Late Gadolinium Enhancement Cardiovascular Magnetic Resonance Imaging Research Articles

Deep learning for automatic volumetric segmentation of left ventricular myocardium and ischaemic scar from multi-slice late gadolinium enhancement cardiovascular magnetic resonance.

This study details application of deep learning for automatic volumetric segmentation of left ventricular (LV) myocardium and scar and automated quantification of myocardial ischaemic scar burden from late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR). We included 501 images and manual segmentations of short-axis LGE-CMR from over 20 multinational sites, from which 377 studies were used for training and 124 studies from unique participants for internal validation. A third test set of 52 images was used for external evaluation. Three models, U-Net, Cascaded U-Net, and U-Net++, were trained with a novel adaptive weighted categorical cross-entropy loss function. Model performance was evaluated using concordance correlation coefficients (CCCs) for LV mass and per cent myocardial scar burden. Cascaded U-Net was found to be the best model for the quantification of LV mass and scar percentage. The model exhibited a mean difference of -5 ± 23 g for LV mass, -0.4 ± 11.2 g for scar mass, and -0.8 ± 7% for per cent scar. CCC were 0.87, 0.77, and 0.78 for LV mass, scar mass, and per cent scar burden, respectively, in the internal validation set and 0.75, 0.71, and 0.69, respectively, in the external test set. For segmental scar mass, CCC was 0.74 for apical scar, 0.91 for mid-ventricular scar, and 0.73 for basal scar, demonstrating moderate to strong agreement. We successfully trained a convolutional neural network for volumetric segmentation and analysis of LV scar burden from LGE-CMR images in a large, multinational cohort of participants with ischaemic scar.

Unsupervised unpaired multiple fusion adaptation aided with self-attention generative adversarial network for scar tissues segmentation framework

Late gadolinium enhancement (LGE) is a specialized imaging technique used in cardiovascular magnetic resonance (CMR) imaging to detect and characterize areas of scar tissue or fibrosis within the heart muscle. After a heart attack, the affected region of the heart muscle becomes scarred due to insufficient blood supply. LGE CMR enhances the infarcted myocardium to appear with distinctive brightness compared to healthy tissues. It is primarily used to assess various heart conditions and can identify the extent and location of scar tissue, helping in risk stratification and guiding treatment decisions. Automated myocardium segmentation in LGE CMR poses challenges due to intensity heterogeneity caused by the accumulation of contrast agents in infarcted areas. Furthermore, LGE CMR images with gold standard labels are particularly scarce compared to other sequences, making the task even more demanding. Besides, the heart’s motion involves complex non-rigid deformations, including regional wall thickening, circumferential, and longitudinal ventricular shortening, making it challenging to model. This work presents an unsupervised unpaired domain adaptive scar tissue segmentation framework aided with the self-attention generative adversarial network. Besides, we proposed a novel segmentation architecture based on a parallel transformer for scar segmentation and compared the results with and without style transfer GAN and unpaired style self-supervised attention GAN. Besides, to model longitudinal changes in scare, we used eight days’ time points as a source and 1 month and 12 as a target and applied our proposed attention-generative network to transfer style from one-time point to another time. Experiments on four different LGE MICCAI datasets from 2019 to 2023 achieved significantly better performance than state-of-the-art segmentation methods.

Fibrosis entropy is associated with life-threatening arrhythmia in non-ischaemic cardiomyopathy

