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Aims: \ud Identifying novel mediators of lethal myocardial reperfusion injury that can be targeted during primary percutaneous coronary intervention (PPCI) is key to limiting the progression of patients with ST-elevated myocardial infarction (STEMI) to heart failure. Here we show through parallel clinical and integrative preclinical studies the significance of the protease cathepsin-L on cardiac function during reperfusion injury.\ud \ud Methods and Results: \ud We found that direct cardiac release of cathepsin-L in STEMI patients (n = 76) immediately post-PPCI leads to elevated serum cathepsin-L levels and that serum levels of cathepsin-L in the first 24 hour post-reperfusion are associated with reduced cardiac contractile function and increased infarct size. Preclinical studies, demonstrate that inhibition of cathepsin-L release following reperfusion injury with CAA0225 reduces infarct size and improves cardiac contractile function by limiting abnormal cardiomyocyte calcium handling and apoptosis.\ud \ud Conclusion: \ud Our findings suggest that cathepsin-L is a novel therapeutic target that could be exploited clinically to counteract the deleterious effects of acute reperfusion injury after an acute STEMI.\ud \ud Translational perspective: \ud New therapeutic targets are urgently required to limit myocardial damage after reperfusion injury. We identified cardiac release of the protease cathepsin-L among patients following primary percutaneous coronary intervention (PPCI). Elevated serum levels of cathepsin-L were associated with reduced contractile function and increased infarct size at 24 hour and 6 months post-PPCI. Work conducted using animal models indicated that cardiac release of cathepsin-L mediated cardiac dysfunction following reperfusion injury. Specific inhibition of cathepsin-L prevented abnormal calcium handling, reduced infarct size and improved contractile function. These novel findings offer the prospect of targeting cathepsin-L-mediated cardiac dysfunction after PPCI.

BACKGROUND Novel parameters that detect failed microvascular reperfusion might identify better the patients likely to benefit from adjunctive treatments during primary percutaneous coronary intervention (PCI). AIMS The aim of this study was to test the hypothesis that a novel invasive parameter, the thermodilution-derived temperature recovery time (TRT), would be associated with microvascular obstruction (MVO) and prognosis. METHODS TRT was derived and validated in two independent ST-elevation myocardial infarction populations and was measured immediately post PCI. TRT was defined as the duration (seconds) from the nadir of the hyperaemic thermodilution curve to 20% from baseline body temperature. MVO extent (% left ventricular mass) was assessed by cardiovascular magnetic resonance imaging at 2-7 days. RESULTS In the retrospective derivation cohort (n=271, mean age 60±12 years, 72% male), higher TRT was associated with more MVO (coefficient: 4.09 [95% CI: 2.70-5.48], p 32, CFR ≤2, hyperaemic Tmn >median, thermodilution waveform, age and ischaemic time. At five years, higher TRT was multivariably associated with all-cause death/heart failure hospitalisation (OR 4.14 [95% CI: 2.08-8.25], p

Coronary perforation is a potentially life-threatening complication of percutaneous coronary intervention (PCI). We studied incidence, outcomes and temporal trends following PCI-related coronary artery perforation (CAP).MethodsProspective systematic review and meta-analysis including meta-regression using MEDLINE and EMBASE to November 2020. We included ‘all-comer’ PCI cohorts including large PCI registries and randomised controlled trials and excluding registries or trials limited to PCI in high-risk populations such as chronic total occlusion PCI or cohorts treated only with atheroablative devices. Regression analysis and corresponding correlation coefficients were performed comparing perforation incidence, mortality rate, tamponade rate and the rate of Ellis III perforations against the midpoint (year) of data collection to determine if a significant temporal relationship was present.Results3997 studies were screened for inclusion. 67 studies met eligibility criteria with a total of 5 568 191 PCIs included over a 38-year period (1982–2020). The overall pooled incidence of perforation was 0.39% (95% CI 0.34% to 0.45%) and remained similar throughout the study period. Around 1 in 5 coronary perforations led to tamponade (21.1%). Ellis III perforations are increasing in frequency and account for 43% of all perforations. Perforation mortality has trended lower over the years (7.5%; 95% CI 6.7% to 8.4%). Perforation risk factors derived using meta-regression were female sex, hypertension, chronic kidney disease and previous coronary bypass grafting. Coronary perforation was most frequently caused by distal wire exit (37%) followed by balloon dilation catheters (28%). Covered stents were used to treat 25% of perforations, with emergency cardiac surgery needed in 17%.ConclusionCoronary perforation complicates approximately 1 in 250 PCIs. Ellis III perforations are increasing in incidence although it is unclear whether this is due to reporting bias. Despite this, the overall perforation mortality rate (7.5%) has trended lower in recent years. Limitations of our findings include bias that may be introduced through analysis of multidesign studies and registries without pre-specified standardised perforation reporting CMore research into coronary perforation management including the optimal use of covered stents seems warranted.PROSPERO registration numberCRD42020207881.

OBJECTIVES: This study compared the prognostic value of a noncontrast CMR risk score for the composite of all-cause death, nonfatal myocardial infarction, and new congestive heart failure.BACKGROUND: A cardiovascular magnetic resonance (CMR) risk score including left ventricular ejection fraction (LVEF), myocardial infarct (MI) size, and microvascular obstruction (MVO) was recently proposed to risk-stratify patients with ST-segment elevation myocardial infarction (STEMI).METHODS: The Eitel CMR risk score and GRACE (Global Registry of Acute Coronary Events) score were used as a reference (Score 1: acute MI size ≥19% LV, LVEF ≤47%, MVO >1.4% LV and GRACE score). MVO was replaced by intramyocardial hemorrhage (IMH) in Score 2 (acute MI size ≥19% LV, LVEF ≤47%, IMH, and GRACE score). Score 3 included only LVEF ≤45%, IMH, and GRACE score.RESULTS: There were 370 patients in the derivation cohort and 234 patients in the validation cohort. In the derivation cohort, the 3 scores performed similarly and better than GRACE score to predict the 1-year composite endpoint with C-statistics of 0.83, 0.83, 0.82, and 0.74, respectively. In the validation cohort, there was good discrimination and calibration of score 3, with a C-statistic of 0.87 and P = 0.71 in a Hosmer-Lemeshow test for goodness of fit, on the 1-year composite outcome. Kaplan-Meier curves for 5-year composite outcome showed that those with LVEF ≤45% (high-risk) and LVEF >45% and IMH (intermediate-risk) had significantly higher cumulative events than those with LVEF >45% and no IMH (low-risk), log-rank tests: P = 0.02 and P = 0.03, respectively. The HR for the high-risk group was 2.3 (95% CI: 1.1-4.7) and for the intermediate-risk group was 2.0 (95% CI: 1.0-3.8), and these remained significant after adjusting for the GRACE score.CONCLUSIONS: This noncontrast CMR risk score has performance comparable to an established risk score, and patients with STEMI could be stratified into low risk (LVEF >45% and no IMH), intermediate risk (LVEF >45% and IMH), and high risk (LVEF ≤45%). (A Trial of Low-dose Adjunctive alTeplase During prIMary PCI [T-TIME]; NCT02257294) (Detection and Significance of Heart Injury in ST Elevation Myocardial Infarction [BHF MR-MI]; NCT02072850).

