Relationship of cardiac biomarkers and reversible and irreversible myocardial injury following acute myocardial infarction as determined by cardiovascular magnetic resonance.

Background: Cardiovascular magnetic resonance (CMR) can accurately depict myocardial oedema, haemorrhage, infarction and microvascular obstruction. The purpose of this study was to establish the relationships between cardiac biomarkers and reversible and irreversible myocardial injury following AMI, as determined by CMR.
Methods: Forty-eight patients admitted with AMI and successfully treated with primary percutaneous coronary intervention were studied. A comprehensive CMR protocol was performed at day 2, 1 week, 1 month and 3 months after presentation. Blood samples were taken at the same intervals and analysed for highly sensitive C-reactive protein (hs-CRP), Troponin I, N-terminal-pro-brain natriuretic peptide (NT-pro-BNP) and Heart-type fatty acid binding protein (H-FABP). The CMR end points were the extent of myocardial oedema, haemorrhage and infarction as well as left ventricular function and volumes.
Results: Multiple regression analyses demonstrated that hs-CRP on 'day 2' was the strongest independent predictor of left ventricular ejection fraction (LVEF) (p=0.007) and left ventricular end-systolic volume (LVESV) (p=0.002) at 3 months. Troponin I level on 'day 2' was the only independent predictor of infarct size (p=0.002) at 3 months. Patients with haemorrhagic infarctions had significantly higher biomarker levels at 'day 2'. NT-pro-BNP levels were significantly greater in patients with myocardial haemorrhage at all four time points.
Conclusions: C-reactive protein measured two days after reperfusion was the strongest independent predictor of left ventricular remodelling at three months. Elevated biomarker levels in patients with haemorrhagic infarction suggest that reperfusion haemorrhage is a marker of more severe myocardial injury and may be associated with adverse ventricular remodelling.
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