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): This work was supported by the National Institute for Health Research Biomedical Research Centre at Guy’s and St. Thomas’ Trust and King’s College, the Centre of Excellence in Medical Engineering funded by the Wellcome Trust and Engineering and Physical Sciences Research Council (EPSRC; WT088641/Z/09/Z). M.J.B. is supported by a Medical Research Council New Investigator Grant (MR/N011007/1) and British Heart Foundation (Project grant PG/18/74/34077). This work was supported by EPSRC 2018/19 DTP - EP/R513064/1 grant. This work was supported by a National Heart and Lung Institute Foundation grant awarded to Professor Sanjay Prasad and Dr Richard Jones. Background Enhanced risk stratification for implanted defibrillator requirement represents an important area of research in patients with non-ischemic cardiomyopathy (NICM). Myocardial fibrosis represents the major underlying arrhythmic substrate in this population, and its identification on late-gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) is associated with life-threatening arrhythmia (LTA). Fibrosis entropy, a measure of scar texture heterogeneity, may confer important information regarding the underlying pro-arrhythmic mechanisms of both core scar and areas of intermediate signal intensity (Gray Zone [GZ]). Purpose We sought to: 1) evaluate whether LGE-CMR assessment of left ventricular (LV) tissue entropy had incremental utility to fibrosis presence for arrhythmic risk stratification of patients with NICM; 2) quantify the added utility of GZ entropy in such analysis. Methods This study involved a prospective observational cohort of consecutive patients with NICM and myocardial fibrosis detected on LGE-CMR. Epicardial and endocardial contours obtained from LGE-CMR data were used with a FWHM method to delineate core fibrosis (≥50% maximum signal intensity) and GZ fibrosis (≥35%-<50% signal intensity). Fibrotic masks were subsequently used, along with native dicom LGE-CMR images to compute tissue entropy, defined by the standard Shannon Entropy for core fibrosis, GZ fibrosis, and combined core+GZ fibrosis. Patients underwent adjudicated long-term follow-up for LTA (composite of sudden cardiac death, aborted sudden cardiac death or sustained ventricular tachycardia). Results Of 291 patients with NICM and mid-wall/subepicardial fibrosis, 38 patients (13.1%) experienced LTA over median follow-up of 6.3 years (interquartile range 4.6-9.1 years). On Cox regression analysis, core fibrosis entropy (Hazard ratio [HR] 1.77, 95% CI 1.25-2.54, p=0.001), GZ fibrosis entropy (HR 1.74, 95% CI 1.20-2.54, p=0.004) and combined fibrosis entropy (HR 1.98, 95% CI 1.30-2.52, p=0.001) were associated LTA after adjustment for variables used to guide ICD implantation (LVEF <35% and NYHA class >1) and remained associated in multivariable models accounting separately for core and GZ fibrosis mass. The addition of core fibrosis entropy, GZ fibrosis entropy and combined fibrosis entropy to a baseline clinical model improved the C-statistic from 0.49 to 0.59, 0.62 and 0.62, respectively. LVEF <35% was not associated with LTA (HR 1.45, 95% CI 0.77-2.74, p=0.25) on multivariable analysis. Conclusions Fibrosis entropy on LGE-CMR offers incremental utility to LVEF and fibrosis presence for arrhythmic risk prediction in patients with NICM. The combination of core and GZ fibrosis entropy offers the highest association with risk.

Head-to-Head Comparison of T1 Mapping and Electroanatomical Voltage Mapping in Patients With Ventricular Arrhythmias

BackgroundElectroanatomical voltage mapping (EAVM) has been compared with late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR), which cannot delineate diffuse fibrosis. T1-mapping CMR overcomes the limitations of LGE-CMR, but it has not been directly compared against EAVM. ObjectivesThis study aims to assess the relationship between left ventricular (LV) endocardial voltage obtained by EAVM and extracellular volume (ECV) obtained by T1 mapping. MethodsThe study investigated patients who underwent endocardial EAVM for ventricular arrhythmias (CARTO 3, Biosense Webster) together with preprocedural contrast-enhanced T1 mapping (Ingenia 3T, Philips Healthcare). After image integration, EAVM datapoints were projected onto LGE-CMR and ECV-encoded images. Average values of unipolar voltage (UV), bipolar voltage (BV), LGE transmurality, and ECV were merged from corresponding cardiac segments (6 per slice) and pooled for analysis. ResultsThe analysis included data from 628 segments from 18 patients (57 ± 13 years of age, 17% females, LV ejection fraction 48% ± 14%, nonischemic/ischemic cardiomyopathy/controls: 8/6/4 patients). Based on the 95th and 5th percentile values obtained from the controls, ECV >33%, BV <2.9 mV, and UV <6.7 mV were considered abnormal. There was a significant inverse association between voltage and ECV, but only in segments with abnormal ECV. Increased ECV could predict abnormal BV and UV with acceptable accuracy (area under the curve of 0.78 [95% CI: 0.74-0.83] and 0.84 [95% CI: 0.79-0.88]). ConclusionsThis study found a significant inverse relationship between LV endocardial voltage and ECV. Real-time integration of T1 mapping may guide catheter mapping and may allow identification of areas of diffuse fibrosis potentially related to ventricular arrhythmias.

