Cardiovascular magnetic resonance of scar and ischemia burden early after acute ST elevation and non-ST elevation myocardial infarction

Temporal Trends in Race and Sex Differences in Cardiac Arrest Mortality in the USA, 1999-2020

BACKGROUND

Cardiac arrest (CA) affects over 600,000 patients in the USA annually. Despite large-scale public health and educational initiatives, survival rates are lower in certain racial and socioeconomic groups.

METHODS

A county-level cross-sectional longitudinal study using death data of patients aged 15 years or more from the US Centers for Disease Control and Prevention's Wide-Ranging Online Data for Epidemiologic Research (WONDER) database from 1999 to 2020. CAs were identified using the International Classification of Diseases, tenth revision, clinical modification codes.

RESULTS

The CA-related deaths between 1999 and 2020 were 7,710,211 in the entire USA. The annual CA related age-adjusted mortality rates (CA-MR) declined through 2019 (132.9 to 89.7 per 100,000 residents), followed by an increase in 2020 (104.5 per 100,000). White patients constituted 82 % of all deaths and 51 % were female. The overall CA-MR during the study period was 104.48 per 100,000 persons. The CA-MR was higher for men as compared with women (123.5 vs. 89.7 per 100,000) and higher for Black as compared with White adults (154.4 vs. 99.1 per 100,000).

CONCLUSIONS

CA-MR in the overall population has declined, followed by an increase in 2020, which is likely the impact of the COVID-19 pandemic. There were also significant racial and sex differences in mortality rates.

In Vivo Fluorine Imaging Using 1.5 Tesla MRI for Depiction of Experimental Myocarditis in a Rodent Animal Model

The usefulness of perfluorocarbon nanoemulsions for the imaging of experimental myocarditis has been demonstrated in a high-field 9.4 Tesla MRI scanner. Our proof-of-concept study investigated the imaging capacity of PFC-based ¹⁹F/¹H MRI in an animal myocarditis model using a clinical field strength of 1.5 Tesla. To induce experimental myocarditis, five male rats (weight ~300 g, age ~50 days) were treated with one application per week of doxorubicin (2 mg/kg BW) over a period of six weeks. Three control animals received the identical volume of sodium chloride 0.9% instead. Following week six, all animals received a single 4 ml injection of an 20% oil-in-water perfluorooctylbromide nanoemulsion 24 hours prior to in vivo¹H/¹⁹F imaging on a 1.5 Tesla MRI. After euthanasia, cardiac histology and immunohistochemistry using CD68/ED1 macrophage antibodies were performed, measuring the inflamed myocardium in μm² for further statistical analysis to compare the extent of the inflammation with the ¹⁹F-MRI signal intensity. All animals treated with doxorubicin showed a specific signal in the myocardium, while no myocardial signal could be detected in the control group. Additionally, the doxorubicin group showed a significantly higher SNR for ¹⁹F and a stronger CD68/ED1 immunhistoreactivity compared to the control group. This proof-of-concept study demonstrates that perfluorocarbon nanoemulsions could be detected in an in vivo experimental myocarditis model at a currently clinically relevant field strength.

Understanding and Improving Risk Assessment After Myocardial Infarction Using Automated Left Ventricular Shape Analysis

BACKGROUND

Left ventricular ejection fraction (LVEF) and end-systolic volume (ESV) remain the main imaging biomarkers for post-acute myocardial infarction (AMI) risk stratification. However, they are limited to global systolic function and fail to capture functional and anatomical regional abnormalities, hindering their performance in risk stratification.

OBJECTIVES

This study aimed to identify novel 3-dimensional (3D) imaging end-systolic (ES) shape and contraction descriptors toward risk-related features and superior prognosis in AMI.

METHODS

A multicenter cohort of AMI survivors (n = 1,021; median age 63 years; 74.5% male) who underwent cardiac magnetic resonance (CMR) at a median of 3 days after infarction were considered for this study. The clinical endpoint was the 12-month rate of major adverse cardiac events (MACE; n = 73), consisting of all-cause death, reinfarction, and new congestive heart failure. A fully automated pipeline was developed to segment CMR images, build 3D statistical models of shape and contraction in AMI, and find the 3D patterns related to MACE occurrence.

