Hybrid Imaging to Assess the Impact of Vulnerable Plaque on Post Myocardial Infarction Myocardial Scar

Abstract Background: Multimodality imaging improves the accuracy of cardiac assessment in patients with prior myocardial infarction. The aim of this study was to investigate the association between coronary plaque vulnerability (PV) and myocardial viability in the territory irrigated by the infarct-related artery (IRA). Secondary objectives include evaluation of the systemic inflammation but also different cardiac risk scores (SYNTAX score, Duke jeopardy score, or calcium score) using hybrid imaging models of coronary computed tomography angiography (CCTA) and cardiac magnetic resonance (CMR) in patients who have suffered a previous myocardial infarction (MI). Material and methods: The study included 45 subjects with documented MI in the 30 days prior to study enrolment, who underwent CCTA and CMR examinations. Computational postprocessing of CCTA and CMR images was used to generate fused imaging models. Based on the vulnerability degree of the associated non-culprit lesion located proximally in the IRA, the study population was divided into 3 groups: Group 1 – subjects with no sign of vulnerability (n = 7); Group 2 – subjects with 1 or 2 CT vulnerability features (n = 28); and Group 3 – subjects with >2 features of vulnerability (n = 12). Results: CCTA features indicative for the severity of coronary artery disease were not different between groups in terms of calcium scoring (460 ± 501 vs. 579 ± 430 vs. 432 ± 494, p = 0.7) or SYNTAX score (25 ± 9.2 vs. 24.9 ± 8.3 vs. 20.2 ± 11.9, p = 0.4). However, after 1 month, infarct size and the Duke jeopardy score were associated with increased PV (infarct size 8.77 ± 3.4 g in Group 1, compared to 20.87 ± 8.3 g in Group 2 and 27.99 ± 11.8 g in Group 3 (p = 0.007), while the Duke jeopardy score was 4.4 ± 1.6 in Group 1, vs. 7.07 ± 2.1 in Group 2 vs. 7.5 ± 1.73 in Group 3 (p = 0.01). Inflammatory biomarkers were directly associated with coronary plaque vulnerability (p = 0.007 for hs-CRP and p = 0.038 for MMP-9). Conclusion: In patients with prior myocardial infarction, the size of myocardial scar was directly correlated with the vulnerability degree of coronary plaques and with systemic inflammation quantified during the acute phase of the coronary event. Hybrid imaging may help to identify the hemodynamically significant plaques with superior accuracy.