Transmural Extent Of Infarction Research Articles

Impact of advanced imaging techniques on cardiac surgery-New insights provided by cardiac magnetic resonance.

This dialog between a cardiac surgeon (C.L.) and cardiac imager (J.W.W.) provides an overview of cardiac MRI (CMR) methods relevant to cardiac surgery. Major areas of focus include logistics of performing a CMR exam, as well as established and emerging methods for assessment of cardiac structure, function, valvular performance, and tissue characterization. Regarding tissue characterization, a major area of focus concerns CMR assessment of viability, for which this modality has been shown to provide incremental utility to conventional techniques for detection of presence and transmural extent of infarction, as well as powerful predictive utility of recovery of left ventricular systolic function as well as long term clinical prognosis in patients with an array of clinical conditions, including coronary artery disease and valvular heart disease both before and following cardiac surgery.

Role of collateral flow in infarct border zone extent and contractile function in patients with chronic coronary total occlusion

PurposeThere is a paucity of data regarding the border zone parameters in patients with chronic coronary total occlusion (CTO). We investigated the border zone extent and contractile function and their associations with collateral flow. MethodsCTO patients (n = 47) and sex- and age-matched volunteers (n = 15) were prospectively enrolled and underwent cardiac MRI examinations to acquire cine and late-gadolinium enhancement (LGE) images. Myocardial peak strain (PS) and the time to PS were determined at the segmental level and global level. Infarct, border zone, adjacent, and remote regions were defined according to the transmural extent of infarction (TEI) by LGE at each segment. Angiographic collateral flow was evaluated using the Rentrop grading system. ResultsCTO patients with well-developed collateral flow had a higher TEI in border zone regions compared to patients with poorly developed collateral flow (p = 0.02). Conversely, CTO patients with poorly developed collaterals showed a higher TEI in infarct regions (p < 0.01). Enhanced border function, characterized by greater PS and earlier time to PS, was noted in well-developed collaterals (all p < 0.05). In the multivariate linear analyses, the level of collateral flow was an independent predictor of the border zone extent (β = 0.40, p = 0.02) and contractile function (radial: β = -0.42, p = 0.02; circumferential: β = 0.39, p = 0.02; and longitudinal: β = 0.47, p < 0.01). ConclusionsIn CTO patients, the presence of well-developed collateral flow was closely linked to a greater extent of LGE and contractile function in border zone regions. Our findings shed light on the cardiac MRI-based pathophysiological underpinning in border zone regions, which could offer complementary and prognostic information in clinical practice.

Assessment of myocardial damage after acute myocardial infarction by diastolic deceleration time of coronary flow velocity using echocardiography and contrast-enhanced magnetic resonance imaging.

There are limited data available regarding the use of diastolic deceleration time (DDT) of three major arteries measured by transthoracic echocardiography (TTE) for assessing coronary microvascular damage after acute myocardial infarction (AMI). Therefore, we aimed to compare the DDT of three major arteries using TTE with the transmural extent of infarction (TEI) and infarct size, which were classified using contrast-enhanced magnetic resonance imaging (CE-MRI), in patients with AMI. The DDT of the culprit coronary artery was measured in 74 patients using TTE and CE-MRI 1week after the onset of AMI. The TEI was graded based on the transmural extent of the hyper-enhanced tissue (grades 1-4). The assessable rate for the DDT was 95%; individual rates were 100% for the left anterior descending coronary artery, 90% for the left circumflex artery, and 93% for the right coronary artery. The DDT decreased gradually as the TEI grade progressed (P=.021). Infarct size was significantly correlated with the DDT (r=-0.51, P<.0001). Univariate analysis revealed that the left ventricular (LV) end-systolic volume, LV ejection fraction, and DDT were significantly associated with TEI grade 4. After adjustment via multiple logistic regression analysis, the DDT was independently remained. With a cutoff value of 950ms, as determined by the ROC curve, DDT could detect TEI grade 4 with 81.1% sensitivity and 80.1% specificity. The DDT of three major coronary arteries measured by TTE 1week after the onset of AMI can assess the extent of myocardial damage, which is determined by CE-MRI.

