Infarcted Segments Research Articles

The Impact of Infarct Location and Extent on LV Motion Patterns: Implications for Dyssynchrony Assessment

ObjectivesThis study sought to investigate the influence of scar extent and location on the motion pattern of the left ventricle (LV) and its interaction with LV conduction delays. BackgroundDifferent echocardiographic parameters have been proposed to identify responders to cardiac resynchronization therapy based on the detection of LV mechanical dyssynchrony. However, the impact of infarct scar on the diagnostic performance of these parameters remains unknown. MethodsWe included 11 healthy volunteers and 122 patients with normal and severely reduced function, wide and narrow QRS, as well as with and without infarct scar. Location and extent of infarct scar was defined by contrast-enhanced cardiac magnetic resonance. Influence of infarct scar on the motion pattern of the LV was examined by measuring direction and amplitude of apical rocking. The influence of scar on different echocardiographic dyssynchrony parameters was investigated. ResultsScar in the absence of conduction delay caused most apical rocking in the presence of 3 to 4 infarct segments. Pure apical infarction caused no rocking. In wide QRS patients without infarct scar, apical rocking was mainly dominated by the conduction delay, whereas in wide QRS patients with ischemic cardiomyopathy, this pattern was modulated by the scar. Apical rocking was inversely related to scar extent (r = −0.54, p < 0.05). Apical rocking was better associated with cardiac resynchronization therapy response than conventional dyssynchrony measurements. ConclusionsLV motion patterns are mainly dominated by conduction delays, but they are also modulated by infarct scar. Higher scar burden resulted in less pronounced apical rocking. Apical rocking is more strongly associated with cardiac resynchronization therapy response than with conventional echocardiographic parameters and may therefore be used as a screening parameter.

Delayed coronary surgery for the treatment of acute myocardial infarction with elevated ST segment

To develop algorithms of reperfusion therapy (RT) based on the assessment of the initial risk of death determining the priority use of delayed transdermal coronary surgery (TCS) unavailable in the early period. We compared effectiveness of different strategies for the treatment of 1245 patients with acute myocardial infarction (MI) and elevated ST segment in 2003-2007 including various TCS modalities at recommended time (n = 88), delayed TCS within 24-72 hr after the onset of MI (n = 194), thrombolytic therapy without subsequent TCS (n = 275), and conservative therapy (N = 688). The general and cardiovascular lethality was evaluated among 474 patients 5 years after discharge. The results suggest that unavailability of TCS in recommended time in case of enhanced risk of death does not exclude the possibility of its delayed application. TCS 24-72 hr after the onset of MI prevents complications and the fatal outcome the frequency of which remains high remains high not only in the early but also in the late post-infarction period. Delayed TCS can be effectively used to treat patients in case of their late admission or referral from other hospitals where X-ray endovascular methods for the treatment of acute MI are not used.

Prognostic Value of QRS Fragmentation in Patients with Acute Myocardial Infarction: A Meta-Analysis.

Fragmented QRS has emerged as a novel electrocardiographic parameter associated with adverse clinical events in various diseases. The aim of this study was to investigate the association of fQRS with in-hospital and long-term cardiovascular events in patients with ST-segment elevation myocardial infarction (STEMI) and non-ST segment elevation myocardial infarction (NSTEMI). We searched PubMed, Embase, Web of Science, and Cochrane Library up to October 2015 for eligible studies. We selected studies with fQRS defined with 12-lead ECG during the index hospitalization of STEMI/NSTEMI. Primary outcomes were in-hospital and long-term cardiovascular events. In-hospital mortality was significantly higher in fQRS (+) group (99/733; 13.5%) compared to fQRS (-) group (47/1293; 3.6%) (OR 4.03 95% CI 1.81-8.94; P = 0.0006). Long-term mortality rate was higher in fQRS (+) group (89/473; 18.8%) compared to fQRS (-) group (54/1009; 5.3%) (OR 3.93 95% CI 1.92-8.05; P = 0.0002). In addition the frequency of long-term MACE was higher in fQRS (+) group (46.9%) compared to fQRS (-) group (14.6%) (OR 5.13 95% CI 2.77-9.51; P < 0.00001) CONCLUSION: Presence of fQRS on admission ECG was found to be predictor of mortality, MACE, deterioration of LV function, and presence of multivessel disease in patients with STEMI and NSTEMI.

