Abstract
BACKGROUND: Hemorrhagic myocardial infarction (hMI) can rapidly diminish the benefits of reperfusion therapy and direct the heart toward chronic heart failure. T2∗ cardiac magnetic resonance (CMR) is the reference standard for detecting hMI. However, the lack of clarity around the earliest time point for detection, time-dependent changes in hemorrhage volume, and the optimal methods for detection can limit the development of strategies to manage hMI. OBJECTIVES: The authors investigated CMR signal characteristics of hMI through time-lapse multiparametric mapping using a clinically relevant animal model and evaluated the translatability in ST-segment elevation MI patients when possible. METHODS: Canines (N = 20) underwent 3.0-T CMR at baseline and various time points over the first week of reperfused MI. Time-dependent relationships between T1, T2, and T2∗ mapping of hMI, non-hMI, and remote territories were determined. Reperfused ST-segment elevation MI patients (N = 50) were studied to establish clinically feasibility. RESULTS: Although hMI was evident <1 hour after reperfusion on histopathology, it was not reliably detected with T1, T2, or T2∗ CMR. However, 24 hours to 7 days postreperfusion, hMI was detectable on T2∗ (27.0 ± 2.4 ms [baseline] vs 11.7 ± 2.8 ms [hMI]; P < 0.001), with stable volume and transmurality. In T2 maps, hMI was most visible 5 to 7 days postreperfusion with an area under the curve of 0.98 (sensitivity and specificity ≥0.95) relative to T2∗. However, this was not the case with T1 (sensitivity <0.8, across all time points). CONCLUSIONS: HMI cannot be reliably detected with T1, T2, or T2∗ on 3.0-T CMR immediately after reperfusion. However, T2∗ CMR can be used to diagnose hMI between 24 hours and 7 days postreperfusion. T2 maps at 3.0-T are a strong alternative to T2∗ maps for diagnosing hMI, provided CMR is performed 5 to 7 days postreperfusion. However, diagnosing hMI with T1 is significantly more challenging at 3.0-T compared with both T2∗ and T2.