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.

MR findings of microvascular perfusion in infarcted and remote myocardium early after successful primary PCI.

OBJECTIVES: The aim of the study was to evaluate CMR myocardial first-pass perfusion in the injured region as well as the non-infarcted area in ST-elevation myocardial infarction (STEMI) patients few days after successful primary percutaneous coronary intervention (PCI). MATERIALS AND METHODS: 220 patients with first time STEMI successfully treated with PCI (with or without postconditioning) were recruited from the Postconditioning in STEMI study. Contrast enhanced CMR was performed at a 1.5 T scanner 2 (1-5) days after PCI. On myocardial first-pass perfusion imaging signal intensity (SI) was measured in the injured area and in the remote myocardium and maximum contrast enhancement index (MCE) was calculated. MCE = (peak SI after contrast-SI at baseline) / SI at baseline x 100. RESULTS: There were no significant differences in first-pass perfusion between patients treated with standard PCI and patients treated with additional postconditioning. The injured myocardium showed a significantly lower MCE compared to remote myocardium (94 ± 55 vs. 113 ± 49; p < 0.001). When patients were divided into four quartiles of MCE in the injured myocardium (MCE injured myocardium), patients with low MCE injured myocardium had: significantly lower ejection fraction (EF) than patients with high MCE injured myocardium, larger infarct size and area at risk, smaller myocardial salvage and more frequent occurrence of microvascular obstruction on late gadolinium enhancement. MCE in the remote myocardium revealed that patients with larger infarction also had significantly decreased MCE in the non-infarcted, remote area. CONCLUSION: CMR first-pass perfusion can be impaired in both injured and remote myocardium in STEMI patients treated with primary PCI. These findings indicate that CMR first-pass perfusion may be a feasible method to evaluate myocardial injury after STEMI in addition to conventional CMR parameters.