Clinical implications of microvascular obstruction and intramyocardial haemorrhage in acute myocardial infarction using cardiovascular magnetic resonance imaging.

Objectives: To investigate the clinical implications of microvascular obstruction (MVO) and intramyocardial haemorrhage (IMH) in acute myocardial infarction (AMI).
Methods: Ninety patients with a first AMI undergoing primary percutaneous coronary intervention (PCI) were studied. T2-weighted, cine and late gadolinium-enhanced cardiovascular magnetic resonance imaging was performed at 5 ± 2 and 103 ± 11 days. Patients were categorised into three groups based on the presence or absence of MVO and IMH.
Results: MVO was observed in 54% and IMH in 43% of patients, and correlated significantly (r = 0.8, p < 0.001). Pre-PCI thrombolysis in myocardial infarction 3 flow was only observed in MVO(-)/IMH(-) patients. Infarct size and impairment of systolic function were largest in MVO(+)/IMH(+) patients (n = 39, 23 ± 9% and 47 ± 7%), smallest in MVO(-)/IMH(-) patients (n = 41, 8 ± 8% and 55 ± 8%) and intermediate in MVO(+)/IMH(-) patients (n = 10, 16 ± 7% and 51 ± 6%, p < 0.001). LVEF increased in all three subgroups at follow-up, but remained intermediate in MVO(+)/IMH(-) and was lowest in MVO(+)/IMH(+) patients. Using random intercept model analysis, only infarct size was an independent predictor for adverse LV remodelling.
Conclusions: Intramyocardial haemorrhage and microvascular obstruction are strongly related. Pre-PCI TIMI 3 flow is less frequently observed in patients with MVO and IMH. Only infarct size was an independent predictor of LV remodelling.