The severity of post-infarction edema suggests a bimodal pattern, whereas the extent does not.

BACKGROUND

Preclinical and clinical data following acute myocardial infarction (MI) have shown conflicting results whether a bimodal pattern of edematous myocardium at risk (MaR) on cardiovascular magnetic resonance (CMR) imaging during the first week exists or not. The objective was to assess the dynamics of MaR following acute experimental MI using a comprehensive CMR protocol.

METHODS

Acute MI was induced in seven pigs with reperfusion after 40 min. CMR was performed at baseline, 120 min, 24 h and 7 days post reperfusion. The CMR protocol comprised two T2-mapping sequences, a T2-SSFP sequence (T2-mappingSSFP) and a T2-TSE sequence (T2-mappingTSE), as well as a T2w short-tau inversion recovery (T2-STIR) sequence. After contrast administration, CE-SSFP and LGE images were acquired. The severity of MaR was defined as the T2 relaxation on T2 maps and the extent of MaR as percentage of edematous myocardium on CE-SSFP and T2-STIR images.

RESULTS

The severity of edema within the MaR was significantly lower at 24 h compared to 120 min (T2 mappingSSFP:69±9 vs 80±8 ms; T2 mappingTSE:57±7 vs 69±9 ms), followed by a recovery at 7 days (T2 mappingSSFP:77±10 ms; T2 mappingTSE:67±12 ms). The extent of MaR showed a gradual decrease between 120 min and 24 h on CE-SSFP (29±10 vs 26±9%LVM) and at 7 days compared to both previous time points (CE-SSFP: 24±11%LVM).

CONCLUSION

The severity of edema within the MaR following acute MI suggests a bimodal pattern, whereas the extent of MaR does not.