RESULTS

The novel ES shape markers proved to be superior to ESV (median cross-validated area under the receiver-operating characteristic curve 0.681 [IQR: 0.679-0.684] vs 0.600 [IQR: 0.598-0.602]; P < 0.001); and 3D contraction to LVEF (0.716 [IQR: 0.714-0.718] vs 0.681 [IQR: 0.679-0.684]; P < 0.001) in MACE occurrence prediction. They also contributed to a significant improvement in a multivariable setting including CMR markers, cardiovascular risk factors, and basic patient characteristics (0.747 [IQR: 0.745-0.749]; P < 0.001). Based on these novel 3D descriptors, 3 impairments caused by AMI were identified: global, anterior, and basal, the latter being the most complementary signature to already known predictors.

CONCLUSIONS

The quantification of 3D differences in ES shape and contraction, enabled by a fully automated pipeline, improves post-AMI risk prediction and identifies shape and contraction patterns related to MACE occurrence.

Very early invasive angiography versus standard of care in higher-risk non-ST elevation myocardial infarction: study protocol for the prospective multicentre randomised controlled RAPID N-STEMI trial

BACKGROUND

There are a paucity of randomised data on the optimal timing of invasive coronary angiography (ICA) in higher-risk patients with non-ST elevation myocardial infarction (N-STEMI). International guideline recommendations for early ICA are primarily based on retrospective subgroup analyses of neutral trials.

AIMS

The RAPID N-STEMI trial aims to determine whether very early percutaneous revascularisation improves clinical outcomes as compared with a standard of care strategy in higher-risk N-STEMI patients.

METHODS AND ANALYSIS

RAPID N-STEMI is a prospective, multicentre, open-label, randomised-controlled, pragmatic strategy trial. Higher-risk N-STEMI patients, as defined by Global Registry of Acute Coronary Events 2.0 score ≥118, or >90 with at least one additional high-risk feature, were randomised to either: very early ICA±revascularisation or standard of care timing of ICA±revascularisation. The primary outcome is the proportion of participants with at least one of the following events (all-cause mortality, non-fatal myocardial infarction and hospital admission for heart failure) at 12 months. Key secondary outcomes include major bleeding and stroke. A hypothesis generating cardiac magnetic resonance (CMR) substudy will provide mechanistic data on infarct size, myocardial salvage and residual ischaemia post percutaneous coronary intervention. On 7 April 2021, the sponsor discontinued enrolment due to the impact of the COVID-19 pandemic and lower than expected event rates. 425 patients were enrolled, and 61 patients underwent CMR.

ETHICS AND DISSEMINATION

The trial has been reviewed and approved by the East of England Cambridge East Research Ethics Committee (18/EE/0222). The study results will be submitted for publication within 6 months of completion.

TRIAL REGISTRATION NUMBER

NCT03707314; Pre-results.

Predictors of subclinical systemic sclerosis primary heart involvement characterised by microvasculopathy and myocardial fibrosis

OBJECTIVES

SSc primary heart involvement (SSc-pHI) is a significant cause of mortality. We aimed to characterize and identify predictors of subclinical SSc-pHI using cardiovascular MRI.

METHODS

A total of 83 SSc patients with no history of cardiovascular disease or pulmonary arterial hypertension and 44 healthy controls (HCs) underwent 3 Tesla contrast-enhanced cardiovascular MRI, including T1 mapping and quantitative stress perfusion. High-sensitivity troponin I and N-terminal pro-brain natriuretic peptide were also measured.

RESULTS

Cardiovascular MRI revealed a lower myocardial perfusion reserve in the SSc patients compared with HCs {median (interquartile range (IQR)] 1.9 (1.6-2.4) vs 3 (2-3.6), P < 0.001}. Late gadolinium enhancement, indicating focal fibrosis, was observed in 17/83 patients but in none of the HCs, with significantly higher extracellular volume (ECV), suggestive of diffuse fibrosis, in SSc vs HC [mean (s.d.) 31 (4) vs 25 (2), P < 0.001]. Presence of late gadolinium enhancement and higher ECV was associated with skin score [odds ratio (OR) = 1.115, P = 0.048; R2 = 0.353, P = 0.004], and ECV and myocardial perfusion reserve was associated with the presence of digital ulcers at multivariate analysis (R2 = 0.353, P < 0.001; R2 = 0.238, P = 0.011). High-sensitivity troponin I was significantly higher in patients with late gadolinium enhancement, and N-terminal pro-brain natriuretic peptide was associated with ECV (P < 0.05).