BackgroundWe investigated the associations of healthcare worker status with multisystem illness trajectory in hospitalised post-COVID-19 individuals.Methods and resultsOne hundred and sixty-eight patients were evaluated 28–60 days after the last episode of hospital care. Thirty-six (21%) were healthcare workers. Compared with non-healthcare workers, healthcare workers were of similar age (51.3 (8.7) years vs 55.0 (12.4) years; p=0.09) more often women (26 (72%) vs 48 (38%); pIn adjusted multivariate logistic regression analysis, healthcare worker status associated with a binary classification (probable/very likely vs not present/unlikely) of adjudicated myocarditis (OR: 2.99; 95% CI (1.01 to 8.89) by 28–60 days postdischarge).After a mean (SD, range) duration of follow-up after hospital discharge of 450 (88) days (range 290, 627 days), fewer healthcare workers died or were rehospitalised (1 (3%) vs 22 (17%); p=0.038) and secondary care referrals for post-COVID-19 syndrome were common (42%) and similar to non-healthcare workers (38%; p=0.934).ConclusionHealthcare worker status was independently associated with the likelihood of adjudicated myocarditis, despite better antecedent health. Two in five healthcare workers had a secondary care referral for post-COVID-19 syndrome.Trial registration numberNCT04403607.

Background: The pathophysiology and trajectory of multiorgan involvement in post-COVID-19 syndrome is uncertain. Methods: A prospective, multicenter, longitudinal, cohort study involving post-COVID-19 patients enrolled in-hospital or early post-discharge (visit 1) and re-evaluated 28-60 days post-discharge (visit 2). Multisystem investigations included chest computed tomography with pulmonary and coronary angiography, cardiovascular and renal magnetic resonance imaging, digital electrocardiography, and multisystem biomarkers. The primary outcome was the adjudicated likelihood of myocarditis.Results: 161 patients (mean age 55 years, 43% female) and 27 controls with similar age, sex, ethnicity, and vascular risk factors were enrolled from 22 May 2020 to 2 July 2021 and had a primary outcome evaluation. Compared to controls, at 28-60 days post-discharge, patients with COVID-19 had persisting evidence of cardio-renal involvement, systemic inflammation, and hemostasis pathway activation. Myocarditis was adjudicated as being not likely (n=17; 10%), unlikely (n=56; 35%), probable (n=67; 42%) or very likely (n=21; 13%). Acute kidney injury (odds ratio, 95% confidence interval: 3.40 (1.13, 11.84); p=0.038) and low hemoglobin A1c (0.26 (0.07, 0.87); p=0.035) were multivariable associates of adjudicated myocarditis. During convalescence, compared to controls, COVID-19 was associated with worse health-related quality of life (EQ5D-5L) (pConclusions: The illness trajectory of COVID-19 includes persisting cardio-renal inflammation, lung damage and hemostasis activation. Adjudicated myocarditis occurred in one in eight hospitalized patients and was associated with impairments in health status, physical and psychological wellbeing during community convalescence. Public registration: ClinicalTrials.gov identifier is NCT04403607.

Background: Cut off values for change in left ventricular end-diastolic volume (LVEDV) and LV end-systolic volume (LVESV) by cardiovascular magnetic resonance following ST-segment–elevation myocardial infarction have recently been proposed and 4 patterns of LV remodeling were described. We aimed to assess their long-term prognostic significance. Methods: A prospective cohort of unselected patients with ST-segment–elevation myocardial infarction with paired acute and 6-month cardiovascular magnetic resonance, with the 5-year composite end point of all-cause death and hospitalization for heart failure was included. The prognosis of the following groups (group 1: reverse LV remodeling [≥12% decrease in LVESV]; group 2: no LV remodeling [changes in LVEDV and LVESV Results: Two hundred eighty-five patients were included with a median follow-up was 5.8 years. The composite end point occurred in 9.5% in group 1, 12.3% in group 2, 7.1% in group 3, and 24.2% in group 4. Group 4 had significantly higher cumulative event rates of the composite end point (log-rank test, P =0.03) with the other 3 groups showing similar cumulative event rates (log-rank test, P =0.51). Cox proportional hazard for group 2 (hazard ratio, 1.3 [95% CI, 0.6–3.1], P =0.53) and group 3 (hazard ratio, 0.6 [95% CI, 0.2–2.3], P =0.49) were not significantly different but was significantly higher in group 4 (hazard ratio, 3.0 [95% CI, 1.2–7.1], P =0.015) when compared with group 1. Conclusions: Patients with ST-segment–elevation myocardial infarction developing adverse LV remodeling at 6 months, defined as ≥12% increase in both LVESV and LVEDV by cardiovascular magnetic resonance, was associated with worse long-term clinical outcomes than those with adverse LV remodeling with compensation, reverse LV remodeling, and no LV remodeling, with the latter 3 groups having similar outcomes in a cohort of stable reperfused patients with ST-segment–elevation myocardial infarction. Registration URL: http://www.clinicaltrials.gov . Unique identifier: NCT02072850.