Segmentation of Hyperacute Cerebral Infarcts Based on Sparse Representation of Diffusion Weighted Imaging

Segmentation of infarcts at hyperacute stage is challenging as they exhibit substantial variability which may even be hard for experts to delineate manually. In this paper, a sparse representation based classification method is explored. For each patient, four volumetric data items including three volumes of diffusion weighted imaging and a computed asymmetry map are employed to extract patch features which are then fed to dictionary learning and classification based on sparse representation. Elastic net is adopted to replace the traditional L 0-norm/L 1-norm constraints on sparse representation to stabilize sparse code. To decrease computation cost and to reduce false positives, regions-of-interest are determined to confine candidate infarct voxels. The proposed method has been validated on 98 consecutive patients recruited within 6 hours from onset. It is shown that the proposed method could handle well infarcts with intensity variability and ill-defined edges to yield significantly higher Dice coefficient (0.755 ± 0.118) than the other two methods and their enhanced versions by confining their segmentations within the regions-of-interest (average Dice coefficient less than 0.610). The proposed method could provide a potential tool to quantify infarcts from diffusion weighted imaging at hyperacute stage with accuracy and speed to assist the decision making especially for thrombolytic therapy.

Targeted Transthoracic Acoustic Activation of Systemically Administered Nanodroplets to Detect Myocardial Perfusion Abnormalities.

Liquid core nanodroplets containing condensed gaseous fluorocarbons can be vaporized at clinically relevant acoustic energies and have been hypothesized as an alternative ultrasound contrast agent instead of gas-core agents. The potential for targeted activation and imaging of these agents was tested with droplets formulated from liquid octafluoropropane (C3) and 1:1 mixtures of C3 with liquid decafluorobutane (C3C4). In 8 pigs with recent myocardial infarction and variable degrees of reperfusion, transthoracic acoustic activation was attempted using 1.3 to 1.7 MHz low (0.2 mechanical index [MI]) or high MI (1.2 MI) imaging in real time (32-64 Hertz) or triggered 1:1 at end systole during a 20% C3 or C3C4 droplet infusion. Any perfusion defects observed were measured and correlated with delayed enhancement magnetic resonance imaging and postmortem staining. No myocardial contrast was produced with any imaging setting when using C3C4 droplets or C3 droplets during low MI real-time imaging. However, myocardial contrast was observed in all 8 pigs with C3 droplets when using triggered high MI imaging and in 5 of 6 pigs that had 1.7 MHz real time-high MI imaging. Although quantitative myocardial contrast was lower with real-time high MI imaging than 1:1 triggering, the correlation between real-time resting defect size and infarct size was good (r=0.97; P<0.001), as was the correlation with number of transmural infarcted segments by delayed enhancement imaging. Targeted transthoracic acoustic activation of infused intravenous C3 nanodroplets is effective, resulting in echogenic and persistent microbubbles which provide real-time high MI visualization of perfusion defects.

Myocardial Infarct Segmentation From Magnetic Resonance Images for Personalized Modeling of Cardiac Electrophysiology.

Accurate representation of myocardial infarct geometry is crucial to patient-specific computational modeling of the heart in ischemic cardiomyopathy. We have developed a methodology for segmentation of left ventricular (LV) infarct from clinically acquired, two-dimensional (2D), late-gadolinium enhanced cardiac magnetic resonance (LGE-CMR) images, for personalized modeling of ventricular electrophysiology. The infarct segmentation was expressed as a continuous min-cut optimization problem, which was solved using its dual formulation, the continuous max-flow (CMF). The optimization objective comprised of a smoothness term, and a data term that quantified the similarity between image intensity histograms of segmented regions and those of a set of training images. A manual segmentation of the LV myocardium was used to initialize and constrain the developed method. The three-dimensional geometry of infarct was reconstructed from its segmentation using an implicit, shape-based interpolation method. The proposed methodology was extensively evaluated using metrics based on geometry, and outcomes of individualized electrophysiological simulations of cardiac dys(function). Several existing LV infarct segmentation approaches were implemented, and compared with the proposed method. Our results demonstrated that the CMF method was more accurate than the existing approaches in reproducing expert manual LV infarct segmentations, and in electrophysiological simulations. The infarct segmentation method we have developed and comprehensively evaluated in this study constitutes an important step in advancing clinical applications of personalized simulations of cardiac electrophysiology.