Quantification of late gadolinium enhancement cardiovascular MRI in patients with coronary artery chronic total occlusion

To determine the most accurate and reproducible semi-automated greyscale thresholding technique for quantifying late gadolinium enhancement (LGE) in cardiovascular magnetic resonance imaging (CMRI), by using positron-emission tomography (PET) as the reference standard in patients with coronary artery chronic total occlusion (CTO). LGE in CMRI, single-photon-emission computed tomography (SPECT), and PET were performed within 1 week in each of 63 patients with known CTO. The presence and quantity of LGE were determined with greyscale thresholds of 2, 4, 5, 6, and 8 standard deviations (SDs) above the mean signal intensity for normal remote myocardium and full width at half maximum (FWHM). The infarcted myocardium was delineated by PET. Sixty-three patients and 1,008 segments were analysed. Based on patient analysis, with PET as the reference standard, the 5 SD method yielded the strongest correlation (r=0.85, p<0.0001) compared with the 2 SDs (r=0.42), 4 SDs (r=0.73), 6 SDs (r=0.81), 8 SDs (r=0.71), and FWHM (r=0.69; p<0.001 for all comparisons). The 5 SDs threshold quantification showed high interobserver and intra-observer agreement (intraclass correlation coefficient [ICC]=0.90, p<0.0001; ICC=0.93, p<0.0001, respectively). Semi-automated LGE CMRI greyscale thresholding with 5 SDs above the mean signal intensity for normal remote myocardium yields the strongest correlation to the extent of LGE identified using PET and is highly reproducible in patients with CTO.

Unrecognized myocardial infarction assessed by cardiac magnetic resonance imaging is associated with adverse long-term prognosis.

BackgroundUnrecognized myocardial infarctions (UMIs) are common. The study is an extension of a previous study, aiming to investigate the long-term (>5 year) prognostic implication of late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) detected UMI in patients with suspected stable coronary artery disease (CAD) without previously diagnosed myocardial infarction (MI).MethodsIn 235 patients with suspected stable CAD without previous MI, LGE-CMR imaging and coronary angiography were performed. LGE with a subendocardial component detectable in more than one imaging plane was required to indicate UMI. The stenosis grade of the coronary arteries was determined, including in the artery supplying an infarcted area. Stenosis ≥70% stenosis was considered significant. Patients were followed for 5.4 years in mean regarding a composite endpoint of cardiovascular death, MI, hospitalization due to heart failure, stable or unstable angina.ResultsUMI were present in 58 of 235 patients (25%). Thirty-nine of the UMIs were located downstream of a significant coronary stenosis. During the follow-up 40 patients (17.0%) reached the composite endpoint. Of patients with UMI, 34.5% (20/58) reached the primary endpoint compared to 11.3% (20/177) of patients with no UMI (HR 3.7, 95% CI 2.0–6.9, p<0.001). The association between UMI and outcome remained (HR 2.3, 95% CI 1.2–4.4, p = 0.012) after adjustments for age, gender, extent of CAD and all other variables univariate associated with outcome. Sixteen (41%) of the patients with an UMI downstream of a significant stenosis reached the endpoint compared to four (21%) patients with UMI and no relation to a significant stenosis (HR 2.4, 95% CI 0.8–7.2, p = 0.12).ConclusionThe presence of UMI was independently associated with an increased risk of cardiovascular events during long-term follow up.

Empirical Mode Decomposition and Monogenic Signal-Based Approach for Quantification of Myocardial Infarction From MR Images.

Quantification of myocardial infarction on late Gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) images into heterogeneous infarct periphery (or gray zone) and infarct core plays an important role in cardiac diagnosis, especially in identifying patients at high risk of cardiovascular mortality. However, quantification task is challenging due to noise corrupted in cardiac MR images, the contrast variation, and limited resolution of images. In this study, we propose a novel approach for automatic myocardial infarction quantification, termed DEMPOT, which consists of three key parts: Decomposition of image into intrinsic modes, monogenic phase performing on combined dominant modes, and multilevel Otsu thresholding on the phase. In particular, inspired by the Hilbert-Huang transform, we perform the multidimensional ensemble empirical mode decomposition and 2-D generalization of the Hilbert transform known as the Riesz transform on the MR image to obtain the monogenic phase that is robust to noise and contrast variation. Then, a two-stage algorithm using multilevel Otsu thresholding is accomplished on the monogenic phase to automatically quantify the myocardium into healthy, gray zone, and infarct core regions. Experiments on LGE-CMR images with myocardial infarction from 82 patients show the superior performance of the proposed approach in terms of reproducibility, robustness, and effectiveness.