CONCLUSION

Subclinical SSc-pHI is characterized by myocardial microvasculopathy, diffuse and focal myocardial fibrosis but preserved myocardial contractile function. This subclinical phenotype of SSc-pHI was associated with high-sensitivity troponin I, N-terminal pro-brain natriuretic peptide, SSc disease severity and complicated peripheral vasculopathy. These data provide information regarding the underlying pathophysiological processes and provide a basis for identifying individuals at risk of SSc-pHI.

Determinants and prognostic value of cardiac magnetic resonance imaging-derived infarct characteristics in non-ST-elevation myocardial infarction

Aims

The prognostic significance of cardiac magnetic resonance (CMR)-derived infarct characteristics has been demonstrated in ST-elevation myocardial infarction (STEMI) cohorts but is undefined in non-ST-elevation myocardial infarction (NSTEMI) patients. We aimed to investigate determinants and the long-term prognostic impact of CMR imaging-derived infarct characteristics in patients with NSTEMI.

Methods and results

Infarct size (IS), myocardial salvage index (MSI), and microvascular obstruction were assessed using CMR imaging in 284 NSTEMI patients undergoing percutaneous coronary intervention (PCI) in three centres. CMR imaging was performed 3 [interquartile range (IQR) 2–4] days after admission. The primary clinical endpoint was defined as major adverse cardiac events during median follow-up of 4.4 (IQR 3.6–4.9) years. Median IS was 7.2% (IQR 2.2–13.7) of left ventricular (LV) myocardial mass (%LV) and MSI was 65.7 (IQR 39.3–84.9). Age (P ≤ 0.003), heart rate (P ≤ 0.02), the number of diseased coronary arteries (P ≤ 0.01), and Thrombolysis In Myocardial Infarction (TIMI) flow grade before PCI (P &lt; 0.001) were independent predictors of IS and MSI. The primary endpoint occurred in 64 (22.5%) patients. CMR-derived infarct characteristics had no additional prognostic value beyond LV ejection fraction in multivariable analysis.

Conclusion

In this prospective, multicentre NSTEMI cohort reperfused by PCI, age, heart rate, the number of diseased coronary arteries, and TIMI flow grade before PCI were independent predictors of IS and MSI assessed by CMR. However, in contrast to STEMI patients there was no additional long-term prognostic value of CMR-derived infarct characteristics over and above LV ejection fraction.

Clinicaltrials.gov

NCT03516578.

An exploration of the association between ischemic etiology and the likelihood of heart failure hospitalization following cardiac resynchronization therapy

BACKGROUND

Myocardial scarring resulting from cardiomyopathy with ischemic etiology may interfere with effective lead placement during implantation of multi-lead cardioverter-defibrillators for cardiac resynchronization therapy (CRT-D). Extensive scarring is known to be associated with poorer physiological and survival outcomes in patients who undergo CRT-D.

HYPOTHESIS

Ischemic CRT-D recipients respond as well as nonischemic recipients, using hospital admission for heart failure (HF) as a measure of response.

METHODS

Patients who underwent CRT-D between February 1, 2013, and February 1, 2014, were identified in an insurer's claims. Inclusion required 1 year of enrollment pre- and post-CRT-D. The sample was divided into nonischemic and ischemic groups, and a subset of the ischemic group with a history of ST-segment elevation myocardial infarction (STEMI) was identified. The likelihood of HF hospital admissions in the year before and after CRT-D was computed for each group, as well as for the subset of patients with HF admissions prior to CRT-D.

RESULTS

A significant (P = 0.02) association was found between ischemic etiology and the post-CRT-D HF admission likelihood. No association was found between history of STEMI vs nonischemic status and likelihood of post-CRT-D HF admission. All groups had significantly lower risk of HF admissions after CRT-D. None of the comparisons involving only patients with a HF hospitalization in the year prior to CRT-D were significant.