Assessment of Myocardial Viability After Acute ST- Elevated Myocardial Infarction Using Stress Speckle Tracking Echocardiography and Cardiac MRI

Background: Speckle-tracking echocardiography has emerged as a unique technique for accurately evaluating myocardial function by analyzing the motion of speckles identified. Speckle-tracking measured under stress may offer an opportunity to improve the detection of dynamic regional abnormalities and myocardial viability. Objective: The aim of the current study was to evaluate stress speckle tracking to detect myocardial viability in comparison to cardiac MRI in post-STEMI patients. Patients and methods: 74 patients were prospectively enrolled in 18-month’s study. Dobutamine stress echocardiography was performed 4 days post-infarction accompanied with automated functional imaging analysis of left ventricle during rest and then during low dose stress. All patients underwent a follow up stress echocardiography at 3 months with speckle tracking analysis. Cardiac MRI took place concomitantly at 4 days post-infarction and 3 months. Results: Investigating strain rate obtained with stress speckle tracking after revascularization predicted the extent of myocardial scar, determined by contrast-enhanced magnetic resonance imaging. A good correlation was found between the global strain and total infarct size (R 0.75, p< 0.001). Furthermore, a clear inverse relationship was found between the segmental strain and the transmural extent of infarction in each segment. Meanwhile it provided 81.82% sensitivity and 82.6% specificity to detect transmural from non-transmural infarction at a cut-off value of -10.15. Conclusion: Strain rate obtained from speckle tracking during stress is a novel method of detecting myocardial viability after STEMI. Moreover, it carries a promising role in post-myocardial infarction risk stratification with a reasonable prediction of reversible cardiac-related hospital re-admission.

Interrogation of the infarcted and salvaged myocardium using multi-parametric mapping cardiovascular magnetic resonance in reperfused ST-segment elevation myocardial infarction patients

We used multi-parametric cardiovascular magnetic resonance (CMR) mapping to interrogate the myocardium following ST-segment elevation myocardial infarction (STEMI). Forty-eight STEMI patients underwent CMR at 4 ± 2 days. One matching short-axis slice of native T1 map, T2 map, late gadolinium enhancement (LGE), and automated extracellular volume fraction (ECV) maps per patient were analyzed. Manual regions-of-interest were drawn within the infarcted, the salvaged and the remote myocardium. A subgroup analysis was performed in those without MVO and with ≤75% transmural extent of infarct. For the whole cohort, T1, T2 and ECV in both the infarcted and the salvaged myocardium were significantly higher than in the remote myocardium. T1 and T2 could not differentiate between the salvaged and the infarcted myocardium, but ECV was significantly higher in the latter. In the subgroup analysis of 15 patients, similar findings were observed for T1 and T2. However, there was only a trend towards ECVsalvage being higher than ECVremote. In the clinical setting, current native T1 and T2 methods with the specific voxel sizes at 1.5 T could not differentiate between the infarcted and salvaged myocardium, whereas ECV could differentiate between the two. ECV was also higher in the salvaged myocardium when compared to the remote myocardium.

Role of Myocardial Extracellular Volume Fraction Measured with Magnetic Resonance Imaging in the Prediction of Left Ventricular Functional Outcome after Revascularization of Chronic Total Occlusion of Coronary Arteries.