Quantitative myocardial perfusion with stress dual-energy CT: iodine concentration differences between normal and ischemic or necrotic myocardium. Initial experience.

To determine whether the quantification of iodine with stress dual-energy computed tomography (DECT-S) allows for the discrimination between a normal and an ischemic or necrotic myocardium using magnetic resonance (MR) as a reference. This retrospective study was approved by the institutional review board, with waiver of informed consent. Thirty-six cardiac MR and DECT-S images from patients with suspected coronary artery disease were evaluated. Perfusion defects were visually determined, and myocardial iodine concentration was calculated by two observers using DECT colour-coded iodine maps. Iodine concentration differences were calculated using parametric tests. Receiver operating characteristic (ROC) curve analysis was conducted to estimate the optimal iodine concentration threshold for discriminating pathologic myocardium. In total, 576 cardiac segments were evaluated. There were differences in mean iodine concentration (p < 0.001) between normal (2.56 ± 0.66mg/mL), ischemic (1.98 ± 0.36mg/dL) and infarcted segments (1.35 ± 0.57mg/mL). A myocardium iodine concentration of 2.1mg/mL represented the optimal threshold to discriminate between normal and pathologic myocardium (sensitivity 75%, specificity 73.6%, area under the curve 0.806). Excellent agreement was found in measured myocardium iodine concentration (intraclass correlation coefficient 0.814). Cardiac DECT-S with iodine quantification may be useful to differentiate healthy and ischemic or necrotic myocardium. • DECT-S allows for determination of myocardial iodine concentration as a quantitative perfusion parameter. • A high interobserver correlation exists in measuring myocardial iodine concentration with DECT-S. • Myocardial iodine concentration may be useful in the assessment of patients with CAD.

Rivaroxaban for Preventing Atherothrombotic Events in People with Acute Coronary Syndrome and Elevated Cardiac Biomarkers: An Evidence Review Group Perspective of a NICE Single Technology Appraisal

As part of its Single Technology Appraisal process, the National Institute for Health and Care Excellence (NICE) invited the company that manufactures rivaroxaban (Xarelto, Bayer) to submit evidence of the clinical and cost effectiveness of rivaroxaban for the prevention of adverse outcomes in patients after the acute management of acute coronary syndrome (ACS). The School of Health and Related Research Technology Appraisal Group at the University of Sheffield was commissioned to act as the independent Evidence Review Group (ERG). The ERG produced a critical review of the evidence for the clinical and cost effectiveness of the technology, based upon the company's submission to NICE. The evidence was derived mainly from a randomised, double-blind, phaseIII, placebo-controlled trial of rivaroxaban (either 2.5 or 5mg twice daily) in patients with recent ACS [unstable angina, non-ST segment elevation myocardial infarction (NSTEMI) or ST segment elevation myocardial infarction (STEMI)]. In addition, all patients received antiplatelet therapy [aspirin alone or aspirin and a thienopyridine either as clopidogrel (approximately 99%) or ticlopidine (approximately 1%) according to national or local guidelines]. The higher dose of rivaroxaban (5mg twice daily) did not form part of the marketing authorisation. A post hoc subgroup analysis of the licensed patients who had ACS with elevated cardiac biomarkers (that is, patients with STEMI and NSTEMI) without prior stroke or transient ischaemic stroke showed that compared with standard care, the addition of rivaroxaban (2.5mg twice daily) to existing antiplatelet therapy reduced the composite endpoint of cardiovascular mortality, myocardial infarction or stroke, but increased the risk of major bleeding and intracranial haemorrhage. However, there were a number of limitations in the evidence base that warrant caution in its interpretation. In particular, the evidence may be confounded because of the post hoc subgroup analysis, modified intention-to-treat analyses, high dropout rates and missing vital status data. Results from the company's economic evaluation showed that the deterministic incremental cost-effectiveness ratio (ICER) for rivaroxaban in combination with aspirin plus clopidogrel or with aspirin alone compared with aspirin plus clopidogrel or aspirin alone was £6203 per quality-adjusted life-year (QALY) gained. In contrast, the ERG's preferred base case estimate was £5622 per QALY gained. The ICER did not rise above £10,000 per QALY gained in any of the sensitivity analyses undertaken by the ERG, although the inflexibility of the company's economic model precluded the ERG from formally undertaking all desired exploratory analyses. As such, only a crude exploration of the impact of additional bleeding events could be undertaken. The NICE Appraisal Committee concluded that the ICERs presented were all within the range that could be considered cost effective and that the results of the ERG's exploratory sensitivity and scenario analyses suggested that the ICER was unlikely to increase to the extent that it would become unacceptable. The Appraisal Committee therefore concluded that rivaroxaban in combination with aspirin plus clopidogrel, or with aspirin alone, was a cost-effective use of National Health Service (NHS) resources for preventing atherothrombotic events in people with ACS and elevated cardiac biomarkers.