Background: Stents immediately implanted in thrombus-laden arteries cause embolization, which paradoxically impairs myocardial reperfusion and function. Methods: We conducted a Bayesian open-label randomized trial across 15 centres in France and Canada. Patients with acute ST-elevation myocardial infarction (STEMI) and reperfused by thrombectomy or small-size balloon angioplasty were randomly assigned to immediate stenting or to a bridging anti-thrombin therapy and delayed stenting between 18h to 48h after reperfusion. Using a hierarchical Bayesian analysis, we borrowed data from exchangeable twin trials to form a posterior probability of the risk ratio (RR) for the combined occurrence of cardiovascular death, heart failure, non-fatal myocardial infarction (MI), or target-vessel revascularisation (TVR) over 9 months in the intent-to-treat populations. Findings: Between April 2014 and September 2017, 305 participants were randomly assigned to delayed (n = 152) or immediate stenting (n = 153). In parallel, four similar RCTs were reported that satisfied exchangeability requirements, leading to 1,873 participants, including 930 assigned to delayed and 943 assigned to immediate stenting. The primary endpoint occurred in 167 participants (18.1%) assigned to delayed stenting compared to 194 participants (20.6%) assigned to immediate stenting (RR, 0.91; 95% credible interval [95%CrI], 0.76 to 1.09; probability of superiority, 89%). Delayed stenting led to a meaningful increase in unplanned target revascularization acutely (RR, 1.54; 95% CrI, 0.98 to 2.41, probability of inferiority, 99%). At long term, delayed stenting reduced the combined occurrence of CV death or heart failure (RR, 0.83; 95% CrI, 0.67 to 1.02, probability of superiority, 99%). Interpretation: In patients with STEMI, delayed stenting did not reduce the occurrence of cardiovascular death, non-fatal MI, heart failure and unplanned TVR compared to the immediate stenting. There is a high probability that delayed stenting substantially reduces cardiovascular death and heart failure in the longer-term. Trial Registration: ClinicalTrials.gov identifier: NCT01542385. Funding Statement: The trial was supported by an operating grant from the peer-reviewed, publically funded Canadian Institute of Health Research (CIHR), through the Industry-Partnered Collaborative Research program (grant #298937), in collaboration with Boston Scientific and AstraZeneca (unrestricted grants support). The industry partners played no role in the conduct and oversight of the study. Declaration of Interests: The investigators disclose the following relationships: E. Marc Jolicoeur: Advisory Board: Institut National d’Excellence en Sante et Services Sociaux du Quebec, Servier, Imbria Pharmaceutical, Carre technology; Board of Directors, Societe de Sciences Vasculaires du Quebec; Data Safety Monitoring Board: XyloCor; Research grants; Boston Scientific, AstraZeneca; The University of Glasgow (employer, C Berry) holds research and/or consultancy agreements with AstraZeneca, Abbott Vascular, Boehringer Ingelheim, GSK, HeartFlow, Novartis and Siemens Healthcare; Francois Roubille: Advisory Board: Abbott, Air liquide, Research grants; Boston Scientific, AstraZeneca. Consultancy agreements with AstraZeneca, Abbott Vascular, Air liquide, Amgen, Boehringer Ingelheim, GSK, MSD, Novartis, Sanofi, Novartis, Novonordisk, Vifor; Geraud Souteyrand: Consultancy agreements; Medtronic, Abbott, and Terumo; Guillaume Cayla: Consultancy agreements; Astra Zeneca, Amgen, Abbot Vascular, BMS, Boston, Biotronik, Medtronic, Pfizer, and Sanofi; Nicolas Delarche: Advisory board: Novartis; Samer Mansour: Consultant/Advisory board/Speaker’s Bureau: Abbott vascular, Soundbite, Boehringer Ingelheim, AstraZeneca, Bayer, BMS-Pfizer Alliance, Medtronic, Amgen, Sanofi, Servier, Gilead and Novartis; Erick Schampaert: Consultant/Advisory board/Speaker’s Bureau: Abbott, AstraZeneca, Bayer, BMS-Pfizer Alliance, Medtronic, Philips-Volcano, Servier; Loic Belle: Research Grant: AstraZeneca, Medtronic, Biotronic, Boston Scientific, Abbott Vascular, Terumo Ethics Approval Statement: The protocol complied with the Declaration of Helsinki and was approved by IRB at each participating centers. The trial was coordinated by the Montreal Health Innovation Coordinating Centre under the direction of the executive committee, which was responsible for trial conduct, the integrity of the data analysis, and the reporting of results.

Background Primary percutaneous coronary intervention is used to restore blood flow in the infarct-related coronary artery, followed by immediate stenting to prevent reocclusion. Stents implanted in thrombus-laden arteries cause distal embolization, which paradoxically impairs myocardial reperfusion and ventricular function. Whether a strategy of delayed stenting improves outcomes in patients with acute ST-elevation myocardial infarction (STEMI) is uncertain. Methods The Primary Reperfusion Secondary Stenting (PRIMACY) is a Bayesian prospective, randomized, open-label, blinded end point trial in which delayed vs immediate stenting in patients with STEMI were compared for prevention of cardiovascular death, nonfatal myocardial infarction, heart failure, or unplanned target vessel revascularization at 9 months. All participants were immediately reperfused, but those assigned to the delayed arm underwent stenting after an interval of 24 to 48 hours. This interval was bridged with antithrombin therapy to reduce thrombus burden. In the principal Bayesian hierarchical random effects analysis, data from exchangeable trials will be combined into a study prior and updated with PRIMACY into a posterior probability of efficacy. Results A total of 305 participants were randomized across 15 centres in France and Canada between April 2014 and September 2017. At baseline, the median age of participants was 59 years, 81% were male, and 3% had a history of percutaneous coronary intervention. Results from PRIMACY will be updated from the patient-level data of 1568 participants enrolled in the Deferred Stent Trial in STEMI (DEFER; United Kingdom), Minimalist Immediate Mechanical Intervention (MIMI; France), Danish Trial in Acute Myocardial Infarction-3 (DANAMI-3; Denmark), and Impact of Immediate Stent Implantation Versus Deferred Stent Implantation on Infarct Size and Microvascular Perfusion in Patients With ST Segment–Elevation Myocardial Infarction (INNOVATION, South Korea) trials. Conclusions We expect to clarify whether delayed stenting can safely reduce the occurrence of adverse cardiovascular end points compared with immediate stenting in patients with STEMI.