ObjectiveThe purpose of this study was to prospectively investigate the value of the myocardial extracellular volume fraction (ECV) in predicting myocardial functional outcome after revascularization of coronary chronic total occlusion (CTO).Materials and MethodsThirty patients with CTO underwent cardiovascular magnetic resonance (CMR) before and 6 months after revascularization. Three baseline markers of functional outcome were evaluated in the dysfunctional segments assigned to the CTO vessels: ECV, transmural extent of infarction (TEI), and unenhanced rim thickness (RIM). At the global level, the ECV values of the whole myocardium with and without a hyperenhanced region (global and remote ECV) were respectively measured.ResultsIn per-segment analysis, ECV was superior to TEI and RIM in predicting functional recovery (area under receiver operating characteristic curve [AUC]: 0.86 vs. 0.75 and 0.73, all p values < 0.010), and it emerged as the only independent predictor of regional functional outcome (odds ratio [OR] = 0.83, 95% confidence interval [CI]: 0.77–0.89; p < 0.001) independent of collateral circulation. In per-patient analysis, global baseline ECV was indicative of ejection fraction (EF) at the follow-up examination (β = −0.61, p < 0.001) and changes in EF (β = −0.57, p = 0.001) in multivariate regression analysis. A patient with global baseline ECV less than 30.0% (AUC, 0.93; sensitivity 94%, specificity 80%) was more likely to demonstrate significant EF improvement (OR: 0.38; 95% CI: 0.17–0.85; p = 0.019).ConclusionExtracellular volume fraction obtained by CMR may provide incremental value for the prediction of functional recovery both at the segmental and global levels in CTO patients, and may facilitate the identification of patients who can benefit from revascularization.

Detection of Recent Myocardial Infarction Using Native T1 Mapping in a Swine Model: A Validation Study

Late gadolinium enhancement (LGE) imaging is the currently the gold standard for in-vivo detection of myocardial infarction. However, gadolinium contrast administration is contraindicated in patients with renal insufficiency. We aim to evaluate the diagnostic sensitivity and specificity of this contrast-free MRI technique, native T1 mapping, in detecting recent myocardial infarction versus a reference histological gold standard. Ten pigs underwent CMR at 2 weeks after induced MI. The infarct size and transmural extent of MI was calculated using native T1 maps and LGE images. Histological validation was performed using triphenyl tetrazolium chloride (TTC) staining in the corresponding ex-vivo slices. The infarct size and transmural extent of myocardial infarction assessed by T1 mapping correlated well with that assessed by LGE and TTC images. Using TTC staining as the reference, T1 mapping demonstrated underestimation of infarct size and transmural extent of infarction. Additionally, there was a slight but not significant difference found in the diagnostic performance between the native T1 maps and LGE images for the location of MI. Our study shows that native T1 mapping is feasible alternative method to the LGE technique for the assessment of the size, transmural extent, and location of MI in patients who cannot receive gadolinium contrast.

Redefining viability by cardiovascular magnetic resonance in acute ST-segment elevation myocardial infarction

In chronic myocardial infarction (MI), segments with a transmural extent of infarct (TEI) of ≤50% are defined as being viable. However, in the acute phase of an ST-segment elevation myocardial infarction (STEMI), late gadolinium enhancement (LGE) has been demonstrated to overestimate MI size and TEI. We aimed to identify the optimal cut-off of TEI by cardiovascular magnetic resonance (CMR) for defining viability during the acute phase of an MI, using ≤50% TEI at follow-up as the reference standard. 40 STEMI patients reperfused by primary percutaneous coronary intervention (PPCI) underwent a CMR at 4 ± 2 days and 5 ± 2 months. The large majority of segments with 1–25%TEI and 26–50%TEI that were viable acutely were also viable at follow-up (59/59, 100% and 75/82, 96% viable respectively). 56/84(67%) segments with 51–75%TEI but only 4/63(6%) segments with 76–100%TEI were reclassified as viable at follow-up. TEI on the acute CMR scan had an area-under-the-curve of 0.87 (95% confidence interval of 0.82 to 0.91) and ≤75%TEI had a sensitivity of 98% but a specificity of 66% to predict viability at follow-up. Therefore, the optimal cut-off by CMR during the acute phase of an MI to predict viability was ≤75% TEI and this would have important implications for patients undergoing viability testing prior to revascularization during the acute phase.