Abstract 12943: Assessment of Both Coronary Microvascular Damage and Left Ventricular Chamber Stiffness After Successful Percutaneous Coronary Intervention Predicts Left Ventricular Aneurysm in ST-Segment Elevation Myocardial Infarction

Background: In ST-segment elevation myocardial infarction (STEMI), the short deceleration time of left ventricular (LV) early filling by Doppler is a powerful independent predictor of LV remodeling. On the other hand, recent studies have shown that even if successful reperfusion is achieved in epicardial coronary arteries, microvascular obstruction results in insufficient reperfusion of the infarcted myocardium, leading to LV dysfunction. The purpose of this study was to examine the effects of both microvascular damage and LV chamber stiffness on the risk of LV aneurysm after successful percutaneous coronary intervention (PCI) in STEMI patients. Methods: Two hundred and twenty-one consecutive patients with first anterior STEMI were studied following successful PCI. Microvascular damage was evaluated on the basis of coronary flow velocity patterns using Doppler guidewires. We defined the presence of microvascular obstruction as diastolic deceleration time of ≤600ms and the presence of systolic flow reversal. LV filling patterns were determined by LV inflow pulsed-wave Doppler examination on day 3 after STEMI. Deceleration time ≤130 ms was defined as restrictive. We classified patients into three categories: without restrictive and microvascular obstruction (group 1, n=125), with restrictive or microvascular obstruction (group 2, n= 43), and with restrictive and microvascular obstruction (group 3, n=53). Left ventriculogram obtained 6 months after the infarction was analyzed to measure the LV volume. True LV aneurysm was defined as a deformity of the infarct segment that was apparent during diastole as well as during systole, and demonstrated diastolic contour abnormality. Results: Group 3 was at the highest risk of true LV aneurysm, while group 1 was at the lowest (2/125 [2%], 15/43 [35%], and 30/53 [57%]; P&lt;0.01). The assessment of both examinations was related to the LV volume index at 6 months after the infarction: patients in a poor group had a larger end-diastolic volume index (65±22 vs 91±28 vs 128±31ml/m2; P&lt;0.01). Conclusions: Assessment of both microvascular damage and LV chamber stiffness can accurately predict the risk of LV aneurysm in STEMI patients who underwent successful reperfusion, identifying a subset of high risk patients.

Strain Analysis in the Detection of Myocardial Infarction at the Acute and Chronic Stages

Myocardial ischemia causes contractile dysfunction in ischemic, stunned, and tethered regions with larger infarcted zones having a negative prognostic impact on patients' outcomes. To distinguish the infarcted myocardium from the other regions, we investigated the diagnostic potential of circumferential strain (CS) and radial strain (RS) during the acute and chronic stages of myocardial infarction. Ten pigs underwent 90-minute occlusion of the left anterior descending artery, followed by reperfusion. Echocardiography was performed at baseline, after 90-minute occlusion, and at 2 hours, 30, and 60 days postreperfusion. CS and RS were measured using speckle tracking echocardiography. Subsequently, the pigs were sacrificed, and histological analysis for infarct size was performed. After 90-minute occlusion, reduced strains were detected for all segments (infarcted anterior wall - baseline: CS: -17.6 ± 5.7%, RS: 54.4 ± 16.9%; 90 min: CS: -10.3 ± 3.0%, RS: 23.3 ± 7.0%; tethered posterior wall - baseline: CS: -18.4 ± 3.5%, RS: 68.7 ± 21.1%; 90 min: CS: -10.7 ± 6.4%, RS: 34.5 ± 14.7%, P < 0.001). However, postsystolic shortening was detected only in the infarcted segments, and the time-to-peak CS was 25% longer (P < 0.05). At 30 and 60 days postreperfusion, time-to-peak CS could only detect large scars in the anterior and anterior-septum walls (P < 0.05), while peak CS also detected smaller scars in the lateral wall (P < 0.05). RS failed to distinguish between normal, stunned/tethered, and infarcted myocardium. During occlusion and 2 hours postreperfusion, time-to-peak CS could distinguish between infarcted and stunned/tethered myocardial segments, while at 30 and 60 days postreperfusion, peak CS was the best detector of infarction.

