BACKGROUND AND AIMS:Intramyocardial hemorrhage (IMH) after reperfused ST-elevation myocardial infarction (STEMI) is associated with adverse outcomes, yet no therapy specifically targets it. Dexrazoxane (DXZ) may mitigate iron-mediated injury from IMH. METHODS:SHIELD-MI was a single-center, non-randomized, placebo-controlled, sequential-cohort phase IIa study with participants and the cardiac MRI (CMR) core laboratory blinded to treatment. Twenty-five patients received intravenous DXZ 250 mg before primary PCI and at 4, 8, and 12 h thereafter. Twenty-five comparators, selected from 78 placebo-treated patients, were matched on total ischemic time, culprit territory, and pre-PCI occlusion status. Primary endpoints were left ventricular ejection fraction (LVEF) and IMH volume on CMR at 48-72 h, evaluating early ventricular function and hemorrhagic myocardial injury after reperfusion. RESULTS:In the matched analytic cohort (n=50), LVEF was higher in patients receiving DXZ (39.8±7.7% vs. 34.7±10.1%; P=0.048), permitting formal testing of IMH volume, which was lower with DXZ (2.0±3.4% LV vs. 6.3±6.0% LV; P=0.004). The prespecified fixed-sequence criterion was therefore met at both steps. Infarct size was lower with DXZ (29.1±13.1% LV vs. 43.8±18.6% LV; P=0.002). Hemorrhagic MI occurred in 6/25 (24%) versus 16/25 (64%) participants (P=0.010). No drug-related serious adverse events were observed. CONCLUSIONS:Peri-procedural intravenous DXZ was associated with lower IMH and infarct size and higher LVEF, without safety concerns. These exploratory findings identify IMH as a candidate therapeutic target warranting a randomized trial.

Background:Staging irreversible tissue injury in myocardial infarction (MI) enables risk assessment for post-MI major cardiovascular events. While cardiac MRI is the preferred modality for staging the severity of tissue injury, conventional scan protocols require long acquisition times with multiple breath-held and ECG-gated acquisitions, limiting its utilization. Purpose:To develop a free-breathing, whole-heart, non-ECG gated cardiac MRI for staging irreversible tissue injury in MI that can be completed in <20 minutes. Materials and Methods:A fast cardiac MRI (Biograph, Siemens Healthcare, 3 T) method based on a low-rank tensor framework was developed (reconstruction performed in MATLAB) and tested against the conventional approach using a pre-clinical canine model of reperfused MI (n = 15) with histological validation. Each subject underwent 2 exams that were randomized 2 days apart (day 6-8 post MI, respectively). Correlations between the proposed and conventional methods and left-ventricular ejection fraction (LVEF), MI size and transmurality, size of microvascular obstruction (MVO), and intramyocardial hemorrhage (IMH) volumes were assessed using linear regression and Bland-Altman analysis. Results:Twelve out of 15 subjects survived the initial reperfusion injury. The proposed method reduced acquisition time by >50%. The cardiac MRI evidence of tissue injury was confirmed on histopathology in all cases. The agreements between the proposed and conventional methods for LVEF, MI volume, persistent MVO volume and IMH volume were excellent; limits of agreement (LoA) were -2.1%-1.8%, -2.9 % -3.3%, -2.4%-4.1%, and -1.5%-1.5%, respectively. MI transmurality and early MVO showed good agreement; LoA were -6.8%-9.7% and -6.6%-8.2%, respectively. Conclusion:The proposed free-breathing, whole-heart, non-ECG gated cardiac MRI approach permits accurate determination of tissue injury in a canine model with >2-fold reduction in scan time. While the method remains to be tested in patients, it has the potential to facilitate efficient use of cardiac MRI for staging the severity of tissue injury in patients with reperfused MI.

BACKGROUND:Intramyocardial hemorrhage (IMH) complicates approximately 40% of reperfused ST-segment elevation myocardial infarctions (STEMIs) and is associated with worse outcomes. No method identifies patients at risk before reperfusion. OBJECTIVES:The objective of the study was to develop and evaluate an explainable artificial intelligence approach for pre-reperfusion IMH prediction and translate it into a practical bedside score. METHODS:We enrolled 288 STEMI patients from the MIRON-PREDICT clinical study (NCT06423625) between June 2023 and December 2024, of whom 252 were used for model development and 36 were used for validation. Electrocardiographic, angiographic, and clinical variables were obtained during emergency coronary angiography. Cardiac magnetic resonance imaging 48 to 72 hours post-percutaneous coronary intervention served as the reference for IMH. A Superposable Neural Network identified key predictors and informed derivation of a point-based scoring model for bedside use. RESULTS:The final 3-variable model comprised the presence of coronary collaterals, degree of coronary artery occlusion, and sum ST-score. Cardiac magnetic resonance imaging identified IMH in 142/288 patients. Coronary collaterals were present in 144/288 and total occlusion in 131/288. Sum ST-score was substantially higher in IMH-positive than IMH-negative patients. The resulting model achieved 84.9% accuracy, 82.3% sensitivity, and 87.3% specificity in identifying patients at risk of IMH before reperfusion. This was confirmed in the validation cohort with 83.3% accuracy, 81.3% sensitivity, and 85% specificity. CONCLUSIONS:Explainable artificial intelligence enabled rapid integration of clinical parameters from cardiac catheterization procedures to accurately predict IMH in STEMI before revascularization. The proposed approach could guide clinical decisions in real-time. This could inform future strategies aimed at reducing the incidence of IMH.

