Temporal course of microvascular obstruction after myocardial infarction assessed by MRI.

Purpose: We aimed to analyze the extent of microvascular obstruction (MO) after the index event compared with the follow-up at a median of three months.

Methods: We identified 31 patients with MO after primary percutaneous coronary intervention of acute myocardial infarction by cardiac magnetic resonance imaging. The initial examination was performed after the index event, and 27 patients had the follow-up exam after a median of three months (interquartile range, 2-4 months). In addition, we examined 10 patients without MO after transmural myocardial infarction, as a control group.

Results: MO disappeared in 23 of 27 patients (85%) in the follow-up and transformed into transmural late gadolinium enhancement. In patients with persistent MO, mean MO size decreased from 2.25% to 1.25%. In patients with MO, mean infarct size decreased significantly from 20.8% to 14.7% (P < 0.001). In the control group, mean infarct size decreased from 12.7% to 10.5% in the follow-up scan (P = 0.137).

Conclusion: MO is significantly reduced during the follow-up after acute myocardial infarction.