T2* cardiac MRI allows prediction of severe reperfusion injury after STEMI
MedWire News: T2*-weighted cardiac MRI (T2*-CMR) may identify ST-elevation myocardial infarction (STEMI) patients who are at increased risk for severe reperfusion injury after successful revascularization by percutaneous coronary intervention (PCI), researchers suggest.
This reperfusion injury risk is greater when the infarct is near-transmural, which indicates "that once advanced necrosis has developed, the potential for severe myocardial reperfusion injury is significantly enhanced," say Declan O'Regan (Imperial College, London, UK) and colleagues.
To determine visually identifiable predictors of acute ischemia-reperfusion injury, O'Regan and colleagues recruited 50 STEMI patients.
The team performed T2*-CMR on the patients 1-7 days after PCI. All patients were successfully revascularized, with a mean symptom-to-reperfusion time of 3.9 hours.
Writing in the journal Heart, O'Regan and team report that both microvascular obstruction (MVO) and focal hemorrhagic ischemic reperfusion injury were detected by T2*-CMR in the same 29 patients (58%).
An area of hemorrhage was only detected in patients with an infarct that involved 80% or more of the depth of the left ventricular wall, and a greater mean infarct volume was more often associated with the presence of hemorrhage compared with its absence, at 23.8% versus 12.0% (p<0.0001).
Furthermore, a strong correlation was identified between the area of MVO and the area of hemorrhage (p<0.001). However, this correlation grew weaker when the area of MVO was large and variable (p<0.003).
O'Regan and colleagues explain: "Ischemic-reperfusion injury is known to have a major influence on myocyte salvage and final infarct size.
"Our study has used a novel imaging technique to quantify the presence of myocardial hemorrhage which is indicative of severe reperfusion injury in post-STEMI patients."
They conclude: "As well as risk stratification, T2*-CMR may also prove useful in the investigation of cardioprotective therapies by providing a specific biomarker of reperfusion-induced tissue injury."
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By Lauretta Ihonor