CONCLUSIONS

Patients with nonischemic etiology were significantly less likely to experience a HF admission after CRT-D, but the risk of HF admission improved significantly in all groups after CRT-D.

Pathological Q wave as an indicator of left ventricular ejection fraction in acute myocardial infarction

Background: Q-wave myocardial infarction (QMI) has higher mortality and lower myocardial viability than non-Q-wave myocardial infarction (NQMI), suggesting the existence of pathological Q waves reflects the worse ventricular function. The aim of the study is to determine difference in left ventricular ejection fraction (LVEF) between QMI and NQMI.Methods: The study design was cross-sectional analysis conducted in patients with AMI that were hospitalized and undergone echocardiography in Abdul Wahab Sjahranie County General Hospital Samarinda during February 2014 to March 2015. Standard 12-lead electrocardiograms (ECG) were recorded at presentation, 1 day and 2 days after the onset of AMI as well as using the classical criteria for pathological Q wave. LVEF assessment was performed using echocardiography after the second day since the onset of AMI. Independent-T test was used to determine difference in LVEF using PSPPIRE 0.8.4.Results: There were 34 subjects comprising 16 QMI patients and 18 NQMI patients.  QMI had a lower LVEF (42±13%) compared to NQMI (60±11%, p<0.001). The presence of pathological Q waves was associated with LVEF ≤40% (p=0.002).Conclusion: QMI had a lower LVEF than NQMI, provides information about the role of pathological Q wave as an indicator of LVEF.

Microvascular Obstruction Evaluation Using Cardiovascular Magnetic Resonance (CMR) in ST-Elevated Myocardial Infarction (STEMI) Patients

BACKROUND

Restoration of blood flow in epicardial coronary artery in patients with acute myocardial infarction can, but does not have to restore efficient blood flow in coronary circulation. The aim of the study was a direct comparison of microvascular obstruction (MVO) detected by rest and stress perfusion imaging and gadolinium enhancement obtained 2 min. (early MVO) and 15 min. (delayed MVO) post contrast.

MATERIAL/METHODS

106 patients with first anterior myocardial infarction were studied. Cardiovascular magnetic resonance (CMR) was performed 5±2 days after primary percutaneous coronary intervention (pPCI). Stress and rest perfusion imaging was performed as well as early and delayed gadolinium enhancement and systolic function assessment. Scoring of segmental function, perfusion defect, MVO and scar transmurality was performed in 16 segment left ventricular model.

RESULTS

The prevalence of MVO varies significantly between imaging techniques ranging from 48.8% for delayed MVO to 94% with stress perfusion. Median sum of scores was significantly different for each technique: stress perfusion 13 (7; 18), rest perfusion 3 (0.5; 6), early MVO 3 (0; 8), delayed MVO 0 (0; 4); p<0.05. Infarct size, stress and rest perfusion defects were independent predictors of LV EF at discharge from hospital.

CONCLUSIONS

Imaging protocol has a significant impact on MVO results. The study is the first to describe a stress-induced MVO in STEMI patients. Further research is needed to evaluate its impact on a long term prognosis.

Usefulness of cardiac MRI in the prognosis and follow-up of ischemic heart disease

Cardiac magnetic resonance imaging (MRI) is an important tool that makes it possible to evaluate patients with cardiovascular disease; in addition to infarction and alterations in myocardial perfusion, cardiac MRI is useful for evaluating other phenomena such as microvascular obstruction and ischemia. The main prognostic factors in cardiac MRI are ventricular dysfunction, necrosis in late enhancement sequences, and ischemia in stress sequences. In acute myocardial infarction, cardiac MRI can evaluate the peri-infarct zone and quantify the size of the infarct. Furthermore, cardiac MRI's ability to detect and evaluate microvascular obstruction makes it a fundamental tool for establishing the prognosis of ischemic heart disease. In patients with chronic ischemic heart disease, cardiac MRI can detect ischemia induced by pharmacological stress and can diagnose infarcts that can be missed on other techniques.