Supplemental Digital Content is available in the text., The rationale for our study was to investigate the pathophysiology of microvascular injury in patients with acute ST-segment–elevation myocardial infarction in relation to a history of hypertension. We undertook a cohort study using invasive and noninvasive measures of microvascular injury, cardiac magnetic resonance imaging at 2 days and 6 months, and assessed health outcomes in the longer term. Three hundred twenty-four patients with acute myocardial infarction (mean age, 59 [12] years; blood pressure, 135 [25] / 79 [14] mm Hg; 237 [73%] male, 105 [32%] with antecedent hypertension) were prospectively enrolled during emergency percutaneous coronary intervention. Compared with patients without antecedent hypertension, patients with hypertension were older (63 [12] years versus 57 [11] years; P

The index of microcirculatory resistance (IMR), an invasive measure of microvascular function, has been shown to correlate with clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI). The aim of this study is to evaluate the predictive value of IMR on left ventricular recovery in patients undergoing a pharmacoinvasive strategy for STEMI.The index of microcirculatory resistance was assessed following percutaneous coronary intervention (PCI) in 31 patients with STEMI who were initially managed with thrombolysis. Other markers of microvascular function such as coronary flow reserve (CFR), TIMI flow grade, corrected TIMI frame count (cTFC), and ST-segment resolution were also recorded. All indices were evaluated against measures of left ventricular function and recovery 3 months postindex event.The IMR correlated with left ventricular function, as assessed by wall motion score and ejection fraction at 3-month follow-up (rA¢Â€Â‰=A¢Â€Â‰0.652, PA¢Â€Â‰=A¢Â€Â‰0.005; rA¢Â€Â‰=A¢Â€Â‰-0.452, PA¢Â€Â‰=A¢Â€Â‰0.011, respectively). The traditional methods of assessing microvascular function, such as CFR, TIMI flow grade, cTFC, and ST-segment resolution did not correlate with wall motion score and ejection fraction at 3 months. Post-PCI IMR was significantly lower in those patients with left ventricular recovery at 3 months (18A¢Â€Â‰U vs 39A¢Â€Â‰U, PA¢Â€Â‰

Purpose To investigate the prognostic value of circumferential left ventricular (LV) strain measured by using cardiac MRI for prediction of major adverse cardiac events (MACE) following an acute ST-segment-elevation myocardial infarction (STEMI). Materials and Methods Participants with acute STEMI were prospectively enrolled from May 11, 2011, to November 22, 2012. Cardiac MRI was performed at 1.5 T during the index hospitalization. Displacement encoding with stimulated echoes (DENSE) and feature tracking of cine cardiac MRI was used to assess circumferential LV strain. MACE that occurred after discharge were independently assessed by cardiologists blinded to the baseline observations. Results A total of 259 participants (mean age, 58 years ± 11 [standard deviation]; 198 men [mean age, 58 years ± 11] and 61 women [mean age, 58 years ± 12]) underwent cardiac MRI 2.2 days ± 1.9 after STEMI. Average infarct size was 18% ± 13 of LV mass and circumferential strain was -13% ± 3 (DENSE method) and -24% ± 7 (feature- tracking method). Fifty-one percent (131 of 259 participants) had presence of microvascular obstruction. During a median follow-up period of 4 years, 8% (21 of 259) experienced MACE. Area under the curve (AUC) for DENSE was different from that of feature tracking (AUC, 0.76 vs 0.62; P = .03). AUC for DENSE was similar to that of initial infarct size (P = .06) and extent of microvascular obstruction (P = .08). DENSE-derived strain provided incremental prognostic benefit over infarct size for prediction of MACE (hazard ratio, 1.3; P.01). Conclusion Circumferential strain has independent prognostic importance in study participants with acute ST-segment-elevation myocardial infarction. Published under a CC BY 4.0 license. Online supplemental material is available for this article. See also the editorial by Kramer in this issue.

Objective We hypothesized that Displacement Encoding with Stimulated Echoes (DENSE) and feature-tracking derived circumferential strain would provide incremental prognostic value over the extent of infarction for recovery of segmental myocardial function. Methods Two hundred and sixty-one patients (mean age 59 years, 73% male) underwent MRI 2 days post-ST elevation myocardial infarction (STEMI) and 241 (92%) underwent repeat imaging 6 months later. The MRI protocol included cine, 2D-cine DENSE, T2 mapping and late enhancement. Wall motion scoring was assessed by 2-blinded observers and adjudicated by a third. (WMS: 1=normal, 2=hypokinetic, 3=akinetic, 4=dyskinetic). WMS improvement was defined as a decrease in WMS ≥ 1, and normalization where WMS = 1 on follow-up. Segmental circumferential strain was derived utilizing DENSE and feature-tracking. A generalized linear mixed model with random effect of subject was constructed and used to account for repeated sampling when investigating predictors of segmental myocardial improvement or normalization Results At baseline and follow-up, 1416 segments had evaluable data for all parameters. Circumferential strain by DENSE (p

Clinical introductionA 50-year-old woman presented with an inferoposterior ST-elevation myocardial infarction (STEMI) and underwent emergency percutaneous coronary intervention (PCI). Angiography revealed acute occlusion of the circumflex and right coronary (RCA) arteries. PCI was uncomplicated. Her medical history included asthma, hypertension and chronic sinusitis.Three months later, she presented with a non-STEMI (NSTEMI), and angiogram showed a new focal stenosis in the left anterior descending artery. Pressure wire assessment induced severe coronary spasm. After liberal intracoronary nitrate, fractional flow reserve measured 0.71, so a further stent was implanted. Six days later, she was readmitted with another NSTEMI. Repeat angiogram revealed patent stents, with severe spasm of the distal RCA which improved following nitrate (figure 1A,B). Four days later, she was readmitted with further NSTEMI. Coronary angiography was not felt to be appropriate, and she was discharged with vasodilator therapy.Figure 1(A) Angiogram of RCA pre nitrates; (B) Angiogram of RCA post nitrates; (C) CT brain post cardiac arrest; (D) CMR post cardiac arrest.The following day, she had an out-of-hospital ventricular fibrillation (VF) arrest and was successfully resuscitated. CT brain showed no evidence of neurological injury (figure 1C). Cardiac magnetic resonance imaging (CMR) was performed prior to implantable cardioverter defibrillator (ICD) implantation (figure 1D). Eosinophils had been persistently elevated with a peak of 1.78×109 (normal: 0.02–0.5×109). Antinuclear antibodies and antineutrophil cytoplasmic antibodies (ANCA) were negative.Question?What is the diagnosis for her recurrent acute coronary syndrome and VF arrest?Aggressive atherosclerotic coronary artery disease.Prinzmetal’s variant angina.Loeffler endocarditis.Coronary vasculitis.

