Microvascular perfusion in infarcted and remote myocardium after successful primary PCI: angiographic and CMR findings.

OBJECTIVES: The aim of this study was to investigate the association between TIMI myocardial perfusion (TMP) grading acute and cardiac magnetic resonance (CMR) first-pass perfusion early and at 4 months in patients with ST-segment-elevation myocardial infarction (STEMI) treated with percutaneous coronary intervention (PCI). MATERIAL AND METHODS: One hundred ninety-eight STEMI patients were recruited from the POSTEMI study. TMP grade was assessed after PCI; CMR was performed at day 2 and after 4 months. Signal intensity was measured on first-pass perfusion images, and a maximum contrast enhancement index (MCE) was calculated. RESULTS: Patients with TMP grade 2-3 (n = 108) after PCI had significantly better EF (59 ± 10 vs. 51 ± 13, p < 0.001) and smaller infarct volume (12 ± 8 vs. 19 ± 12 %, p < 0.001) at 4 months compared with patients with TMP grade 0-1 (n = 81). MCE in the infarcted (MCEi) and remote myocardium (MCEr) improved from early to follow-up CMR, MCEi from 94 ± 56 to 126 ± 59, p < 0.001, and MCEr from 112 ± 51 to 127 ± 50, p < 0.001. In patients with the lowest CMR perfusion early, perfusion at 4 months remained decreased compared with the other groups, MCEi 108 ± 75 vs. 133 ± 51, p = 0.01, and MCEr 115 ± 41 vs. 131 ± 52, p = 0.047. CONCLUSION: TMP grade and early CMR first-pass perfusion were associated with CMR outcomes at 4 months. First-pass perfusion improved after 4 months in the infarcted and remote myocardium. However, in patients with the lowest CMR perfusion early, perfusion was still reduced after 4 months. KEY POINTS: • Cardiac magnetic resonance myocardial first-pass perfusion and TMP grading after successful PCI helps to assess risk in patients with ST elevation myocardial infarction. • Cardiac magnetic resonance myocardial first-pass perfusion shows that microvascular perfusion after ST elevation myocardial infarction can be impaired in both infarcted and non-infarcted myocardium. • Microvascular perfusion improves over time in patients with ST elevation myocardial infarction treated with primary PCI.