Feasibility of detecting myocardial infarction in the sheep fetus using late gadolinium enhancement CMR imaging

BackgroundLate gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging has enabled the accurate assessment of myocardial infarction (MI). However, LGE CMR has not been performed successfully in the fetus, where it could be useful for animal studies of interventions to promote cardiac regeneration. We believe that LGE imaging could allow us to document the presence, extent and effect of MI in utero and would thereby expand our capacity for conducting fetal sheep MI research. We therefore aimed to investigate the feasibility of using LGE to detect MI in sheep fetuses.MethodsSix sheep fetuses underwent a thoracotomy and ligation of a left anterior descending (LAD) coronary artery branch; while two fetuses underwent a sham surgery. LGE CMR was performed in a subset of fetuses immediately after the surgery and three days later. Early gadolinium enhancement (EGE) CMR was also performed in a subset of fetuses on both days. Cine imaging of the heart was performed to measure ventricular function.ResultsThe imaging performed immediately after LAD ligation revealed no evidence of infarct on LGE (n=3). Two of four infarcted fetuses (50%) showed hypoenhancement at the infarct site on the EGE images. Three days after the ligation, LGE images revealed a clear, hyper-enhanced infarct zone in four of the five infarcted fetuses (80%). No hyper-enhanced infarct zone was seen on the one sham fetus that underwent LGE CMR. No hypoenhancement could be seen in the EGE images in either the sham (n=1) or the infarcted fetus (n=1). No regional wall motion abnormalities were apparent in two of the five infarcted fetuses.ConclusionLGE CMR detected the MI three days after LAD ligation, but not immediately after. Using available methods, EGE imaging was less useful for detecting deficits in perfusion. Our study provides evidence for the ability of a non-invasive tool to monitor the progression of cardiac repair and damage in fetuses with MI. However, further investigation into the optimal timing of LGE and EGE scans and improvement of the sequences should be pursued with the aim of expanding our capacity to monitor cardiac regeneration after MI in fetal sheep.

Baseline cardiac magnetic resonance imaging versus baseline endomyocardial biopsy for the prediction of left ventricular reverse remodeling and prognosis in response to therapy in patients with idiopathic dilated cardiomyopathy

Endomyocardial biopsy (EMB) and late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) imaging performed at baseline are both used to evaluate the extent of myocardial fibrosis. However, no study has directly compared the effectiveness of these diagnostic tools in the prediction of left ventricular reverse remodeling (LVRR) and prognosis in response to therapy in patients with idiopathic dilated cardiomyopathy (IDCM). Seventy-five patients with newly diagnosed IDCM who were undergoing optimal therapy were assessed at baseline using LGE-CMR imaging and EMB; the former measured LGE area and the latter measured collagen volume fraction (CVF) as possible predictive indices of LVRR and cardiac event-free survival. Among all the baseline primary candidate factors with P < 0.2 as per univariate analysis, multivariate analysis indicated that only LGE area was an independent predictor of subsequent LVRR (β = 0.44; 95 % confidence interval (CI) 0.87–2.53; P < 0.001), as indicated by decreasing left ventricular end-systolic volume index over the 1-year follow-up. Kaplan–Meier curves indicated significantly lower cardiac event-free survival rates in patients with LGE at baseline than in patients without (P < 0.01). By contrast, there was no significant difference in prognosis between patients with CVF values above (severe fibrosis) and below (mild fibrosis) the median of 4.9 %. Cox proportional hazard analysis showed that LGE area was an independent predictor of subsequent cardiac events (hazard ratio 1.06; 95 % CI 1.02–1.10; P ≤ 0.01). The degree of myocardial fibrosis estimated by baseline LGE-CMR imaging, but not that estimated by baseline EMB, can predict LVRR and cardiac event-free survival in response to therapy in patients with newly diagnosed IDCM.

