# Time to Reperfusion Dictates Cardiac Function and Myocardial Strain in a 7-Tesla Magnetic Resonance Imaging Rat Model

## TL;DR

This study shows that the time to reperfusion after a heart attack affects heart function and muscle strain in rats, using high-resolution MRI.

## Contribution

The study demonstrates that radial strain detected early myocardial changes, while longitudinal strain reflects compensatory mechanisms in severe infarction.

## Key findings

- Radial strain decreased significantly between control and 20 min infarction groups.
- 30 and 40 min infarction groups showed significant reductions in cardiac function and strain compared to controls.
- Longitudinal strain showed no significant difference between 30 and 40 min infarction groups.

## Abstract

This study used a rat model of coronary artery reperfusion imaged with preclinical 7-tesla magnetic resonance imaging (7T-MRI) to evaluate cardiac function, myocardial deformation, and the impact of infarction-to-reperfusion time. Wistar rats were assigned to control (n = 6), 20 min infarction (n = 10), 30 min infarction (n = 6), and 40 min infarction (n = 6) groups. Myocardial infarction occurred in all infarction groups but not in controls. Imaging included short- and long-axis slices. Cardiac function was assessed using end-diastolic volume, end-systolic volume, and left-ventricular ejection fraction. Myocardial deformation was analyzed by circumferential strain, radial strain (RS), and longitudinal strain (LS, four-chamber and two-chamber) using feature tracking. The 30 and 40 min infarction groups showed significant reductions in cardiac function and strain compared to the controls. RS decreased significantly between the control and 20 min infarction groups (40.6 ± 4.7% and 34.0 ± 4.1%, p < 0.05). No significant LS difference was observed between 30 and 40 min. Consequently, RS detects early myocardial changes (20 min), whereas LS may reflect compensatory contractility in severe infarction. Preclinical 7T-MRI provides valuable insights into the impact of infarction duration on cardiac function and myocardial deformation.