3D harmonic phase tracking with anatomical regularization.

This paper presents a novel algorithm that extends HARP to handle 3D tagged MRI images. HARP results were regularized by an original regularization framework defined in an anatomical space of coordinates. In the meantime, myocardium incompressibility was integrated in order to correct the radial strain which is reported to be more challenging to recover. Both the tracking and regularization of LV displacements were done on a volumetric mesh to be computationally efficient. Also, a window-weighted regression method was extended to cardiac motion tracking which helps maintain a low complexity even at finer scales. On healthy volunteers, the tracking accuracy was found to be as accurate as the best candidates of a recent benchmark. Strain accuracy was evaluated on synthetic data, showing low bias and strain errors under 5% (excluding outliers) for longitudinal and circumferential strains, while the second and third quartiles of the radial strain errors are in the (-5%,5%) range. In clinical data, strain dispersion was shown to correlate with the extent of transmural fibrosis. Also, reduced deformation values were found inside infarcted segments.

Identification of left ventricular systolic dysfunction and contraction inhomogeneity in post-infarction patients using a segmental two-parameter empirical deformable model.

Various computational models have been developed with an objective to mimic the left ventricular (LV) wall motion and establishing global and regional parameters for evaluating cardiac performance. Recently, a segmental two-parameter empirical deformable model was introduced which performs a non-rigid registration to derive contraction and rotational parameters describing the LV motion. In this work, we assessed the capability of the segmental model in identifying the impairment of the LV contraction in the post-infarction patients. The correlation between the contraction parameter, α/repi defined in this work and the total percentage of infarct was investigated. The temporal pattern of the contraction parameter in each LV segment at the mid ventricular slice was also analyzed throughout the systolic cardiac phases. Our results demonstrated that mean α/repi decreased exponentially with an increase in the infarct percentage. While normal subjects showed synchronous contraction for all LV segments, the presence of infarct regions caused LV dyssynchrony, with the infarcted segments demonstrated abnormal contraction patterns.

Thyroid Hormone Profile in Patients With Acute Coronary Syndrome.

Background:Thyroid hormone has the a major role in the cardiovascular system function and cardiac a As well as to maintain the cardiovascular homeostasis A slightly change ind thyroid status actually affects cardiovascular mortality hemodynamic. The background of this study was to define the prevalence of thyroid dysfunction in acute coronary syndrome (ACS).Objectives:The primary objective was to define the prevalence of thyroid dysfunction in acute coronary syndrome, including Non-ST Segment Elevation Myocardial Infarction (NSTEMI), ST-segment Elevation Myocardial Infarction (STEMI), and unstable angina groups. The secondary objective was to determine any associations of thyroids function tests with cardiac catheterization and mortality.Patients and Methods:In a prospective, observational, and cross section study, we enrolled 400 patients admitted at the coronary care unit of King Abdulaziz University Hospital in Jeddah, Saudi Arabia. Venous blood samples were collected from patients for the evaluation of thyroid function (thyroids stimulating hormones, free triiodothyronine, and free thyroxin).Results:Excluding those taking thyroid hormone preparations, 76.7% of patients admitted with acute coronary heart disease (ST-segment elevation myocardial infarction and Non-ST segment elevation myocardial infarction), and unstable angina had euthyroidism. Thyroid dysfunction was reported in 23.3% of patients with coronary heart disease. Overall hypothyroidism prevalence was 7.8%, while subclinical hyperthyroidism in our study was 2.7%. Overt hyperthyroidism and subclinical hyperthyroidism was reported 2.0% and 0.5%, respectively. Euthyroid sick syndrome was noticed in 41 (10.2%) of critically ill patients. The mortality rate was 9.8%; all death patients had low triiodothyronine (T3) syndrome and were associated with statistically significant low free triiodothyronine (FT3) (P > 0.001).Conclusions:No significant variance was observed among patients underwent for cardiac catheterization, STEMI, NSTEMI, unstable angina, and atrial fibrillation with respect to FT4, FT3, and TSH levels during coronary care unit hospitalization based on their profile data.