Background Invasive measures of microvascular resistance in the culprit coronary artery have potential for risk stratification in acute ST‐segment–elevation myocardial infarction. We aimed to investigate the pathological and prognostic significance of coronary thermodilution waveforms using a diagnostic guidewire. Methods and Results Coronary thermodilution was measured at the end of percutaneous coronary intervention, (PCI) and contrast‐enhanced cardiac magnetic resonance imaging (MRI) was intended on day 2 and 6 months later to assess left ventricular (LV) function and pathology. All‐cause death or first heart failure hospitalization was a pre‐specified outcome (median follow‐up duration 1469 days). Thermodilution recordings underwent core laboratory assessment. A total of 278 patients with acute ST‐segment elevation myocardial infarction EMI (72% male, 59±11 years) had coronary thermodilution measurements classified as narrow unimodal (n=143 [51%]), wide unimodal (n=100 [36%]), or bimodal (n=35 [13%]). Microvascular obstruction and myocardial hemorrhage were associated with the thermodilution waveform pattern ( P =0.007 and 0.011, respectively), and both pathologies were more prevalent in patients with a bimodal morphology. On multivariate analysis with baseline characteristics, thermodilution waveform status was a multivariable associate of microvascular obstruction (odds ratio [95% confidence interval]=5.29 [1.73, 16.22];, P =0.004) and myocardial hemorrhage (3.45 [1.16, 10.26]; P =0.026), but the relationship was not significant when index of microvascular resistance (IMR) >40 or change in index of microvascular resistance (5 per unit) was included. However, a bimodal thermodilution waveform was independently associated with all‐cause death and hospitalization for heart failure (odds ratio [95% confidence interval]=2.70 [1.10, 6.63]; P =0.031), independent of index of microvascular resistance>40, ST‐segment resolution, and TIMI (Thrombolysis in Myocardial Infarction) Myocardial Perfusion Grade. Conclusions The thermodilution waveform in the culprit coronary artery is a biomarker of prognosis and may be useful for risk stratification immediately after reperfusion therapy.

The aim of this study was to mechanistically investigate associations among cigarette smoking, microvascular pathology, and longer term health outcomes in patients with acute ST-segment elevation myocardial infarction (MI).The pathophysiology of myocardial reperfusion injury and prognosis in smokers with acute ST-segment elevation MI is incompletely understood.Patients were prospectively enrolled during emergency percutaneous coronary intervention. Microvascular function in the culprit artery was measured invasively. Contrast-enhanced magnetic resonance imaging (1.5-T) was performed 2 days and 6 months post-MI. Infarct size and microvascular obstruction were assessed using late gadolinium enhancement imaging. Myocardial hemorrhage was assessed with T2* mapping. Pre-specified endpoints included: 1) all-cause death or first heart failure hospitalization; and 2) cardiac death, nonfatal MI, or urgent coronary revascularization (major adverse cardiovascular events). Binary logistic regression (odds ratio [OR] with 95% confidence interval [CI]) with smoking status was used.In total, 324 patients with ST-segment elevation MI were enrolled (mean age 59 years, 73% men, 60% current smokers). Current smokers were younger (age 55 ± 11 years vs. 65 ± 10 years, p 0.001), with fewer patients with hypertension (52 ± 27% vs. 53 ± 41%, p = 0.007). Smokers had better TIMI (Thrombolysis In Myocardial Infarction) flow grade (≥2 vs. ≤1, p = 0.024) and ST-segment resolution (none vs. partial vs. complete, p = 0.010) post-percutaneous coronary intervention. On day 1, smokers had higher circulating C-reactive protein, neutrophil, and monocyte levels. Two days post-MI, smoking independently predicted infarct zone hemorrhage (OR: 2.76; 95% CI: 1.42 to 5.37; p = 0.003). After a median follow-up period of 4 years, smoking independently predicted all-cause death or heart failure events (OR: 2.20; 95% CI: 1.07 to 4.54) and major adverse cardiovascular events (OR: 2.79; 95% CI: 2.30 to 5.99).Smoking is associated with enhanced inflammation acutely, infarct-zone hemorrhage subsequently, and longer term adverse cardiac outcomes. Inflammation and irreversible myocardial hemorrhage post-MI represent mechanistic drivers for adverse long-term prognosis in smokers. (Detection and Significance of Heart Injury in ST Elevation Myocardial Infarction. [BHF MR-MI]; NCT02072850).

Background Remote ischaemic preconditioning (RIPC) is a cardioprotective intervention invoking intermittent ischaemia in a tissue remote from the heart. Its mechanisms are incompletely understood. We hypothesised that RIPC might enhance coronary vasodilatation by an endothelium-dependent mechanism. Methods We performed a prospective, randomised, sham-controlled, blinded clinical trial. Patients with stable coronary artery disease undergoing elective angiography were randomised 1:1 to RIPC or sham. Endothelial-dependent and –independent function was assessed with intracoronary (ic) acetylcholine (ACh) and ic nitrate, respectively. Coronary luminal diameter was assessed by QCA. Primary outcome: between-group difference in mean% change in coronary luminal diameter following ACh. Results Following angiography, 60/75 patients (mean ±SD age 57.5±8.5 years; 80% male) were eligible and completed the protocol (n=30 RIPC, n=30 sham). The mean% change in coronary luminal diameter was −13.3±22.3% and −2.0±17.2% in the sham and RIPC groups respectively (difference 11.32%, 95% CI: 1.2 to 21.4, p=0.032) (figure 1). This remained significant with age and sex as covariates (difference 11.01%, 1.01–21.0, p=0.035). Conclusions RIPC attenuates the extent of vasoconstriction induced by intracoronary acetylcholine infusion, and this endothelium-dependent mechanism may contribute to its cardioprotective effects.

Aims The differential diagnosis of patients with early non-ischaemic dilated cardiomyopathy (DCM) and those with physiological adaptation to exercise (‘athlete's heart’) may be difficult as many of the morphological adaptations are shared in the two conditions. Increased physical fitness is becoming more common in later adulthood, a group in whom there may be even more diagnostic difficulty. We hypothesized that tissue characterization using cardiovascular magnetic resonance (CMR) T 1 and T 2 mapping would be able to differentiate between patients with left ventricular (LV) dilatation due to early DCM and exercisers. Methods and results Fifty-eight middle-aged males [21 healthy controls, 21 males with a history of aerobic exercise and LV ejection fraction (LVEF) 45–55%, and 16 patients with DCM and LVEF 45–55%] underwent a CMR protocol including T 1 and T 2 mapping and calculation of extracellular volume (ECV) using a 1.5 T MRI scanner. Native T 1, ECV, and T 2 relaxation times were significantly increased in DCM patients compared with controls (native T 1 1017 ± 42 vs. 952 ± 31 ms, P < 0.001; ECV 31.2 ± 4.1 vs. 26.2 ± 2.9%, P = 0.003; T 2 55.9 ± 4.4 vs. 52.9 ± 3.3 ms, P = 0.05) and exercisers (native T 1 957 ± 32 ms, P < 0.001; ECV 26.3 ± 3.6%, P = 0.004; T 2 52.8 ± 3.2 ms, P = 0.042). Using multivariable logistic regression, native T 1 gave the best differentiation between exercisers and sedentary patients with early DCM (area under the curve 0.91). Conclusion T 1 and T 2 mapping are potentially useful tools for differentiating between athlete's heart and patients with early DCM, and could be used whenever differentiation between these two phenotypes is inconclusive using standard imaging techniques.

