Noninvasive Ultrasound Study of Acute Myocardial Infarction in Different Pathological Phases.

OBJECTIVE

By evaluating the myocardial mechanics and microcirculation perfusion in different pathological phases of acute myocardial infarction (AMI) using speckle tracking imaging (STI) and myocardial contrast echocardiography (MCE). we aim to provide a non-invasive ultrasound diagnosis strategy to distinguish different pathological phases of AMI.

METHODS

The C57/BL6 mouse model of acute myocardial infarction (AMI) was created by ligating the left anterior descending coronary artery. Microvessel density (MVD) and pathological changes in the infarct area were analyzed quantitatively and qualitatively using TTC, HE, Masson staining, immunohistochemistry, and immunofluorescence during the inflammatory, proliferative, and mature phases. Global longitudinal strain (GLS), circumferential strain (GCS), and radial strain (GRS) were measured by STI, while myocardial perfusion peak enhancement (PE) and Wish-in-rate (WIR) were measured by MCE.

RESULTS

For the inflammatory phase, MVD was 52.8/0.1mm², and inflammatory factors IL-6, IL-1β, and TNFα were up-regulated. WIR showed the best accuracy at this phase, with a value of 12.29 ± 2.24 dB, AUC of 0.93, sensitivity of 1.00, specificity of 0.83, and cut-off of 9.24. For the proliferative phase, MVD dropped to 21.6/0.1mm²; GLS and WIR had high diagnostic performance, with AUCs of 0.89 and 0.97, sensitivities of 0.75 and 1.00, and specificities of 1.00 and 0.91, respectively. In the mature phase, the infarct area became fibrotic, inflammatory factors disappeared, and MVD decreased to 8.6/0.1mm². GRS analysis has diagnostic value, with an AUC of 0.77, sensitivity of 0.91, specificity of 0.66, and a cut-off of 14.36. PE maintained high diagnostic accuracy, with an AUC of 0.93, sensitivity of 1.00, specificity of 0.75, and a cut-off of 5.47.

CONCLUSION

The combination of MCE and STI can act as a reliable non-invasive ultrasound diagnosis to distinguish different pathological phases of AMI.