Analytical performance of high-sensitivity cardiac troponin I detection by VITROS ECIQ with enhanced chemiluminescence method

Objective To evaluate the performances of high-sensitivity cardiac troponin I (cTnI) on VITRO ECIQ with enhanced chemiluminescence method. Methods This verification study validated the limited of detection, function sensitivity, imprecision, linearity of the high-sensitivity cardic troponin used VITROS ECIQ according to the document EP-17A, EP-6A, EP-15A published by Clinical and Laboratory Standards Institute (CLSI) and determined 99th percentiles. All 652 patients with chest pain on immediate admission in TEDA International Cardiovascular Hospital during January to November 2013 were enrolled in this study. Including 323 cases of acute ST segment elevation myocardial infarction and non ST segment elevation myocardial infarction patients as the case group, exclude 329 cases of other diagnosis, 303 cases of apparent normal people as control group. The receiver operating characteristic curve was used to evaluated the sensitivity and the specificity of cTnI. Non-normal distribution of quantitative data were used nonparametric test Mann-Whitney U, With P<0.05 for the difference was statistically significant. Results The LoB was 0.006 5 ng/ml and the LoD was 0.015 5 ng/ml; the FS was 0.016 76 ng/ml; repeatability CV was 1.73 %-2.33 %, reproducibility CV was 4.93%-9.96%.The imprecision were lower than that declared by assay producer. The linearity was 0.015 5-78.4 ng/ml(R2=0.999 9); the 99th percentile reference value was 0.017 ng/ml. The area under the curve(AUC)of cTnI was 0.986, 95%CI 0.973-0.994, with the cut-off value as 0.017 ng/ml, the diagnostic sensitivity and specificity in CIN were 90.09 % and 99.34%. Compared between STEMI and NSTEMI groups after admission, the levels of cTnI had no significantly difference, Z were -0.485, P>0.05; compared between STEMI and control groups after admission, the levels of cTnI had significantly difference, Z were -19.567, P<0.001; compared between NSTEMI and control groups after admission, the levels of cTnI had significantly difference, Z were -14.598, P<0.001. Conclusions High-sensitivity cardiac troponin I detection by VITROS ECIQ with enhanced chemiluminescence method has good performances of sensitivity, linearity, specificity, which meet the clinical needs.(Chin J Lab Med, 2015, 38: 461-465) Key words: Troponin I; Myocardial infarction; Luminescence; Immunoassay; Sensitivity and specificity

Global and regional myocardial deformation mechanics of microvascular obstruction in acute myocardial infarction: a three dimensional speckle-tracking imaging study

Microvascular obstruction (MVO) and transmural infarct size are prognostic factors after acute myocardial infarction (AMI). We assessed the value of myocardial deformation patterns using 3D speckle tracking imaging (3DSTI) in detecting myocardial and microvascular damage after AMI. One hundred patients with first ST-segment elevation MI from the REMI Study were prospectively included. Transthoracic echocardiography with 3DSTI and CMR were performed within 72 h after revascularization therapy. Global (3DG) and segmental (3DS) values of LV longitudinal (LS), circumferential and radial area strain were obtained. Late gadolinium enhancement (LGE) and MVO was quantified as transmural (>50%) or non-transmural (<50%). Predictive performance was assessed by area under the receiver operating curve characteristic (AUC). Mean LVEFCMR was 45.8 ± 9.2 % with 22.2 ± 12.7% transmural LGE. MVO was present in 55 patients (MVO transmural extent 11.4 ± 11.8%). In global analysis, all 3DG strain values were correlated with LVEFCMR and infarct size, with the best correlation obtained for 3DGAS (r = -0.678; p < 0.0001). All 3DG strain values, with the exception of LS, were significantly different between patients with and without MVO. In segmental analysis, all 3DS strain values were significantly lower in transmurally infarcted segments than in non-infarcted segments, and all 3DS values except 3DSRS were significantly lower in non-transmural infarcted segments than in non-infarcted segments. The best 3DS strain for detecting non-viable segments with MVO (MVO > 75%) was 3DSAS [AUC 0.867 (0.849-0.884), 78.0% sensitivity and 81.1% specificity for 3DSAS = -16.1%]. Importantly, 3DSRS and 3DSAS were associated with an increase in diagnostic accuracy of both transmural LGE and MVO over 3DSLS (all increase in AUC > 0.04, all p < 0.01). The newly developed 3DSTI, especially 3DSAS, is a sensitive and reproducible tool to predict and quantify the transmural extent of scar. This new early imaging strategy improve the prediction of MVO while enabling to assess the success of reperfusion and the risk of late systolic remodeling in STEMI.