Objectives This study aimed to assess the incremental prognostic value of global circumferential strain (GCS), as measured using cardiac magnetic resonance (CMR) tagging, in addition to baseline clinical characteristics, left ventricular ejection fraction (LVEF), and late gadolinium enhancement (LGE), in the prediction of major adverse cardiovascular events (MACE) in an unselected cohort of patients. Background LVEF is a powerful predictor of mortality and is used for guiding treatment decisions. It is, however, subject to limitations. The value of GCS measured by CMR tagging in patients with suspected cardiac disease has not been fully explored despite its being considered as the gold standard noninvasive method of assessment of LV deformation. Methods We prospectively evaluated data from 539 consecutive patients referred for CMR who underwent a CMR protocol that included cine imaging, tagging, and LGE. The primary endpoint was the prevalence of MACE, defined as a composite of all-cause mortality, heart failure–related hospitalization, and aborted sudden cardiac death. Results MACE occurred in 62 of 539 patients (11.5%) over a mean follow-up period of 2.2 years. History of ischemic heart disease (IHD) and beta-blocker use were both significant clinical predictors of adverse outcomes. All 3 CMR parameters were significant multivariate predictors of the primary outcome when added to significant clinical predictors (LVEF, hazard ratio [HR]: 0.96 [95% confidence interval [CI]: 0.94 to 0.99; p = 0.005]; presence of LGE, HR: 2.07 [95% CI: 1.03 to 4.14; p = 0.04]; GCS, HR: 1.11 [95% CI: 1.02 to 1.21; p = 0.041]). Global chi-square increased significantly with the addition of both LGE and GCS. Both the presence of LGE and reduced GCS had independent prognostic value in the overall cohort. Patients with LVEF ≥35% but LGE present and reduced GCS had a poor outcome similar to that in those with LVEF Conclusions We found, in a large-scale cohort of patients, that GCS, in addition to clinical variables, LVEF, and LGE, had incremental independent prognostic value. This measure could provide further risk stratification, especially in patients with mild LV impairment.

Adenosine is a ubiquitous extracellular signaling molecule with essential functions in human physiology. Due to the widespread expression of adenosine receptors, it has far-reaching effects across many different organ systems. With a prominent role in the cardiovascular system, it has been extensively studied for both its therapeutic and diagnostic abilities. One of the key areas of use is in the coronary circulation whereby adenosine produces a hyperemic response. An important target of adenosine is the coronary microcirculation whereby adenosine acts as a prominent vasodilator with many of the beneficial effects of adenosine reflected in its capacity to affect the microvessels. Adenosine also has an important role in the pre-conditioned state and also in the attenuation of ischemia-reperfusion injury. This review examines the physiology, pharmacology, and therapeutic applications of adenosine in the human cardiovascular system and provides a brief overview of important aspects of the adenosine-cardiac interaction. It also examines the role of adenosine in the coronary hyperemic response and discusses the use of adenosine for this purpose. After recent concerns about the use of adenosine, a discussion regarding safety of this drug is provided. A brief review of novel agents used to initiate coronary hyperemia is also provided.

The index of microvascular resistance (IMR) predicts presence of microvascular obstruction (MVO) on cardiovascular magnetic resonance (CMR) imaging & prognosis in acute STEMI, but discordance between IMR & MVO occurs in about one third of cases. We studied the predictive value of a new parameter

Acute myocardial infarction (AMI) is a leading cause of mortality and morbidity in the world, despite the rate having significantly declined over the past decade. The aim of this review is to consider the emerging diagnostic and clinical utility of cardiac MRI in patients with recent AMI. Cardiac MRI has high reproducibility and accuracy, allowing detailed functional assessment and characterisation of myocardial tissue. In addition to traditional measures including infarct size (IS), transmural extent of necrosis and microvascular obstruction (MVO), other infarct characteristics can now be identified using innovative MRI techniques. These novel pathologies include myocardial oedema and myocardial haemorrhage which also have functional and prognostic implications for patients. In addition to its diagnostic utility in ordinary clinical practice, cardiac MRI has been increasingly used to provide information on surrogate outcome measures, such as left ventricular ejection fraction (LVEF) and volumes, in clinical trials. MRI is becoming more available in secondary care, however, the potential clinical utility and cost effectiveness of MRI in post-MI patients remains uncertain. Cardiac MRI is most likely to be useful in high risk patients with risk factors for heart failure (HF). This includes individuals with early signs of pump failure and risk factors for adverse remodelling, such as MVO. This review focuses on the role of cardiac MRI in the assessment of patients with AMI.

Cardiac magnetic resonance (CMR) imaging enables the assessment of left ventricular function and pathology. In addition to established contrast-enhanced methods for the assessment of infarct size and microvascular obstruction, other infarct pathologies, such as myocardial edema and myocardial hemorrhage, can be identified using innovative CMR techniques. The initial extent of myocardial edema revealed by T2-weighted CMR has to be stable for edema to be taken as a retrospective marker of the area-at-risk, which is used to calculate myocardial salvage. The timing of edema assessment is important and should be focused within 2 - 7 days post-reperfusion. Some recent investigations have called into question the diagnostic validity of edema imaging after acute STEMI. Considering the results of these studies, as well as results from our own laboratory, we conclude that the time-course of edema post-STEMI is unimodal, not bimodal. Myocardial hemorrhage is the final consequence of severe vascular injury and a progressive and prognostically important complication early post-MI. Myocardial hemorrhage is a therapeutic target to limit reperfusion injury and infarct size post-STEMI.