Impact of microvascular obstruction on left ventricular local remodeling after reperfused myocardial infarction.

To evaluate by cardiac magnetic resonance imaging (MRI) the impact of microvascular obstruction (MVO) on regional left ventricular (LV) wall characteristics and local remodeling after acute myocardial infarction (AMI). In all, 114 AMI patients underwent cardiac MRI at 3T within 2-4 days (baseline) and at 6 months (follow-up) after reperfusion. Late gadolinium enhancement and cine sequences were performed. The impact of MVO (ie, presence and extent) on regional wall thickening (WT, %), end-diastolic wall thickness (EDWT, mm), and local cavity change (mm) of LV were quantitatively analyzed. Local cavity change, calculated as surface-to-surface distance from registered endocardial surface meshes of cine imaging datasets acquired initially and at follow-up, was used to assess local remodeling. MVO was detected in 69 patients (60.5%). WT was significantly lower when MVO was present (P < 0.05); and it was inversely related to MVO transmural extent (P < 0.0001). WT improvement was significantly worsened when MVO was present in segments with infarct transmural extent exceeding 50%. Significant wall thinning occurred at follow-up in segments with infarct transmural extent >75% with further thinning by MVO presence; and EDWT decreased with increasing MVO transmural extent (P < 0.0001). LV cavity shrank in patients without MVO, whereas it dilated in those with MVO. Local cavity changes were not significantly different by a region-to-region analysis throughout the LV within each group (P = 0.57 and 0.74, respectively). MVO has a significant adverse effect on LV wall characteristics and LV remodeling. Postinfarct remodeling seems to be globally mediated rather than locally mediated during the first 6 months. 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:499-510.

Impact of Plaque Rupture Detected by Optical Coherence Tomography on Transmural Extent of Infarction After Successful Stenting in ST-Segment Elevation Acute Myocardial Infarction

ObjectivesThe aim of the present study was to investigate the association between plaque rupture (PR) assessed by optical coherence tomography (OCT), and the transmural extent of infarction (TEI) assessed by contrast-enhanced cardiac magnetic resonance imaging (CE-CMR) in ST-segment elevation myocardial infarction (STEMI) patients after primary percutaneous coronary intervention (PCI). BackgroundPR is associated with larger infarct size as assessed by cardiac enzymes in STEMI patients. CE-CMR is a favorable method to assess TEI, which can predict the prognosis of STEMI patients. MethodsFirst, STEMI patients with primary PCI within 12 h after onset were enrolled and divided into 2 groups according to presence (n = 71) or absence (n = 32) of PR at the culprit lesion as assessed by pre-intervention OCT. CE-CMR was performed at 1 week after primary PCI. ResultsThe frequency of no-reflow phenomenon (37% vs. 16%; p = 0.032) and distal embolization (24% vs. 6%; p = 0.032) was significantly higher in the rupture group compared with the non-rupture group. TEI grade was significantly greater in the rupture group (28% vs. 15% in grade 3 and 45% vs. 13% in grade 4; p < 0.001). Microvascular obstruction was more frequently seen in the rupture group (39% vs. 19%; p = 0.039). Multivariate analysis identified PR (odds ratio: 6.60, 95% confidence interval: 2.19 to 21.69; p < 0.001) and no statin use before admission (odds ratio: 3.37, 95% confidence interval: 1.06 to 11.19; p = 0.039) as independent predictors of TEI grade 3 or 4. ConclusionsPR as assessed by OCT is associated with greater TEI as assessed by CE-CMR in STEMI patients after primary PCI.