Quantitative circumferential strain analysis using adenosine triphosphate-stress/rest 3-T tagged magnetic resonance to evaluate regional contractile dysfunction in ischemic heart disease

PurposeWe evaluated whether a quantitative circumferential strain (CS) analysis using adenosine triphosphate (ATP)-stress/rest 3-T tagged magnetic resonance (MR) imaging can depict myocardial ischemia as contractile dysfunction during stress in patients with suspected coronary artery disease (CAD). We evaluated whether it can differentiate between non-ischemia, myocardial ischemia, and infarction. We assessed its diagnostic performance in comparison with ATP-stress myocardial perfusion MR and late gadolinium enhancement (LGE)-MR imaging. MethodsIn 38 patients suspected of having CAD, myocardial segments were categorized as non-ischemic (n=485), ischemic (n=74), or infarcted (n=49) from the results of perfusion MR and LGE-MR. The peak negative CS value, peak circumferential systolic strain rate (CSR), and time-to-peak CS were measured in 16 segments. ResultsA cutoff value of −12.0% for CS at rest allowed differentiation between infarcted and other segments with a sensitivity of 79%, specificity of 76%, accuracy of 76%, and an area under the curve (AUC) of 0.81. Additionally, a cutoff value of 477.3ms for time-to-peak CS at rest allowed differentiation between infarcted and other segments with a sensitivity of 61%, specificity of 91%, accuracy of 88%, and an AUC of 0.75. The differences in CS values between ATP-stress and rest conditions (ΔCS) in non-ischemic segments (median [first quartile, third quartile] −1.7 [−3.2, −0.1] %) were smaller than in segments with ischemia (+1.1 [+0.3, +2.3] %, p<0.001). A cutoff value of +0.3% for the ΔCS value could differentiate segments with ischemia from non-ischemic segments with a sensitivity of 75%, a specificity of 82%, an accuracy of 82%, and an AUC of 0.86. ConclusionsCircumferential strain analysis using tagged MR can quantitatively assess contractile dysfunction in ischemic and infarcted myocardium.

Prognostic value of myocardial T2 mapping post reperfused acute myocardial infarction

Methods Fifty-four patients were enrolled post primary percutaneous coronary intervention (PCI) and underwent CMR on a 1.5T scanner at 48 hours. Myocardial edema was quantified using a T2 mapping technique, while infarct size was assessed via a contrast-enhanced T1-weighted inversion recovery gradient-echo sequence. Information regarding four clinical outcomes: a) mortality, b) repeat myocardial infarction, c) heart failure hospitalization and d) repeat revascularization was collected at 12 months post index primary PCI. Our primary clinical endpoint was a composite of these 4 outcome measures of major adverse cardiovascular events (MACE). The Cox proportional hazards regression model was used to calculate the relative risk of MACE for increased T2 values, adjusted for baseline characteristics related to increased edema (diabetes status, symptom to balloon time, infarct size). Results The mean age was 59.6 ± 8.2 years, 88% were males, 35% were diabetics, 44% were hypertensive. The mean symptom to balloon time was 395 ± 230 minutes and mean door to balloon time was 81.5 ± 39 minutes. The mean T2 value was higher in the infarct segment compared to remote segment (55.1 ± 7.6 ms vs 40.2 ± 2.6 ms, p<0.001). Patients with MACE (n=12) had higher infarct segment T2 values compared to patients that did not (64.4 ± 7.3 ms vs 51.1 ± 5.8 ms, p<0.001). After adjustment for variables associated with increased edema, a T2 value of ≥ 62 ms was associated with a hazard ratio of 1.04 (95% CI:1.01-1.07, p=0.009) for MACE at 12 months (Table 1). Conclusions In reperfused STEMI patients, higher T2 values in the infarct segment are associated with worse prognosis. This suggests the need to develop therapies aimed at reducing myocardial edema post acute myocardial infarction.