The index of microcirculatory resistance (IMR), an invasive measure of microvascular function, has been shown to correlate with clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI). The aim of this study is to evaluate the predictive value of IMR on left ventricular recovery in patients undergoing a pharmacoinvasive strategy for STEMI.The index of microcirculatory resistance was assessed following percutaneous coronary intervention (PCI) in 31 patients with STEMI who were initially managed with thrombolysis. Other markers of microvascular function such as coronary flow reserve (CFR), TIMI flow grade, corrected TIMI frame count (cTFC), and ST-segment resolution were also recorded. All indices were evaluated against measures of left ventricular function and recovery 3 months postindex event.The IMR correlated with left ventricular function, as assessed by wall motion score and ejection fraction at 3-month follow-up (r = 0.652, P = 0.005; r = -0.452, P = 0.011, respectively). The traditional methods of assessing microvascular function, such as CFR, TIMI flow grade, cTFC, and ST-segment resolution did not correlate with wall motion score and ejection fraction at 3 months. Post-PCI IMR was significantly lower in those patients with left ventricular recovery at 3 months (18 U vs 39 U, P 0.001). The optimal cut-off value for post-PCI IMR and left ventricular recovery was 32 U. In patients in whom the IMR was greater than 32 U, the percent change in ejection fraction was significantly lower than in those patients in whom the IMR was less than 32 U (2 ± 11 vs 12 ± 8, P = 0.012).In patients presenting with STEMI initially managed with thrombolysis and subsequently undergoing PCI, IMR correlates with measures of left ventricular function and has the potential to predict left ventricular recovery at 3 months.

Supplemental Digital Content is available in the text., The natural history and pathophysiological significance of tissue remodeling in the myocardial remote zone after acute ST-elevation myocardial infarction (STEMI) is incompletely understood. Extracellular volume (ECV) in myocardial regions of interest can now be measured with cardiac magnetic resonance imaging. Patients who sustained an acute STEMI were enrolled in a cohort study (BHF MR-MI [British Heart Foundation Magnetic Resonance Imaging in Acute ST-Segment Elevation Myocardial Infarction study]). Cardiac magnetic resonance was performed at 1.5 Tesla at 2 days and 6 months post STEMI. T1 modified Look-Locker inversion recovery mapping was performed before and 15 minutes after contrast (0.15 mmol/kg gadoterate meglumine) in 140 patients at 2 days post STEMI (mean age: 59 years, 76% male) and in 131 patients at 6 months post STEMI. Remote zone ECV was lower than infarct zone ECV (25.6±2.8% versus 51.4±8.9%; P

Purpose To assess myocardial strain using cine displacement encoding with stimulated echoes (DENSE) using 1.5T and 3.0T MRI in healthy adults. Materials and Methods Healthy adults without any history of cardiovascular disease underwent magnetic resonance imaging (MRI) at 1.5T and 3.0T within 2 days. The MRI protocol included balanced steady‐state free‐precession (b‐SSFP), 2D cine‐echo planar imaging (EPI)‐DENSE, and late gadolinium enhancement in subjects >45 years. Acquisitions were divided into six segments; global and segmental peak longitudinal and circumferential strain were derived and analyzed by field strength, age, and gender. Results In all, 89 volunteers (mean age 44.8 ± 18.0 years, range: 18–87 years) underwent MRI at 1.5T, and 88 of these subjects underwent MRI at 3.0T (1.4 ± 1.4 days between the scans). Compared with 3.0T, the magnitudes of global circumferential (–19.5 ± 2.6% vs. –18.47 ± 2.6%; P = 0.001) and longitudinal (–12.47 ± 3.2% vs. –10.53 ± 3.1%; P = 0.004) strain were greater at 1.5T. At 1.5T, longitudinal strain was greater in females than in males: –10.17 ± 3.4% vs. –13.67 ± 2.4%; P = 0.001. Similar observations occurred for circumferential strain at 1.5T (–18.72 ± 2.2% vs. –20.10 ± 2.7%; P = 0.014) and at 3.0T (–17.92 ± 1.8% vs. –19.1 ± 3.1%; P = 0.047). At 1.5T, longitudinal and circumferential strain were not associated with age after accounting for sex (longitudinal strain P = 0.178, circumferential strain P = 0.733). At 3.0T, longitudinal and circumferential strain were associated with age (P < 0.05). Longitudinal strain values were greater in the apico‐septal, basal‐lateral, and mid‐lateral segments and circumferential strain in the inferior, infero‐lateral, and antero‐lateral LV segments. Conclusion Myocardial strain parameters as revealed by cine‐DENSE at different MRI field strengths were associated with myocardial region, age, and sex. J. Magn. Reson. Imaging 2016;44:1197–1205.

Supplemental Digital Content is available in the text., Background— The success of coronary reperfusion therapy in ST-segment–elevation myocardial infarction (MI) is commonly limited by failure to restore microvascular perfusion. Methods and Results— We performed a prospective cohort study in patients with reperfused ST-segment–elevation MI who underwent cardiac magnetic resonance 2 days (n=286) and 6 months (n=228) post MI. A serial imaging time-course study was also performed (n=30 participants; 4 cardiac magnetic resonance scans): 4 to 12 hours, 2 days, 10 days, and 7 months post reperfusion. Myocardial hemorrhage was taken to represent a hypointense infarct core with a T2* value of

The index of microvascular resistance (IMR) is a direct, invasive test of coronary microvascular resistance [(1)][1]. When measured in the culprit coronary artery after emergency percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI), IMR is well established

Background— The use of fractional flow reserve (FFR) in acute coronary syndromes is controversial. The British Heart Foundation Fractional Flow Reserve Versus Angiography in Guiding Management to Optimize Outcomes in Non-ST-Elevation Myocardial Infarction (FAMOUS-NSTEMI) study (NCT01764334) has recently demonstrated the safety and feasibility of FFR measurement in patients with non–ST-segment–elevation myocardial infarction. We report the findings of the cardiac magnetic resonance (CMR) substudy to assess the diagnostic accuracy of FFR compared with 3.0-T stress CMR perfusion. Methods and Results— One hundred six patients with non–ST-segment–elevation myocardial infarction who had been referred for early invasive management were included from 2 centers. FFR was measured in all major patent epicardial coronary arteries with a visual stenosis estimated at ≥30%, and if percutaneous coronary intervention was performed, an FFR assessment was repeated. Myocardial perfusion was assessed with stress perfusion CMR at 3 T. The mean age was 56.7±9.8 years; 82.6% were men. Mean time from FFR evaluation to CMR was 6.1±3.1 days. The mean±SD left ventricular ejection fraction was 58.2±9.1%. Mean infarct size was 5.4±7.1%, and mean troponin concentration was 5.2±9.2 μg/L. There were 34 fixed and 160 inducible perfusion defects. There was a negative correlation between the number of segments with a perfusion abnormality and FFR ( r =−0.77; P P Conclusions— FFR in patients with recent non–ST-segment–elevation myocardial infarction showed high concordance with myocardial perfusion in matched territories as revealed by 3.0-T stress perfusion CMR. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT02073422.