Electrocardiographic Q-wave "remodeling" in reperfused ST-segment elevation myocardial infarction: validation study with CMR

OBJECTIVES

The aim of this study was to evaluate the evolution in Q-wave expression during the first 5 years after a primary, successfully reperfused ST-segment elevation myocardial infarction (MI), using cardiac magnetic resonance (CMR) for infarct location, and to depict changes in infarct size and left ventricular remodeling over time.

BACKGROUND

In the absence of QRS confounders, abnormal Q waves are usually diagnostic of myocardial necrosis. It is hypothesized that Q-wave regression after MI could be related to smaller infarct sizes. Late gadolinium enhancement accurately depicts MI of any age.

METHODS

Forty-six MI patients underwent electrocardiography and CMR at 1 week (baseline), 4 months, 1 year, and 5 years post-infarction. Conventional CMR parameters were analyzed, and infarct presence, location, and size were assessed using late gadolinium enhancement CMR. Infarct locations were anterior or nonanterior (inferior and/or lateral), using late gadolinium enhancement CMR as a reference. For each time point, patients were classified as having a diagnostic/nondiagnostic electrocardiogram (ECG) using the European Society of Cardiology/American College of Cardiology Foundation/American Heart Association/World Heart Federation consensus criteria for previous Q-wave infarct.

RESULTS

At baseline, 11 patients (23%) did not meet the criteria for Q-wave MI. Non-Q-wave infarcts were significantly smaller than Q-wave infarcts (p < 0.0001). All anterior Q-wave infarcts (n = 17) were correctly localized, whereas in 7 of 19 nonanterior Q-wave infarcts, the location or extent of the infarct was misjudged by electrocardiography. At 4-month/1-year follow-up, in 10 patients (3 anterior/7 nonanterior), the ECG became nondiagnostic. The ECG remained nondiagnostic at 5-year follow-up. A cutoff infarct size of 6.2% at 1 year yielded a sensitivity of 89% and a specificity of 74% to predict the presence or absence of Q waves.

CONCLUSIONS

The incidence of nondiagnostic ECGs for previous MI using the current European Society of Cardiology/American College of Cardiology Foundation/American Heart Association/World Heart Federation criteria is substantial and increases with time post-infarction from 23% immediately post-infarction to 44% at 5-year follow-up.

Allograft coronary artery thrombosis: a case report of early cardiac allograft left ventricular myocardial infarction

Cardiac allograft dysfunction is a major cause of morbidity and mortality in the early post-transplantation period. This is a critical condition that requires prompt diagnosis and management. We present the case of a 57-year-old man with ischemic cardiomyopathy who underwent cardiac transplantation and developed a rare case of coronary artery thrombosis in the setting of heparin-induced thrombocytopenia and thrombosis syndrome (HITTS) within the first 2 postoperative weeks. Transmural myocardial infarction (MI) was initially noted on cardiac magnetic resonance (CMR) imaging as regional left ventricular wall motion abnormalities and transmural hyperenhancement after gadolinium administration, prompting further evaluation of the coronary circulation with angiography.

Global and regional longitudinal strain assessed by two-dimensional speckle tracking echocardiography identifies early myocardial dysfunction and transmural extent of myocardial scar in patients with acute ST elevation myocardial infarction and relatively preserved LV function

AIMS

Global and regional longitudinal strain (GLS-RLS) assessed by two-dimensional speckle tracking echocardiography (2D-STE) are considered reliable indexes of left-ventricular (LV) function and myocardial viability in chronic ischaemic patients when compared with delayed-enhanced cardiac magnetic resonance (DE-CMR). In the present study, we tested whether GLS and RLS could also identify early myocardial dysfunction and transmural extent of myocardial scar in patients with acute ST elevation myocardial infarction (STEMI) and relatively preserved LV function.

