Temporal Evolution of Myocardial Hemorrhage and Edema in Patients After Acute ST‐Segment Elevation Myocardial Infarction: Pathophysiological Insights and Clinical Implications

Abstract

BackgroundThe time course and relationships of myocardial hemorrhage and edema in patients after acute ST‐segment elevation myocardial infarction (STEMI) are uncertain.Methods and ResultsPatients with ST‐segment elevation myocardial infarction treated by primary percutaneous coronary intervention underwent cardiac magnetic resonance imaging on 4 occasions: at 4 to 12 hours, 3 days, 10 days, and 7 months after reperfusion. Myocardial edema (native T2) and hemorrhage (T2*) were measured in regions of interest in remote and injured myocardium. Myocardial hemorrhage was taken to represent a hypointense infarct core with a T2* value <20 ms. Thirty patients with ST‐segment elevation myocardial infarction (mean age 54 years; 25 [83%] male) gave informed consent. Myocardial hemorrhage occurred in 7 (23%), 13 (43%), 11 (33%), and 4 (13%) patients at 4 to 12 hours, 3 days, 10 days, and 7 months, respectively, consistent with a unimodal pattern. The corresponding median amounts of myocardial hemorrhage (percentage of left ventricular mass) during the first 10 days after myocardial infarction were 2.7% (interquartile range [IQR] 0.0–5.6%), 7.0% (IQR 4.9–7.5%), and 4.1% (IQR 2.6–5.5%; P<0.001). Similar unimodal temporal patterns were observed for myocardial edema (percentage of left ventricular mass) in all patients (P=0.001) and for infarct zone edema (T2, in ms: 62.1 [SD 2.9], 64.4 [SD 4.9], 65.9 [SD 5.3]; P<0.001) in patients without myocardial hemorrhage. Alternatively, in patients with myocardial hemorrhage, infarct zone edema was reduced at day 3 (T2, in ms: 51.8 [SD 4.6]; P<0.001), depicting a bimodal pattern. Left ventricular end‐diastolic volume increased from baseline to 7 months in patients with myocardial hemorrhage (P=0.001) but not in patients without hemorrhage (P=0.377).ConclusionsThe temporal evolutions of myocardial hemorrhage and edema are unimodal, whereas infarct zone edema (T2 value) has a bimodal pattern. Myocardial hemorrhage is prognostically important and represents a target for therapeutic interventions that are designed to preserve vascular integrity following coronary reperfusion.Clinical Trial Registration URL: https://clinicaltrials.gov/. Unique identifier: NCT02072850.

Hyperaemic microvascular resistance predicts clinical outcome and microvascular injury after myocardial infarction

“…CMR was performed between 24 hours and 2 weeks (when MVI most frequently occurs23) after the index procedure and analysed by the local investigators. In brief, CMR cine images were acquired to calculate left ventricular end systolic and diastolic volumes and left ventricular ejection fraction.…”

Mapping Myocardial Salvage Index by Extracellular Volume Fraction

“…It is well recognized that acute MI size is dynamic, and acutely reduces in size within the first week, 11,12 and more chronically reduces over the first few months. 5,11 The regression in MI size represents the gradual resolution of myocardial edema, intramyocardial hemorrhage and MVO, and the gradual replacement of necrotic tissue with fibrosis in the chronic infarct.…”

Advances in Magnetic Resonance Imaging of the Myocardial Area at Risk and Salvage

“…2 Myocardial salvage is calculated by subtracting the infarct size on contrast-enhanced CMR from the myocardial area at risk, revealed by T1-or T2-weighted CMR, and predicts the likelihood of functional recovery. 2 On the contrary, edema imaging has limitations because the area at risk diminishes in size from ≈5 days post reperfusion, 3,4 and T2 relaxation times within the ischemic zone vary as infarct pathologies evolve. 5,6 Imaging Myocardial Edema Several CMR methods are now available for imaging myocardial edema 7 ; the most established of which is the T2-weighted short tau inversion recovery (T2-STIR) black blood technique.…”

“…We recognize the theoretical limitations of edema imaging, especially with T2-STIR. [4][5][6][7] The new applications with T1 mapping, T2 mapping, and CE-SSFP represent important advances, which strengthen the case for imaging the myocardial area at risk and salvage with CMR. Early post-MI the extent of edema (% LV mass) seems reasonably stable between days 3 to 10, 3,4 but in general evolves dynamically within the first 2 -3 days, [4][5][6] and falls progressively after the first week.…”