Aims Coronary guidewire-based diagnostic assessments with hyperemia may cause iatrogenic complications. We assessed the safety of guidewire-based measurement of coronary physiology, using intravenous adenosine, in patients with an acute coronary syndrome. Methods We prospectively enrolled invasively managed STEMI and NSTEMI patients in two simultaneously conducted studies in 6 centers (NCT01764334; NCT02072850). All of the participants underwent a diagnostic coronary guidewire study using intravenous adenosine (140 μg/kg/min) infusion for 1–2 min. The patients were prospectively assessed for the occurrence of serious adverse events (SAEs) and symptoms and invasively measured hemodynamics were also recorded. Results 648 patients (n = 298 STEMI patients in 1 hospital; mean time to reperfusion 253 min; n = 350 NSTEMI in 6 hospitals; median time to angiography from index chest pain episode 3 (2, 5) days) were included between March 2011 and May 2013. Two NSTEMI patients (0.3% overall) experienced a coronary dissection related to the guidewire. No guidewire dissections occurred in the STEMI patients. Chest symptoms were reported in the majority (86%) of patient's symptoms during the adenosine infusion. No serious adverse events occurred during infusion of adenosine and all of the symptoms resolved after the infusion ceased. Conclusions In this multicenter analysis, guidewire-based measurement of FFR and IMR using intravenous adenosine was safe in patients following STEMI or NSTEMI. Self-limiting symptoms were common but not associated with serious adverse events. Finally, coronary dissection in STEMI and NSTEMI patients was noted to be a rare phenomenon.

The significance of remote myocardium in the natural history of STEMI is uncertain. Cardiac magnetic resonance (CMR) depicts left ventricular (LV) dimension and pathology. Native T1 quantified by CMR (T1 proton relaxation time, milliseconds) is a fundamental tissue property determined by water

Background CMR has become an increasingly valuable tool in the diagnosis and risk stratification of patients with nonischaemic dilated cardiomyopathy (DCM) due to its assessment of left ventricular systolic function and tissue characterization ability and may have a role in early identification of cardiomyopathy. Some of the changes associated with early DCM (left ventricular dilatation and mild reduction in LV ejection fraction) can also occur in patients with a history of significant aerobic exercise, known as “athlete’s heart”. Using standard echocardiographic and CMR parameters it may be difficult to differentiate between DCM and normal physiological athletic adaptation, which may have significant implications for the patient. We hypothesized that use of CMR tagging and T1 and T2 mapping might be useful to differentiate between patients with left ventricular dilatation due to DCM and athlete’s heart.

Background Left ventricular ejection fraction (LVEF) is powerful predictor of mortality and is used to guide treatment decisions. It is however subject to limitations, particularly when measured using echocardiography, as is most commonly done. Additionally, many major cardiovascular events occur in patients typically adjudged to be at lower risk using echocardiography (LVEF >35%). Assessment of myocardial deformation (strain) using tagging has the potential to overcome some of the limitations of LVEF. The value of global circumferential strain (GCS) measured by CMR tagging in patients with suspected cardiac disease has not been fully explored despite it being considered as the non-invasive gold standard method of assessment of LV deformation. We aimed to assess the incremental prognostic value of GCS measured using tagging for the prediction of major adverse cardiovascular events in addition to baseline clinical characteristics, LVEF and late gadolinium enhancement (LGE) in an unselected cohort of patients.

To assess the prognostic significance of infarct core tissue characteristics using cardiac magnetic resonance (CMR) imaging in survivors of acute ST-elevation myocardial infarction (STEMI).We performed an observational prospective single centre cohort study in 300 reperfused STEMI patients (mean ± SD age 59 ± 12 years, 74% male) who underwent CMR 2 days and 6 months post-myocardial infarction (n = 267). Native T1 was measured in myocardial regions of interest (n = 288). Adverse remodelling was defined as an increase in left ventricular (LV) end-diastolic volume ≥20% at 6 months. All-cause death or first heart failure hospitalization was a pre-specified outcome that was assessed during follow-up (median duration 845 days). One hundred and sixty (56%) patients had a hypo-intense infarct core disclosed by native T1. In multivariable regression, infarct core native T1 was inversely associated with adverse remodelling [odds ratio (95% confidence interval (CI)] per 10 ms reduction in native T1: 0.91 (0.82, 0.00); P = 0.061). Thirty (10.4%) of 288 patients died or experienced a heart failure event and 13 of these events occurred post-discharge. Native T1 values (ms) within the hypo-intense infarct core (n = 160 STEMI patients) were inversely associated with the risk of all-cause death or first hospitalization for heart failure post-discharge (for a 10 ms increase in native T1: hazard ratio 0.730, 95% CI 0.617, 0.863; P0.001) including after adjustment for left ventricular ejection fraction, infarct core T2 and myocardial haemorrhage. The prognostic results for microvascular obstruction were similar.Infarct core native T1 represents a novel non-contrast CMR biomarker with potential for infarct characterization and prognostication in STEMI survivors. Confirmatory studies are warranted. CLINICALTRIALS.NCT02072850.

Background: Myocardial longitudinal relaxation time (T1, ms) is a fundamental magnetic property of tissue that is related to water content and mobility. The pathophysiological and prognostic importance of native myocardial T1 values in acute STEMI patients is unknown. We aimed to assess the clinical significance of infarct tissue characteristics using native T1 cardiac magnetic resonance (CMR).\ud \ud Methods: We performed a prospective single center cohort study in reperfused STEMI patients who underwent CMR 2 days and 6 months post-MI. Native T1 CMR (MOLLI investigational prototype sequence: 3 (3) 3 (3) 5) was measured in myocardial regions-of-interest. The area-at-risk and infarct territory were depicted with T1 mapping and late gadolinium contrast enhancement imaging, respectively. All-cause death or heart failure hospitalization was a pre-specified outcome that was assessed during follow-up.\ud \ud Results: 300 STEMI patients (mean±SD age 59±12 years, 74% male, 114 with anterior STEMI) gave informed consent and had CMR (14 July 2011 - 22 November 2012). Of these, 288 STEMI patients had evaluable T1 maps and follow-up assessments (median duration 845 days). Infarct size was 18 ±14% of left ventricular mass. Microvascular obstruction occurred in 160 (55.6%) patients. Native T1 within the area-at-risk (1097 ±52 ms) was higher than in the remote zone (961 ±25 ms; p