METHODS AND RESULTS

Twenty STEMI patients with LVEF ≥40%, treated with PPCI within 6 h from symptoms onset, underwent DE-CMR and 2D-echocardiography for 2D-STE analysis 6 ± 2 days after STEMI. Wall motion score index (WMSI) and LV ejection fraction (LVEF) were calculated by both methods. Infarct size and transmural extent of necrosis were assessed by CMR. GLS and RLS were obtained by 2D-STE. Mean GLS of the study population was -14 ± 3.3, showing a significant correlation with both LVEF and WMSI, by CMR (r = -0.86, P = 0.001, and r = 0.80, P = 0.001, respectively) and time-to-PCI (r = 0.66, P = 0.038). A weaker correlation was found between GLS and LVEF and WMSI assessed by 2D-echo (r = -0.65, P = 0.001, and r = 0.53, P = 0.013, respectively). RLS was significantly lower in DE-segments when compared with normal myocardium (P < 0.0001). A cut-off value of RLS of -12.3% by receiver-operating characteristic (ROC) curves identified DE-segments (sensitivity 82%, specificity 78%), whereas a cut-off value of -11.5% identified transmural extent of DE (sensitivity 75%, specificity 78%).

CONCLUSION

Our findings indicate that RLS and GLS evaluation provides an accurate assessment of global myocardial function and of the presence of segments with transmural extent of necrosis, with several potential clinical implications.

Effects of atorvastatin pretreatment on infarct size in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

BACKGROUND

Atorvastatin pretreatment has been reported to reduce myocardial damage in patients undergoing percutaneous coronary intervention (PCI). We sought to investigate the effect of atorvastatin pretreatment on infarct size in patients with ST-segment elevation myocardial infarction (STEMI).

METHODS

Patients undergoing primary PCI for ST-segment elevation myocardial infarction within 12 hours after symptom onset were randomized to an atorvastatin group (80 mg before PCI and for 5 days after PCI [n = 89]) or a control group (10 mg daily after PCI [n = 84]). The primary end point was infarct size measured by technetium Tc 99m tetrofosmin single-photon emission computed tomography between days 5 and 14.

RESULTS

Baseline clinical, angiographic, and procedural characteristics were not significantly different between groups except for age and current smoking status. There was no significant difference in infarct size (as a percentage of the left ventricle) between groups (22.2% ± 15.5% in the atorvastatin group vs 21.6% ± 15.4% in the control group, P = .79). The median infarct size was 19.0% (interquartile range 9.0-32.0) in the atorvastatin group and 18.0% (9.3-32.5) in the control group (P = .76). Achievement of myocardial blush grade 2/3 and complete ST-segment resolution at 60 minutes after PCI occurred with similar frequency (72.8% vs 81.9%, P = .33 and 43.2% vs 47.5%, P = .57, respectively).

CONCLUSIONS

Pretreatment with high-dose atorvastatin followed by further treatment for 5 days did not reduce infarct size measured by single-photon emission computed tomography in patients undergoing primary PCI.

Cardiac magnetic resonance imaging in ischemic heart disease: a clinical review

Cardiac magnetic resonance imaging (MRI) has emerged as a prime player in the clinical and preclinical detection of ischemic heart disease (IHD) as well in the prognosis assessment by offering a comprehensive approach for all spectrums of coronary artery disease (CAD) patients. The aim of this review is to provide the reader a state-of-the art on how the newest cardiac MRI techniques can be used to study IHD patients. In patients with suspected/stable CAD, functional and perfusion imaging both at rest and during vasodilatatory stress (adenosine, dypiridamole)/dobutamine stress can accurately depict ischemic myocardium secondary to significant coronary artery stenosis. In patients with acute MI, MRI is a robust tool for differentiating and sizing the jeopardized and the infarcted myocardium by using a combination of functional, edema, perfusion and Gd contrast imaging. Moreover, important prognostic factors like myocardial salvage, the presence of microvascular obstruction (MVO), post reperfusion myocardial hemorrhage, RV involvement and infarct related complications can be assessed in the same examination. In patients with chronic ischemic cardiomyopathy, the role of the MRI extends from diagnosis by means of Gadolinium contrast scar imaging to therapy and prognosis by functional assessment and viability testing with rest and dobutamine stress imaging. In all the circumstances mentioned, MRI derived information has been proven valuable in every day clinical decision making and prognosis assessment. Thus, MRI is becoming more and more an accepted alternative to other imaging modalities both in the acute and chronic setting.