Segmentation of Hyper-Acute Ischemic Infarcts from Diffusion Weighted Imaging Based on Support Vector Machine

Accurate and automatic segmentation of hyper-acute ischemic infarct from magnetic resonance imaging is of great importance in clinical trials. Manual delineation is labor intensive, exhibits great variability due to unclear infarct boundaries, and most importantly, is not practical due to urgent time requirement for prompt therapy. In this paper, segmentation of hyper-acute ischemic infarcts from diffusion weighted imaging based on Support Vector Machine (SVM) is explored. Experiments showed that SVM could provide good agreement with manual delineations by experienced experts to achieve an average Dice coefficient of 0.7630.121. The proposed method could achieve significantly higher segmentation accuracy and could be a potential tool to assist clinicians for quantifying hyper-acute infarction and decision making especially for thrombolytic therapy.

The Evaluation of Dual-Energy Myocardial Perfusion Imaging for the Detection of Acute Myocardial Infarction by Using the Second Generation Dual-Source CT in a Porcine Model

Objectives: To evaluate the diagnostic accuracy of “one-step” dual-energy combined coronary CT angiography and first-pass myocardial perfusion imaging for the detection of acute myocardial infarction by using the second generation dual-source CT compared with conventional digital subtraction angiography and histopathological findings in a porcine model. Methods: Five minipigs underwent transcatheter embolization of coronary using gelatin sponge to produce acute myocardial infarction. Arterial-phase myocardial DECT imaging were performed prior to and immediately and 24 hours after the procedure. A colour-coded iodine map was used for evaluation of myocardial perfusion defect using the 17-segment model. Two radiologists in consensus interpreted all iodine map imaging studies at DECT and coronary CT angiography images that were acquired during the DECT-acquisition. Statistical analysis for diagnostic accuracy was performed. Results: Following the coronary embolization, DECT iodine maps showed 45 infarcted segments and 40 non infarcted segments. Based on the per-segment analysis, the sensitivity, specificity, positive predictive value and negative predictive value were 93%, 95%, 95% and 93%, respectively. The corresponding values to per-territory analysis were 100%, 86%, 89% and 100% using histopathological findings as the reference standard. The average dose length product (DLP) was 219.4 ± 60.9 mGy.cm (172-321 mGy.cm). Conclusions: Our experimental study demonstrates that “one-step” dual-energy combined coronary CT angiography and first-pass myocardial perfusion imaging provides high diagnostic accuracy for detecting acute myocardial infarction and a comprehensive image quality of coronary artery with a relatively low dose of radiation in a porcine model.

Clinical experience of strain imaging using DENSE for detecting infarcted cardiac segments.

BackgroundWe hypothesised that myocardial deformation determined with magnetic resonance imaging (MRI) will detect myocardial scar.MethodsDisplacement Encoding with Stimulated Echoes (DENSE) was used to calculate left ventricular strain in 125 patients (29 women and 96 men) with suspected coronary artery disease. The patients also underwent cine imaging and late gadolinium enhancement. 57 patients had a scar area >1 % in at least one segment, 23 were considered free from coronary artery disease (control group) and 45 had pathological findings but no scar (mixed group). Peak strain was calculated in eight combinations: radial and circumferential strain in transmural, subendocardial and epicardial layers derived from short axis acquisition, and transmural longitudinal and radial strain derived from long axis acquisitions. In addition, the difference between strain in affected segments and reference segments, “differential strain”, from the control group was analysed.ResultsIn receiver-operator-characteristic analysis for the detection of 50 % transmurality, circumferential strain performed best with area-under-curve (AUC) of 0.94. Using a cut-off value of -17 %, sensitivity was 95 % at a specificity of 80 %. AUC did not further improve with differential strain. There were significant differences between the control group and global strain circumferential direction (-17 % versus -12 %) and in the longitudinal direction (-13 % versus -10 %). Interobserver and scan-rescan reproducibility was high with an intraclass correlation coefficient (ICC) >0.93.ConclusionsDENSE-derived circumferential strain may be used for the detection of myocardial segments with >50 % scar area. The repeatability of strain is satisfactory. DENSE-derived global strain agrees with other global measures of left ventricular ejection fraction.