Right ventricular function in dilated cardiomyopathy: relation to location of focal myocardial fibrosis

Background Severe right ventricular dysfunction (RVD) is an important prognostic parameter in dilated cardiomyopathy (DCM). The relationship between myocardial fibrosis of the left ventricle (LV) and particularly the septum and right ventricular (RV) function remains poorly understood. We sought to investigate this relationship in a large cohort of DCM patients using cardiovascular magnetic resonance (CMR). Methods We studied 257 patients (52±15ys,193men) with known DCM using a clinical 1.5 T CMR scanner (Philips Achieva). Short axis slices covering entirely both ventricles were acquired using standard SSFP-sequences for measurement of LV and RV volumes and ejection fraction (EF). Focal myocardial fibrosis was assessed in late gadolinium enhancement (LGE) CMR images acquired 10 minutes after i.v. injection of 0.2mmol/kg Gd-DTPA (Magnevist). SSFP and LGE CMR images were assessed by different observers who were blinded to measurement results and clinical data. Severe RVD was defined as RVEF<35%. In a subgroup of patients (n=96) invasive measurement of pulmonary artery pressure was performed. Results Mean LVEF was 35±14% while mean RVEF was 42 ±13%. Focal myocardial fibrosis was present in 92 (36%) patients and was located a) intra-murally within the inter-ventricular septum in 29 patients (LGE -septum) or b) sub-epicardially/diffuse in 63 patients (any-LGE). None of the patients had sub-endocardial LGE. LGEseptum patients exhibited a significantly higher RVEF (49±12%; vs. 40±14%;p=0.006), a higher RV EDV index (115±43 ml/m2; vs. 99±23 ml/m2 ;p=0.05) and a higher RV ESV index (73±45 ml/m2; vs. 52±22 ml/m2 ;p=0.01)

Prevalence of cardiac morphological and functional alterations in systemic lupus erythematosus patients with a low disease activity

Background Cardiac involvement in systemic lupus erythematosus (SLE) is a common complication and is associated with a considerable morbidity and mortality in these patients. As affected individuals often present with subclinical or nonspecific symptoms the betimes confirmation of cardiac manifestations is challenging. Cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE) is the current gold-standard for non-invasive tissue characterization as well as for the evaluation of systolic and diastolic function. In this study we assessed the cardiac morphology and function in SLE patients with low disease activity. Methods We studied twenty-nine SLE patients (3 male, 26 female) fulfilling the SLE diagnostic criteria of the American College of Rheumatology and compared them to thirty agematched healthy volunteers. All patients were in a stable clinical condition and only patients with a low disease activity (SLEDAI Index < 5) were included. All of them received an individually optimized medication. CMR images were acquired on a 1.5 T whole-body MRI (Achieva, Philips Healthcare, Best, The Netherlands) using a 32-element cardiac phased-array coil. Short and long axis views were obtained applying a standard clinical steady-state free-precession sequence and LGE CMR imaging was performed (Gadolinium-DTPA 0.2 mmol/kg body weight, Magnevist, Schering, Berlin, Germany) in 27 patients. Left and right ventricular (LV, RV) end-diastolic and end-systolic volumes (EDV, ESV), stroke volume (SV), ejection fraction (EF) as well as the mitral/tricuspid annular plane systolic excursion (M/TAPSE) and LV wall mass were measured. Results

Detection of papillary muscle infarction by late gadolinium enhancement: incremental value of short-inversion time vs. standard imaging

Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging can detect myocardial scar in patients with myocardial infarction. The detection of papillary muscle infarction (PMI) may be difficult due to the bright blood signal. The aim of our study was to evaluate the incremental value of LGE CMR imaging using an inversion recovery (IR)-GRE with a short-inversion time (TI) over standard LGE imaging in identifying PMI. Fifty-six patients with myocardial infarction were studied using a standard IR-GRE LGE sequence with an adjusted TI to null the signal intensity of normal myocardium and with a 3D IR-GRE with a short TI (<180 ms). Signal-to-noise and contrast-to-noise ratios (CNR) and the frequency of PMI were determined. Image quality and infarction sharpness were evaluated. The short-TI LGE sequence detected a higher number of PMI compared with standard LGE sequence (19/54 vs. 15/54) with an increased sharpness of PMI (84.2 vs. 53.3%). The CNR was higher between infarcted myocardium and blood (77.9 ± 60 vs. 19.3 ± 16, P < 0.001) and between PMI and blood (69.4 ± 51 vs. 39.4 ± 26, respectively, P = 0.0157). Our data indicate that in patients with myocardial infarction, LGE CMR imaging using a short TI may be more sensitive than standard LGE imaging for the detection of PMI.

