Key result
Abnormal microvascular perfusion drops ~46% six months post-MI, with chronic hypoperfusion linked to worse systolic function.
Cohort (n=40)
Single-blind
No
Absolute Event Rate: 14% vs 26%
p-value: p=<0.0001
First-pass perfusion CMR demonstrates that while most hypoperfused myocardial segments normalize by 6 months post-STEMI, chronic abnormal perfusion persists in a minority and is associated with worse myocardial function and greater transmural necrosis.
May flag high-risk segments for closer post-STEMI surveillance; leaves open whether microvascular-targeted therapies improve outcomes.
OBJECTIVE: To characterise the evolution of myocardial perfusion during the first 6 months after myocardial infarction by first-pass perfusion cardiovascular magnetic resonance imaging (CMR) and determine its significance. DESIGN: Prospective cohort design. SETTING: Single-centre study in a teaching hospital in Spain. PATIENTS: 40 patients with a first ST-elevation myocardial infarction, single-vessel disease and thrombolysis in myocardial infarction (TIMI) grade 3 flow (stent in 33 patients) underwent rest and low-dose dobutamine CMR 7 (SD 1) and 184 (SD 11) days after infarction. Microvascular perfusion was assessed at rest by visual assessment and quantitative analysis of first-pass perfusion CMR. Of the 640 segments, 290 segments subtended by the infarct-related artery (IRA) were focused on. RESULTS: Both 1 week and 6 months after infarction, segments with normal perfusion showed more wall thickening, contractile reserve and wall thickness, and less transmural necrosis, p <0.05 in all cases. Of 76 hypoperfused segments at the first week, 47 (62%) normalised perfusion at the sixth month. However, 42 segments (14% of the whole group) showed chronic abnormal perfusion; these segments showed worse CMR indices in the late phase (p<0.05 in all cases). CONCLUSIONS: In patients with an open IRA, more than half of the segments with abnormal perfusion at the first week are normally perfused after six months. First-pass perfusion CMR shows that in a small percentage of segments, abnormal perfusion may become a chronic phenomenon-these areas have a more severe deterioration of systolic function, wall thickness, contractile reserve and the transmural extent of necrosis.
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Bodı́ et al. (2006) conducted a cohort in first ST-elevation myocardial infarction (n=40). Time after myocardial infarction (6 months) vs. 1 week post-infarction was evaluated on Abnormal microvascular perfusion in segments subtended by the infarct-related artery (p=<0.0001). In patients with an open infarct-related artery, the proportion of segments with abnormal microvascular perfusion decreased from 26% at 1 week to 14% at 6 months, with chronically hypoperfused segments showing worse systolic function.
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