Morphologic Validation of Reperfused Hemorrhagic Myocardial Infarction by Cardiovascular Magnetic Resonance

Abstract

The purposes of this study were to assess the ex vivo cardiovascular magnetic resonance (CMR) signals of pathologically proved hemorrhagic myocardial infarction (MI) and to correlate these with in vivo CMR findings. Late gadolinium hypoenhancement within a hyperenhanced area in reperfused acute MI is ascribed to severe microvascular obstruction. The hearts of 2 patients, who died from cardiogenic shock after acute MIs and who had undergone coronary recanalization and in vivo CMR, were examined by T(2) and T(1) late enhancement sequences as well as by gross and histologic investigation. Four corresponding short-axis slices of each cardiac specimen from the base to the left ventricular apex were selected to assess the extent of MI and hemorrhage and were compared with the in vivo T(2) and late enhancement CMR scans. On pathologic examination, the extent of MI was 57 +/- 30% and 44 +/- 24%, and the extent of hemorrhage was 23 +/- 13% and 19 +/- 8% of the left ventricular area, respectively, showing progressive increases from the base to the apex. The low-signal intensity areas observed by ex vivo T(2) CMR strongly correlated with the hemorrhage quantified on histology (R = 0.93, p = 0.0007). Using ex vivo late gadolinium sequences, bright areas surrounded by thin dark rims, consistent with magnetic susceptibility effects, were detected, corresponding with hemorrhage. On in vivo CMR images, low-signal intensity and hyperintense areas with peripheral susceptibility artifacts were observed within the MI core on T(2) and late gadolinium sequences, respectively. In conclusion, in reperfused MI, CMR hypointense T(2) signal and susceptibility effects within the late gadolinium hypoenhanced areas are consistent with interstitial hemorrhage due to irreversible vascular injury, as proved by pathologic study.