Improved recovery of regional left ventricular function after PCI of chronic total occlusion in STEMI patients: a cardiovascular magnetic resonance study of the randomized controlled EXPLORE trial

BackgroundThe Evaluating Xience and left ventricular function in PCI on occlusiOns afteR STEMI (EXPLORE) trial did not show a significant benefit of percutaneous coronary intervention (PCI) of the concurrent chronic total occlusion (CTO) in ST-segment elevation myocardial infarction (STEMI) patients on global left ventricular (LV) systolic function. However a possible treatment effect will be most pronounced in the CTO territory. Therefore, we aimed to study the effect of CTO PCI compared to no-CTO PCI on the recovery of regional LV function, particularly in the CTO territory.MethodsUsing cardiovascular magnetic resonance (CMR) we studied 180 of the 302 EXPLORE patients with serial CMR (baseline and 4 months follow-up). Segmental wall thickening (SWT) was quantified on cine images by an independent core laboratory. Dysfunctional segments were defined as SWT < 45%. Dysfunctional segments were further analyzed by viability (transmural extent of infarction (TEI) ≤50%.). All outcomes were stratified for randomization treatment.ResultsIn the dysfunctional segments in the CTO territory recovery of SWT was better after CTO PCI compared to no-CTO PCI (ΔSWT 17 ± 27% vs 11 ± 23%, p = 0.03). This recovery was most pronounced in the dysfunctional but viable segments(TEI < 50%) (ΔSWT 17 ± 27% vs 11 ± 22%, p = 0.02). Furthermore in the CTO territory, recovery of SWT was significantly better in the dysfunctional segments in patients with Rentrop grade 2–3 collaterals compared to grade 0–1 collaterals to the CTO (16 ± 26% versus 11 ± 24%, p = 0.04).ConclusionCTO PCI compared with no-CTO PCI is associated with a greater recovery of regional systolic function in the CTO territory, especially in the dysfunctional but viable segments. Further research is needed to evaluate the use of CMR in selecting post-STEMI patients for CTO PCI and the effect of regional LV function recovery on clinical outcome.Trial registrationTrialregister.nl NTR1108, Date registered NTR: 30-okt-2007.

The role of infarct transmural extent in infarct extension: A computational study.

Infarct extension, a process involving progressive extension of the infarct zone (IZ) into the normally perfused border zone (BZ), leads to continuous degradation of the myocardial function and adverse remodelling. Despite carrying a high risk of mortality, detailed understanding of the mechanisms leading to BZ hypoxia and infarct extension remains unexplored. In the present study, we developed a 3D truncated ellipsoidal left ventricular model incorporating realistic electromechanical properties and fibre orientation to examine the mechanical interaction among the remote, infarct and BZs in the presence of varying infarct transmural extent (TME). Localized highly abnormal systolic fibre stress was observed at the BZ, owing to the simultaneous presence of moderately increased stiffness and fibre strain at this region, caused by the mechanical tethering effect imposed by the overstretched IZ. Our simulations also demonstrated the greatest tethering effect and stress in BZ regions with fibre direction tangential to the BZ-remote zone boundary. This can be explained by the lower stiffness in the cross-fibre direction, which gave rise to a greater stretching of the IZ in this direction. The average fibre strain of the IZ, as well as the maximum stress in the sub-endocardial layer, increased steeply from 10% to 50% infarct TME, and slower thereafter. Based on our stress-strain loop analysis, we found impairment in the myocardial energy efficiency and elevated energy expenditure with increasing infarct TME, which we believe to place the BZ at further risk of hypoxia. Copyright © 2016 John Wiley & Sons, Ltd.