Comparison of magnetic resonance imaging findings in non-ST-segment elevation versus ST-segment elevation myocardial infarction patients undergoing early invasive intervention

To define causes and pathological mechanisms underlying differences in clinical outcomes, we compared the findings of contrast-enhanced magnetic resonance imaging (CE-MRI) between ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation myocardial infarction (NSTEMI). In 168 patients undergoing early invasive intervention for STEMI (n = 113) and NSTEMI (n = 55), CE-MRI was performed a median of 6 days after the index event. Infarct size was measured on delayed-enhancement imaging, and area at risk (AAR) was quantified on T2-weighted images. The median infarct size was significantly smaller in the NSTEMI group than in the STEMI group (10.7% [5.6-18.1] vs. 19.2% [10.3-30.7], P < 0.001). Although there was a trend toward a greater myocardial salvage index ([AAR - infarct size] × 100/AAR) in the NSTEMI group compared to the STEMI group (48.2 [30.4-66.8] vs. 40.5 [24.8-53.5], P = 0.056), myocardial salvage index was similar between the groups in patients with anterior infarction (39.6 [20.0-54.9] vs. 35.5 [23.2-53.4], P = 0.96). The NSTEMI group also had a significantly lower extent of microvascular obstruction and a smaller number of segments with >75% of infarct transmurality relative to the STEMI group (0% [0-0.6] vs. 0.9% [0-2.3], P < 0.001 and 3.0 ± 2.3 vs. 4.6 ± 2.9, P = 0.001, respectively). Myocardial hemorrhage was detected less frequently in the NSTEMI group than the STEMI group (22.6% vs. 43.8%, P = 0.029). In the multivariate analysis, baseline Thrombolysis In Myocardial Infarction flow grade 3 and hemorrhagic infarction were closely associated with ST-segment elevation (OR 0.32, 95% CI 0.13-0.81, P = 0.017; OR 5.66, 95% CI 1.77-18.12, P = 0.003, respectively). In conclusion, in vivo pathophysiological differences revealed by CE-MRI assessment include more favorable infarct size, AAR, myocardial salvage and reperfusion injury in patients with NSTEMI compared to those with STEMI undergoing early invasive intervention.

First-pass perfusion CMR two days after infarction predicts severity of functional impairment six weeks later in the rat heart

BACKGROUND

In humans, dynamic contrast CMR of the first pass of a bolus infusion of Gadolinium-based contrast agent has become a standard technique to identify under-perfused regions of the heart and can accurately demonstrate the severity of myocardial infarction. Despite the clinical importance of this method, it has rarely been applied in small animal models of cardiac disease. In order to identify perfusion delays in the infarcted rat heart, here we present a method in which a T1 weighted MR image has been acquired during each cardiac cycle.

METHODS AND RESULTS

In isolated perfused rat hearts, contrast agent infusion gave uniform signal enhancement throughout the myocardium. Occlusion of the left anterior descending coronary artery significantly reduced the rate of signal enhancement in anterior regions of the heart, demonstrating that the first-pass method was sensitive to perfusion deficits. In vivo measurements of myocardial morphology, function, perfusion and viability were made at 2 and 8 days after infarction. Morphology and function were further assessed using cine-MRI at 42 days. The perfusion delay was larger in rat hearts that went on to develop greater functional impairment, demonstrating that first-pass CMR can be used as an early indicator of infarct severity. First-pass CMR at 2 and 8 days following infarction better predicted outcome than cardiac ejection fraction, end diastolic volume or end systolic volume.

CONCLUSION

First-pass CMR provides a predictive measure of the severity of myocardial impairment caused by infarction in a rodent model of heart failure.

Acute chest pain: the role of MR imaging and MR angiography

MR imaging (MRI) and MR angiography (MRA) have gained a high level of diagnostic accuracy in cardiovascular disease. MRI in cardiac disease has been established as the non-invasive standard of reference in many pathologies. However, in acute chest pain the situation is somewhat special since many of the patients presenting in the emergency department suffer from potentially life-threatening disease including acute coronary syndrome, pulmonary embolism, and acute aortic syndrome. Those patients need a fast and definitive evaluation under continuous monitoring of vital parameters. Due to those requirements MRI seems to be less suitable compared to X-ray coronary angiography and multislice computed tomography angiography (CTA). However, MRI allows for a comprehensive assessment of all clinically stable patients providing unique information on the cardiovascular system including ischemia, inflammation and function. Furthermore, MRI and MRA are considered the method of choice in patients with contraindications to CTA and for regular follow-up in known aortic disease. This review addresses specific features of MRI and MRA for different cardiovascular conditions presenting with acute chest pain.