127 Timing of cardiovascular MRI after acute myocardial infarction: effect on estimates of infarct characteristics and prediction of late ventricular remodelling

<h3>Background</h3> The pathophysiological remodelling processes associated with acute myocardial infarction (AMI) evolve over time and the optimal acute imaging time point to predict medium-term surrogates for outcome has not been established. This study aimed to define the evolution of infarct characteristics by cardiovascular magnetic resonance (CMR), and to assess whether CMR data acquired at “day 2” or at “1 week” post-AMI are stronger predictors of infarct size and left ventricular (LV) function measured at 3 months. <h3>Methods</h3> Fifty-seven patients were recruited with first presentation ST elevation AMI treated successfully with primary percutaneous coronary intervention. Cine, T2- weighted and late gadolinium enhancement CMR imaging were performed at days 2, 7, 30 and 90 after index presentation. <h3>Results</h3> Infarct size and extent of myocardial oedema decreased significantly between “day 2” and “1 week” (mean %LV-scar (SD) 27.2 (13.9) vs 21.6 (14.1), p&lt;0.001 and %LV-AAR (Area At Risk) (SD), 37.9 (15.2) vs 32.3 (14.3), p=0.003). These changes were accompanied by a significant improvement in LV ejection fraction (%LVEF (SD), 41.7 (9.6) vs 44.6 (10.1), p&lt;0.001). CMR data acquired at “1 week” were better predictors of LVEF and infarct size at “3 months” than data collected at “day 2”. <h3>Conclusions</h3> The extent of myocardial oedema and infarct size decrease significantly during the first week after reperfusion for AMI and these changes are associated with a significant improvement in LVEF over the same interval. These findings have implications for the timing of CMR studies in the early post-infarct period. We found that the percentage myocardial salvage index did not change significantly between “day 2” and “1 week”. Therefore, accurate assessment of the efficacy of reperfusion therapy can be made up to one week after revascularization. In addition, CMR data acquired at “1 week” were better predictors of CMR endpoints measured at “3 months”. Thus, we conclude that the optimal time point to image patients post-reperfusion therapy for AMI is at 1 week.

Evaluation of Papillary Muscle Function Using Cardiovascular Magnetic Resonance Imaging in Mitral Valve Prolapse

Abnormal traction and excursion of the papillary muscle (PM) can be observed in patients with mitral valve prolapse (MVP) and can adversely affect the electrophysiologic stability of the underlying myocardium. Cardiovascular magnetic resonance (CMR) techniques can directly measure the excursion and velocity of PM tips during ventricular systole. In addition, high-resolution late gadolinium enhancement (LGE) CMR imaging allows for visualization of the underlying potentially arrhythmogenic PM fibrosis substrate. We prospectively studied 16 patients with MVP and 9 healthy adult subjects using phase-contrast CMR and cine CMR to assess the PM velocity and excursion. LGE CMR was performed in 13 patients with MVP (81%). The peak PM systolic velocity and maximum PM excursion were significantly increased in those with MVP (12 +/- 5 vs 5 +/- 2 cm/s and 15 +/- 5 vs 2 +/- 3 mm, both p <0.001). Definite PM LGE was found in 6 patients (46%) but the finding did not correlate with PM velocity or excursion. In conclusion, functional CMR imaging demonstrated increased peak PM systolic velocity and excursion distance in patients with MVP. These parameters, however, did not relate to underlying PM fibrosis.

Visual estimation of the extent of myocardial hyperenhancement on late gadolinium-enhanced CMR in patients with hypertrophic cardiomyopathy