Abstract 13561: The Emerging Role of Stress Speckle Tracking in Viability World

Introduction: Speckle-tracking echocardiography has recently emerged as a quantitative ultrasound technique for accurately evaluating myocardial function by analyzing the motion of speckles identified. Speckle-tracking obtained under stress may offer an opportunity to improve the detection of dynamic regional abnormalities and myocardial viability. Objective: To evaluate stress speckle tracking as tool to detect myocardial viability in comparison to cardiac MRI in post-STEMI patients. Methods: 71 patients were prospectively enrolled in our 18-month’s study. Dobutamin stress echocardiography was performed 4 days post-infaction accompanied with automated functional imaging (Speckle tracking) analysis of left ventricle during rest and then during low dose stress. All patients underwent a follow up stress echocardiography at 6 weeks with speckle tracking analysis. Cardiac MRI took place concomitantly at 4 days post-infarction and 6 weeks. We carried out an assessment of re-admission with acute coronary syndrome (ACS) after one year of enrollment. Results: Investigating strain rate obtained with stress speckle tracking after revascularization predicted the extent of myocardial scar, determined by contrast-enhanced magnetic resonance imaging. A good correlation was found between the global strain and total infarct size (R 0.75, p&lt; 0.001). Furthermore, a clear inverse relationship was found between the segmental strain and the transmural extent of infarction in each segment. ( R -0.69, p&lt;0.01). Meanwhile it provided 81.82% sensitivity and 82.6% specificity to detect transmural from non-transmural infaction at a cut-off value of -10.15. Global stress strain rate showed 80% sensitivity and 77.5% specificity at a cut-off value of -9.1 to predict hospital re-admission with ACS. A cut-off value of -8.4 had shown a 69.23% sensitivity and 73.5% specificity to predict the re-admission related to other cardiac symptoms . Conclusion: Strain rate obtained from speckle tracking during stress is a novel method of detecting myocardial viability after STEMI .Moreover it carries a promising role in post-myocardial infarction risk stratification with a reasonable prediction of reversible cardiac-related hospital re-admission.

Evolution of reperfusion post-infarction ventricular remodeling: New MRI insights

BackgroundOur current understanding is that left ventricular (LV) remodeling after acute myocardial infarction (AMI) is caused by expansion of the infarcted myocardium with thinning of the wall and eccentric hypertrophy of the remote myocardium. To study the geometric changes in the remodeling process after reperfused AMI we used cardiac magnetic resonance imaging (CMR). MethodsNine juvenile swine underwent a 120-min occlusion of the left circumflex coronary artery followed by reperfusion. CMR was performed at 3 and 36days post-infarction. Global and regional LV remodeling was assessed including geometric changes of infarcted and remote myocardium; infarct longitudinal length (mm), mean circumferential length (mm), total infarct surface (mm2), end-diastolic wall thickness (EDWT) (mm) and transmural extent of infarction (TEI). ResultsFrom 3days to 36days post-infarction end-diastolic volume increased by 43% (p<0.01). Infarct mass decreased by 36% (p<0.01), mainly by reduction of EDWT with 26%, while mean infarct circumferential length and longitudinal infarct length did not change. Remote myocardial mass increased by 23%, which was the result of an increase in its circumferential length from 95±10mm to 113±11mm (p<0.01), with no change in its EDWT. In contrast, EDWT in the infarct, peri-infarct and border zone decreased. ConclusionsContrary to the widely held view the present, using CMR measurements, shows that post-infarction remodeling was not associated with expansion of the infarcted myocardium. These findings suggest that eccentric hypertrophy of the remote myocardium, but not expansion of the infarct region, is responsible for left ventricular dilatation after AMI.

The Effect of Percutaneous Coronary Intervention of Chronically Totally Occluded Coronary Arteries on Left Ventricular Global and Regional Systolic Function