Imaging as an End Point in Ischemia Trials

Imaging of cardiac function and anatomy has advanced at an exponential rate over the past two decades. Our ability to quantitatively assess the degree of myocardial ischemia and accurately define the vascular anatomy using noninvasive techniques is greater than ever before. Current advances is cardiac imaging are allowing us to more safely assess patients for myocardial ischemia and better understand the prognostic implications of our findings. This review summarizes the current state of knowledge in cardiac imaging for the assessment of cardiac ischemia with a focus on the use of cardiac MRI.

Anatomical and functional evaluation of the myocardium in patients with acute coronary syndrome (NSTEMI) using MR imaging

PURPOSE

The aim of our study was to evaluate the role of magnetic resonance (MR) imaging in identifying the location and extent of acute ischaemic injury to predict reversibility and distinguish areas of acute from chronic ischaemia in patients with acute coronary syndrome non- ST-elevation myocardial infarction (NSTEMI).

MATERIALS AND METHODS

We evaluated 22 patients with NSTEMI acute coronary syndrome confirmed by coronary angiography (CA). We studied ventricular function indices and segmental changes in wall thickness and kinetics by cine-MR imaging sequences. Subsequently, we evaluated myocardial wall oedema with T2-weighted black-blood short-tau inversion recovery turbo spin echo (T2 BB-STIRTSE) sequences and identified areas of myocardial necrosis using T1-weighted turbo field-echo inversion recovery (T1 TFE-IR) sequences after contrast material administration.

RESULTS

The results obtained with the single sequences were as follows: T2 BB-STIR-TSE: 96.8% sensitivity, 100% specificity, 99.7% negative predictive value, 99.7% positive predictive value; T1 TFE-IR: 45.8% sensitivity, 96.9% specificity, 92.3% negative predictive value, 90.3% positive predictive value; systolic wall thickening: 87.5% sensitivity, 91.8% specificity, 98.7% negative predictive value, 50% positive predictive value, 91.4% accuracy.

CONCLUSIONS

Our study suggests that the sequences used for evaluating oedema and assessing viability allow for precise localisation and differentiation of areas of acute and chronic ischaemia by quantifying the possible mismatch between ischaemia and necrosis.

CMR for characterization of the myocardium in acute coronary syndromes

The utility of cardiac magnetic resonance imaging (CMR) as a diagnostic technique is well established. CMR enables tissue characterization, distinction between myocardial scar tissue and viable tissue, and evaluation of myocardial perfusion and contractile function. To date, CMR has been mostly applied in the assessment of stable disease; however, a role for CMR in the acute setting is also emerging. An accurate appraisal of the myocardium with CMR in the first hours after the onset of chest pain could provide supporting information to standard diagnostic tools, such as electrocardiography and measurement of blood biomarkers, which could help guide the selection of appropriate treatment. The aims of this integrated approach include positive identification of an ischemic syndrome, estimation of downstream areas at risk of damage, evaluation of epicardial artery patency and small vessel integrity, quantification of infarct size, and determination of myocardial function. This Review critically evaluates both established and emerging CMR techniques, and relates the imaging findings to the underlying pathophysiological processes in acute coronary syndromes. A more thorough understanding of CMR techniques will clarify their potential clinical applications and limitations, and assess the practicality of CMR in the setting of acute coronary syndromes, where early intervention is crucial to save myocardium at risk of irreversible injury.

Review of Journal of Cardiovascular Magnetic Resonance 2009

There were 56 articles published in the Journal of Cardiovascular Magnetic Resonance in 2009. The editors were impressed with the high quality of the submissions, of which our acceptance rate was about 40%. In accordance with open-access publishing, the articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. We have therefore chosen to briefly summarise the papers in this article for quick reference for our readers in broad areas of interest, which we feel will be useful to practitioners of cardiovascular magnetic resonance (CMR). In some cases where it is considered useful, the articles are also put into the wider context with a short narrative and recent CMR references. It has been a privilege to serve as the Editor of the JCMR this past year. I hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality manuscripts to JCMR for publication.