BACKGROUND:Advances in acute ST-elevation myocardial infarction (STEMI) care have substantially decreased in-hospital mortality; however, in absolute terms, in-hospital mortality still remains high. Reperfusion injury, particularly intramyocardial hemorrhage following primary percutaneous coronary intervention (PCI), is a major predictor of adverse cardiovascular outcomes in the long term, but whether it contributes to in-hospital mortality is not known. METHODS:We performed a multicenter study to investigate the use of post-PCI high-sensitivity cardiac troponin I (hs-cTn-I) as a diagnostic tool to identify hemorrhagic myocardial infarction (MI) by determining hourly hs-cTn-I thresholds (every hour up to 12 hours, and at 16, 20, 24, and 48 hours post-PCI). We then investigated the relationship between patients classified as having hemorrhagic MI based on post-PCI hs-cTn-I cutoff values and in-hospital mortality using STEMI registries containing information about 6180 patients across seven hospitals in a single large health system in the United States. RESULTS:We enrolled 154 patients in a discovery cohort and 53 patients in a validation cohort. Hemorrhagic MI was diagnosed by cardiac magnetic resonance imaging. Post-PCI hs-cTn-I cutoff values for the determination of hemorrhagic MI were time dependent, with a sensitivity greater than 0.91, a specificity greater than 0.86, and an area under the curve (AUC) greater than 0.92 over the first 10 hours post-PCI, decreasing to a sensitivity greater than>0.84, a specificity greater than 0.80, and an AUC greater than 0.84 thereafter. The STEMI registry analysis demonstrated that patients classified as having hemorrhagic MI based on hs-cTn-I cutoff values had a 2.81-fold greater risk for in-hospital mortality than those classified as having had nonhemorrhagic MI (adjusted odds ratio, 2.81; 95% confidence interval, 2.17 to 3.64). CONCLUSIONS:Post-PCI troponin kinetics may have the potential to diagnose hemorrhagic MI, which was associated with in-hospital mortality. (Funded by the National Institutes of Health National Heart, Lung, and Blood Institute (grant numbers HL133407, HL136578, and HL147133) and others; ClinicalTrials.gov ID, NCT05872308).

Background: Intramyocardial hemorrhage (IMH), evident in 40% of revascularized ST-segment elevation myocardial infarction (STEMI) patients, is a lethal determinant of MI size. IMH compromises myocardial salvage and drives major adverse cardiovascular events. Objectives: We sought to determine whether the presence and extent of coronary collaterals affect development of IMH in STEMI patients. Methods: The MIRON-CL trial (NCT05898425) enrolled 294 consecutive STEMI patients reperfused via primary percutaneous coronary intervention (PCI). All underwent pre-PCI angiography to determine Rentrop collateral grades (0: none; III: complete). Three days post-PCI cardiac magnetic resonance imaging quantified myocardial area at risk (T2 edema), IMH (T2∗), and MI (late gadolinium enhancement). Results: Among 294 patients, 124 had IMH and 170 did not. Patients with no collaterals (CL−, Grade 0) had higher IMH (7.41% ± 5.33% left ventricle) than those with collaterals (CL+; Grade I: 5.23% ± 3.21%, II: 3.11% ± 2.78%, III: 2.05% ± 1.89%; P < 0.001). Total area at risk post-PCI was larger in CL− (37.62% ± 15.32% left ventricle) than in CL+ (21.48% ± 13.21%; P < 0.001). Absence of collaterals correlated with larger MI (CL− 38.66% ± 14.63% vs CL+ 19.84% ± 13.72%; P < 0.001) and higher microvascular obstruction (CL− 8.07% ± 6.60% vs CL+ 2.17% ± 2.35%; P < 0.001). Patients without collaterals had a higher adjusted risk of IMH (OR: 5.71; 95% CI: 3.16–10.33; P < 0.0001). Conclusions: Extent of coronary collaterals is a determinant of IMH in revascularized STEMI. Since IMH is known to drive post-PCI infarct expansion, determination of collateral status has the potential to identify patients at high risk of infarct expansion. For these high-risk patients, novel targeted therapies to reduce IMH, limit post-MI infarct expansion, and improve outcomes should be further explored.

The Canadian Cardiovascular Society recently put forth a new classification of acute reperfused myocardial infarction (MI) based on stages of myocardial injury. Backed by more than 5 decades of intense investigation in the field, the key message of this new classification is that not all MIs are the same and that the type and extent of myocardial injury should be considered in diagnosing and treating MI. We review the literature with the goal of highlighting the progressive advances that enabled the synthesis of the Canadian Cardiovascular Society classification into 4 distinct stages of tissue injury. We emphasize the major breakthroughs from insights gained from experimental, translational, and clinical studies to date. We also identify current gaps in knowledge and critical research directions that need to be pursued to improve patient care and reduce post-MI complications such as chronic heart failure and malignant arrhythmias, whose risk is linked to stage and extent of myocardial injury.

We report a case of intracardiac cement embolism in a 24-year-old male patient as a rare postprocedural complication of percutaneous vertebroplasty. The patient was assessed 1 month after the procedure because of persistent tachycardia. Computed tomography scans showed an intracardiac mass in both the right atrium and right ventricle. After thorough multidisciplinary discussion, the patient was subsequently managed conservatively in conjunction with serial imaging and close surveillance.

We report a case of intracardiac cement embolism in a twenty-four year old male as a rare post-procedural complication of percutaneous vertebroplasty. The patient was assessed one month after the procedure because of persistent tachycardia. Computed tomography scans showed an intracardiac mass in both the right atrium and right ventricle. After thorough multidisciplinary discussion, the patient was subsequently managed conservatively in conjunction with serial imaging and close surveillance.