Microvascular obstruction assessed by 3-tesla magnetic resonance imaging in acute myocardial infarction is correlated with plasma troponin I levels.

Background: Microvascular obstruction (MVO) at the acute phase of myocardial infarction (MI) is associated with poor prognosis. We aimed to evaluate the correlation between plasma cardiac troponin I (cTnI) at the acute phase of MI and extent of no-reflow, as assessed by 3-T cardiac magnetic resonance imaging (MRI). Secondly, we defined a cut-off value for cTnI predictive of no-reflow.

Methods: 51 consecutive patients with no previous history of cardiovascular disease, presenting ST elevation MI within <12 h. Infarct size and extent of no-reflow were evaluated by 3-T MRI at day 5. Extent of no-reflow at 15 minutes (MVO) was correlated with cTnI at admission, 6, 12, 24, 48 and 72 hours. At 6 months, MRI was performed to evaluate the impact of MVO on LV remodeling.

Results: MVO was diagnosed in 29 patients (57%). Extent of MVO was significantly correlated to peak troponin, cTnI (except admission values) and area under the curve. Using Receiver-operating characteristic (ROC) curve analysis, a cut-off cTnI value >89 ng/mL at 12 h seemed to best predict presence of early MVO (sensitivity 63%, specificity 88%). At 6 months, MVO was associated with left ventricular (LV) remodeling, resulting in higher LV volumes.

Conclusion: There is a relationship between cTnI at the acute phase of AMI and extent of MVO as assessed by 3-T cardiac MRI. A cut-off cTnI value of 89 ng/mL at 12 h seems to best predict presence of MVO, which contributes to LV remodeling.