BackgroundPercutaneous coronary intervention (PCI) is frequently attempted to open chronic total occlusions (CTOs) and restore epicardial coronary flow. Data suggest adverse outcomes in the case of PCI failure. We hypothesized that failure to open a CTO might adversely affect regional cardiac function and promote deleterious cardiac remodelling, and success would improve global and regional cardiac function assessed using cardiac magnetic resonance and velocity vector imaging. MethodsThirty patients referred for PCI to a CTO underwent cardiac magnetic resonance examination before and after the procedure. Left ventricular function and transmural extent of infarction was assessed in these patients. Regional cardiac function using Velocity Vector Imaging version 3.0.0 (Siemens) was assessed in 20 patients. ResultsSuccessful CTO opening (thrombolysis in myocardial infarction 3 flow) occurred in 63% of patients. Left ventricular ejection fraction significantly increased after successful PCI (50 ± 13% to 54 ± 11%; P < 0.01). Global longitudinal strain (GLS) fell significantly in the failed group (Δ = −25 ± 17%; P = 0.02) in contrast with successful PCI in which GLS did not change (Δ 20 ± 32%; P = 0.17). GLS rate followed a pattern similar to GLS (failed, Δ −30 ± 17%; P < 0.01 vs success Δ 25 ± 48%; P = 0.34). In contrast, radial and circumferential strain/strain rate were not different between groups after success/failed PCI. ConclusionsRegional cardiac function assessment using velocity vector imaging showed a significant decline in GLS and GLS rate in patients in whom PCI failed to open a CTO, with no change in global measures of cardiac function.

Deceleration time of diastolic coronary flow velocity as a predictor of transmural extent of infarction in patients with acute myocardial infarction after primary percutaneous coronary intervention

Purpose: The purpose of this study was to investigate whether deceleration time of diastolic coronary flow velocity after primary percutaneous coronary intervention (PCI) can predict the transmural extent of infarction (TEI) defined by contrast-enhanced cardiac magnetic resonance (ce-CMR) in patients with acute myocardial infarction (MI). Methods: In 96 patients after successful PCI for first acute MI, deceleration time of diastolic coronary flow velocity (DDT) were measured by transthoracic echocardiography. Ce-CMR were performed 7 days after onset of acute MI. TEI was graded from 1 to 4 based on the transmural extent of hyperenhanced tissue (grade 1: 0-25% of left ventricular wall thickness, 2: 26-50%, 3: 51-75%, and 4: 76-100%). Infarct size by ce-CMR was also calculated. Results: Adequate recording of DDT were obtained in 92 of 96 patients (96%). Infarct size by ce-CMR and peak creatine kinase-myocardial band values were significantly correlated with DDT (r=0.51, p<0.0001 and (r=0.30, p=0.006, respectively). Moreover, decreased DDT was significantly related to increased TEI-grade (p<0.0001) and existence of microvascular obstruction (p<0.0001). ![Figure][1] Conclusion: DDT measured after primary PCI is a useful predictor for the TEI in patients with acute MI. [1]: pending:yes

092 MICROVASCULAR OBSTRUCTION AND INTRAMYOCARDIAL HAEMORRHAGE INFLUENCES INFARCT ZONE CONTRACTILE RECOVERY IN REPERFUSED ACUTE MYOCARDIAL INFARCTION

IntroductionFollowing acute myocardial infarction (AMI), microvascular obstruction (MO) and intramyocardial haemorrhage (IMH) adversely affect left ventricular (LV) remodelling and prognosis independently of infarct size. The mechanisms by which MO and...

The effect of microvascular obstruction and intramyocardial hemorrhage on contractile recovery in reperfused myocardial infarction: insights from cardiovascular magnetic resonance.

BackgroundFollowing acute myocardial infarction (AMI), microvascular obstruction (MO) and intramyocardial hemorrhage (IMH) adversely affect left ventricular remodeling and prognosis independently of infarct size. Whether this is due to infarct zone remodeling, changes in remote myocardium or other factors is unknown. We investigated the role of MO and IMH in recovery of contractility in infarct and remote myocardium.MethodsThirty-nine patients underwent cardiovascular magnetic resonance (CMR) with T2-weighted and T2* imaging, late gadolinium enhancement (LGE) and myocardial tagging at 2, 7, 30 and 90 days following primary percutaneous coronary intervention for AMI. Circumferential strain in infarct and remote zones was stratified by presence of MO and IMH.ResultsOverall, infarct zone strain recovered with time (p < 0.001). In the presence of MO with IMH and without IMH, epicardial strain recovered (p = 0.03, p < 0.01 respectively), but mid-myocardial or endocardial strain did not (mid-myocardium: p = 0.05, p = 0.12; endocardium: p = 0.27, p = 0.05, respectively). By day 90, infarcts with MO had more attenuated strain in all myocardial layers compared to infarcts without MO (p < 0.01); those with IMH were attenuated further (p < 0.01). Remote myocardial strain was similar across groups at all time-points (p > 0.2). Infarct transmural extent did not correlate with strain (p > 0.05 at each time point). In multivariable logistic regression, MO and IMH were the only significant independent predictors of attenuated 90-day infarct zone strain (p = 0.004, p = 0.011, respectively).ConclusionsStrain improves within the infarct zone overall following reperfusion with or without MO or IMH. Mid-myocardial and endocardial infarct contractility is diminished in the presence of MO, and further in the presence of IMH. MO and IMH are greater independent predictors of infarct zone contractile recovery than infarct volume or transmural extent.