So far different approaches have been used to quantify late gadolinium enhancement (LGE) in patients with hypertrophic cardiomyopathy (HCM), but there is no general consensus on the gold standard, since histological data are scarce. The aim of our study was to investigate whether the determination of LGE in patients with HCM using a semiquantitative score based on the 17-segment model is feasible and has comparable accuracy to manual planimetry. Forty-two patients with HCM underwent LGE cardiovascular magnetic resonance imaging. Determination of LGE by planimetry based on visual assessment was used as reference standard. Then the extent of LGE was assessed using a semiquantitative score based on the standard left ventricular 17-segment model. Each segment was scored for the distribution of LGE. The resulting summed score expressed as percentage of the maximum possible score was thereafter compared with the manual planimetric evaluation of LGE, expressed as a percentage of the left ventricular myocardial area. In 28 patients (66%), LGE was present. There was a good correlation between the semiquantitative score and the planimetric approach (r=0.89; y=0.819x+2.45; standard error of estimation=2.327; P<.0001). Additionally, the Bland-Altmann plot showed a high concordance between the two approaches (mean of the difference +1.7%). The inter- and intraobserver limits of agreement and the coefficients of repeatability based on measurements with the semiquantitative score of the extent of LGE were superior to planimetric measurements. Besides, the time requirement for the LGE determination using the semiquantitative score was found to be significantly reduced compared to manual planimetry (median 2 vs. 10 min). Thus, a reliable global index of the size of the LGE is feasible and can easily be obtained from visual assessment with a semiquantitative score of the extent of the hyperenhancement.

Abstract 2751: Correlation of Left Atrial Voltage Maps with Cardiovascular MR Provides Evidence of Pre-existent Scar in Atrial Fibrillation Patients

Introduction: There is increasing evidence for and interest in detecting electrically silent left atrial (LA) myocardium which may be the substrate of atrial fibrillation (AF). Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) might detect these areas of pre-existent scar as high signal in the LA wall. We sought to correlate the extent low-voltage areas in AF patients with clinical parameters of LA volume and type of AF, and to correlate areas of low voltage with areas of high signal on LGE CMR, indicating areas of scarred tissue. Methods: Twenty-two patients with AF underwent high resolution atrial LGE CMR on a 1.5 T CMR scanner and bipolar voltage electroanatomic mapping (Carto, Biosense Webster). The number of the LA mapping points with low (&lt; 0.1mV) voltage was calculated for each patient. LA systolic volume was measured, indexed to BSA. Using the voltage maps, blood-LA contrast to noise ratio (CNR) was measured on the LGE CMR images in two areas, low and high voltage areas (N=10). Hypothesis testing used t-tests and p&lt;0.05. Results: The average extent of LA low voltage was 8 % of the LA. Four (18%) patients had no low voltage regions. The extent of low voltage for patients with non-paroxysmal vs. paroxysmal AF was 11 ± 13% vs. 4 % ± 5 % (p=0.08). The extent of low voltage for patients with larger than median LA volumes vs. smaller LA volumes was 12 ± 13% vs. 1 ± 1 % (p=0.027). In 10 patients in which LGE was measured in low and high voltage regions, the CNR was 10 vs. 6 (p=0.016). Conclusions: Patients with extensive low voltage regions in the LA have larger LA volumes. The CNR is higher in low-voltage regions, suggesting that such regions of possible scar can be identified by LGE CMR. This research has received full or partial funding support from the American Heart Association, AHA National Center.

Left atrial function and scar after catheter ablation of atrial fibrillation

Catheter ablation of atrial fibrillation (AF) involves extensive radiofrequency ablation (RFA) of the left atrium (LA) around the pulmonary veins. The effect of this therapy on LA function is not fully characterized. The purpose of this study was to determine whether catheter ablation of AF is associated with a change in LA function. LA and right atrial (RA) systolic function was assessed in 33 consecutive patients with paroxysmal or persistent AF referred for ablation using cardiovascular magnetic resonance (CMR) imaging. Steady-state free precession ECG cine CMR imaging was performed before and after (mean 48 days) AF ablation. All patients underwent circumferential pulmonary vein isolation using an 8-mm tip RFA catheter. High spatial resolution late gadolinium enhancement CMR images of LA scar were obtained in 16 patients. Maximum LA volume decreased by 15% (P <.001), and LA ejection fraction decreased by 14% (P <.001) after AF ablation. Maximum RA volume decreased by 13% (P = .018), but RA ejection fraction increased by 5% (P = .008). Mean LA scar volume was 8.1 +/- 3.7 mL. A linear correlation was observed between change in LA ejection fraction and scar volume (r = -0.75, P <.001). Catheter ablation of AF is associated with decreased LA size and reduced atrial systolic function. This change strongly correlates with the volume of LA scar. This finding may have implications for postprocedural thromboembolic risk and for procedures involving more extensive RFA.