Cardiac MRI of differing ischemia and reperfusion times in a myocardial infarction pig model

Fig. 1. Induction of myocardial ischemia reperfusion injury. (A) Interventional setup with an angiography x-ray system for catheter-based balloon occlusion of a coronary artery. (B) Coronary angiogram showing the left coronary artery (highlighted in red) with the LAD occluded downstream of the origin of the first ramus diagonalis (RD). The estimated position of the balloon for an LCX occlusion is indicated by “*”. (C) Typical progressive ECG changes during LAD occlusion: In the initial pre-ischemic state, a sinus rhythm without signs of ischemia. Within the first 5–10 min of ischemia, ST-segment elevations > 0.1 mV and reciprocal depressions emerge, becoming progressively more pronounced over time. Ventricular ectopic beats frequently appear after approximately 30 min of ischemia. Immediately following reperfusion, pronounced T-wave changes are evident.

Fig. 2. Experimental design. (A) Blue symbols represent pigs that underwent MRI 2–5 h post MI-induction. (B) Red symbols represent pigs that underwent MRI three days post MI-induction. (C) Representative placement of the LCX and LAD ROIs.

Fig. 3. Time to VF during coronary occlusion. The Kaplan–Meier curve (19 pigs) illustrating the time to first occurrence of VF during coronary occlusion. Red censor marks indicate pigs where ischemia was terminated before VF occurred. VF before or after coronary occlusion isn’t displayed.

Fig. 4. Representative T1 map (left), T2 map (middle) and LGE (right) images. (A–C) CMR images acquired 2–5 h after a 37 min LAD occlusion. (D–F) CMR images acquired three days after a 45 min LCX occlusion. (G–I) CMR images acquired three days after a 60 min LAD occlusion. (J–L) CMR images acquired three days after 90 min LAD occlusion.

Fig. 5. LVEF, wall motion alteration. (A): Overall mean EF measured post-ischemia was 51.7 ± 10%. The EF following short ischemia was significantly lower compared to long ischemia. The EF measured 2–5 h post-ischemia was significantly lower compared to three days post-ischemia. The dashed line indicates the EF in healthy pigs of similar age and breed55. (B) Wall motion alterations observed post-ischemia.

Fig. 6. T1 & T2 mapping results. (A) T1 values of ischemic myocardium compared to remote myocardium. (B) T1 for different infarct durations with linear regression. (C) T1 grouped for different infarct durations considering all animals. (D T1 grouped for different infarct durations considering only the five animals with MRI three days post-MI. (E) T2 values of ischemic myocardium compared to remote myocardium. (F) T2 for different infarct durations with linear regression. (G) T2 grouped for different infarct durations considering all animals. (H) T2 for different infarct durations considering only the five animals with MRI three days post-MI. ‘Ns’ denotes p ≥ 0.05; *p < 0.05, **p < 0.01, ***p < 0.001.