[Tracking Early Reperfused Myocardial Infarction using Cardiac MR]

Area of Science:

• Cardiology
• Biomedical Imaging
• Cardiovascular Research

Background:

• Reperfusion injury is a significant complication following myocardial infarction.
• Assessing early segmental myocardial changes is crucial for understanding recovery post-reperfusion.
• Cardiovascular magnetic resonance feature-tracking (CMR-FT) offers a non-invasive method to evaluate myocardial mechanics.

Purpose of the Study:

• To investigate segmental myocardial strain using CMR-FT in the early phase of reperfused myocardial infarction.
• To compare myocardial strain in patients and rats with varying degrees of infarction.
• To assess the temporal changes in myocardial strain after reperfusion.

Main Methods:

• Utilized MRI with steady-state free precession cine and late gadolinium enhancement sequences.
• Analyzed 16 AHA segments (excluding apex) for peak radial strain (RS) and circumferential strain (CS) using CVI software.
• Compared strain values in complete (CMI), partial (PMI), and non-myocardial infarction (NMI) segments in 10 patients and 10 rats.

Main Results:

• In both patients and rats, CMI and PMI segments showed significantly lower RS and CS compared to NMI segments (P < 0.01).
• No significant difference in strain was observed between CMI and PMI segments.
• In rats, segmental RS and CS increased over time (48h vs 7d, P < 0.05), while global strain remained unchanged.

Conclusions:

• Reperfusion injury in early myocardial infarction leads to decreased systolic function at the segmental level.
• CMR-FT effectively identifies impaired myocardial strain in infarcted segments.
• Segmental myocardial function shows potential for gradual recovery over time with reperfusion.