVEDV and ΔLVESV (Figure 2).Discussion and Conclusion
Acute ΔE2A impairment was associated with the development of adverse LV remodeling. Abnormal sheetlet mobility (ΔE2A) at the acute stage of MI may be an early predictor of post-MI adverse LV remodeling. Acknowledgements
No acknowledgement found.References
1. Edelman et al. MRM 1994;32:423-428
2. Reese TG et al. MRM 1995;34:786-791
3. de Silva et al. EHJ 2008;29:1772- 1782
4. Nielles-Vallespin S et al. JACC 2017;69:6
5. Ferreira PF et al. JCMR 2014;16:87
6. Mekkaoui C et al. JCMR 2012; 14(Suppl 1) p35
Figures
(A) Helix Angle line profiles at healthy, 3 days and 4 months after myocardial infarction. Remote (green), peri-infarct (yellow) and infarct (red) areas. As the wall thins in chronic MI, the line gradient of the line profiles decreases.
(B) Helix Angle histograms at healthy, 3 days, and 4 months after myocardial infarction, in remote, peri-infarct and infarct zones. The bottom-right histogram demonstrates a decrease in right-handed helix angles in the endocardium of the chronic infarct zone.
