1024 A novel CMR-based myocardial salvage index predicts left ventricular remodeling after acute myocardial infarction: insights from T2-weighted and late gadolinium enhancement imaging

Background

Late gadolinium enhancement (LGE) accurately identifies irreversible injury after acute myocardial infarction (AMI). T2-weighted imaging has the ability to quantify the area at risk in the same setting. We investigated the value of a novel myocardial salvage index based on the difference between the extents of T2-weighted abnormality and LGE to predict long-term left ventricular remodeling after AMI.

Methods

We enrolled 41 patients (31 males, 56 ± 11 y) 3 ± 2 days after successful infarct reperfusion by PCI. Thirty-five patients returned for follow up 15 ± 13 months (median 12 months) after the acute event. The CMR protocol consisted of cine steady state free precession, triple inversion recovery T2-weighted and late gadolinium enhancement imaging (10 minutes after the iv injection of gadolinium-DTPA). Left ventricular volumes and function were quantified independent from the tissue characterization analysis and by different observers. In the acute phase, T2-weighted and LGE images were analyzed by special software (CMR42^R, CIRCLE, Calgary) to quantify volumes of abnormal signal, which were expressed as a percent of the total LV volume. The difference between T2 and LGE extents (T2-LGE) was then calculated as a measure of myocardial salvage. The primary end-points were the change in end-diastolic volume (delta-EDV) and end-systolic volume (delta-ESV) over time.

Results

T2-weighted abnormalities were detected only during the acute phase. T2-LGE but not LGE alone (p = 0.1) correlated with the time to reperfusion (r = -0.39; p = 0.014). Both T2-LGE (r = -0.52; p = 0.002) and LGE alone (r = 0.41; p = 0.018) correlated with delta EDV. T2-LGE correlated with delta-ESV (r = -0.39, p = 0.026) but LGE alone did not (p = 0.43).

The relation between T2-LGE, delta EDV and delta-ESV remained significant after correcting for the inter-study duration, time to reperfusion, ejection fraction and LGE extent.

Conclusion

We propose a myocardial salvage index based on the difference between T2-weighted abnormality and late gadolinium enhancement. This novel CMR-based parameter may have the potential to serve as a surrogate end-point in studies assessing the efficacy of infarct reperfusion strategies.