Reverse remodeling after coronary revascularization in patients with ischemic heart disease: focused on change of infarct scar

Background We sought to evaluate the serial change of enhanced necrotic tissue and nonenhanced noninfarct tissue after surgical revascularization in patients with ischemic left ventricular (LV) dysfunction using magnetic resonance (MR) imaging as a quantification tool. Methods Twenty-four patients with severe LV dysfunction {ejection fraction (EF) <35% on echocardiography} underwent before and more than 6 months after surgical revascularization. The following variables were measured: LV volumes, EF, mass, absolute and relative infarction size, transmural extent of infarction, and wall thickness. All patients were classified into two groups: group I, presence of revere remodeling after revascularization; group II, absence of reverse remodeling group. A reduction of 10% or more in end-diastole and end-systole volumes were considered presence of reverse remodeling. Variables were compared between preoperative and postoperative MR scans in each group. Results Of 24, 20 patients showed reverse remodeling. In group I, EF (28.8±6.6% vs. 40.6±7.8, p<0.0001) was significantly improved. Group I showed no change of absolute infarction size (17.3±10.9 g vs. 17.5±10.4 g, p=0.8) but significant increase in relative infarction size (21.0±13.7% vs. 26.5 ±19.4%, p=0.01) because of reduction of myocardial mass after revascularization. Significant increase in regional transmural extent (35.2±22.8% vs. 39.6±24.2%, p<0.0001) and thickness of enhanced tissue (4.2±1.5 mm vs. 5.9±1.8 mm, p<0.0001) were found in group I. However, thicknesses of nonenhanced rim and remote myocardium were not changed. There were no significant changes in all variables in group II.

Late Cardiac Remodeling After Primary Percutaneous Coronary Intervention

Primary percutaneous coronary intervention (PPCI) preserves function and improves survival. The late effects of PPCI on left ventricular remodeling, however, have not yet been investigated on cardiac magnetic resonance imaging (CMRI). Twenty-five patients with acute myocardial infarction (AMI) treated with PPCI underwent CMRI within 10 days, at 4 months and at 5 years. Left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume were quantified on cine images. Infarct mass and transmural extent of infarction were quantified on contrast-enhanced imaging. In all patients EDV increased significantly in the early phase (192 ± 40 ml to 211 ± 49 ml, P ≤ 0.01) and LVEF improved significantly (42 ± 9% to 46 ± 9%, P=0.02). In the late phase (>4 months) no significant changes were observed (LVEF 44 ± 9%, P=0.07; EDV 216 ± 68 ml, P=0.38). Three different groups could be identified. One-third (32%) had no dilatation at all; one-third (32%) had limited dilatation at 4 months without progression later; and 36% had progressive dilatation both at 4 months and at late follow-up. This third group had an average increase in EDV of 20% in the acute phase followed by an additional 13%. The strongest predictor for progressive dilatation was infarct mass. Even in the era of PPCI for AMI followed by optimal medical therapy, one-third of patients had progressive dilatation, which was best predicted by infarct mass.