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Assadi H, Sawh N, Bailey C, Matthews G, Li R, Grafton-Clarke C, Mehmood Z, Kasmai B, Swoboda PP, Swift AJ, van der Geest RJ, Garg P. Validation of Left Atrial Volume Correction for Single Plane Method on Four-Chamber Cine Cardiac MRI. Tomography 2024; 10:459-470. [PMID: 38668393 PMCID: PMC11054972 DOI: 10.3390/tomography10040035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 03/21/2024] [Accepted: 03/22/2024] [Indexed: 04/29/2024] Open
Abstract
BACKGROUND Left atrial (LA) assessment is an important marker of adverse cardiovascular outcomes. Cardiovascular magnetic resonance (CMR) accurately quantifies LA volume and function based on biplane long-axis imaging. We aimed to validate single-plane-derived LA indices against the biplane method to simplify the post-processing of cine CMR. METHODS In this study, 100 patients from Leeds Teaching Hospitals were used as the derivation cohort. Bias correction for the single plane method was applied and subsequently validated in 79 subjects. RESULTS There were significant differences between the biplane and single plane mean LA maximum and minimum volumes and LA ejection fraction (EF) (all p < 0.01). After correcting for biases in the validation cohort, significant correlations in all LA indices were observed (0.89 to 0.98). The area under the curve (AUC) for the single plane to predict biplane cutoffs of LA maximum volume ≥ 112 mL was 0.97, LA minimum volume ≥ 44 mL was 0.99, LA stroke volume (SV) ≤ 21 mL was 1, and LA EF ≤ 46% was 1, (all p < 0.001). CONCLUSIONS LA volumetric and functional assessment by the single plane method has a systematic bias compared to the biplane method. After bias correction, single plane LA volume and function are comparable to the biplane method.
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Affiliation(s)
- Hosamadin Assadi
- Department of Cardiovascular and Metabolic Health, Norwich Medical School, University of East Anglia, Norwich NR4 7TJ, UK
- Department of Cardiology, Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich NR4 7UY, UK
| | - Nicholas Sawh
- Faculty of Medicine, Medical University of Sofia, Blvd Akademik Ivan Evstratiev Geshov 15, 1431 Sofia, Bulgaria
| | - Ciara Bailey
- Department of Cardiovascular and Metabolic Health, Norwich Medical School, University of East Anglia, Norwich NR4 7TJ, UK
- Department of Cardiology, Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich NR4 7UY, UK
| | - Gareth Matthews
- Department of Cardiovascular and Metabolic Health, Norwich Medical School, University of East Anglia, Norwich NR4 7TJ, UK
- Department of Cardiology, Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich NR4 7UY, UK
| | - Rui Li
- Department of Cardiovascular and Metabolic Health, Norwich Medical School, University of East Anglia, Norwich NR4 7TJ, UK
- Department of Cardiology, Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich NR4 7UY, UK
| | - Ciaran Grafton-Clarke
- Department of Cardiovascular and Metabolic Health, Norwich Medical School, University of East Anglia, Norwich NR4 7TJ, UK
- Department of Cardiology, Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich NR4 7UY, UK
| | - Zia Mehmood
- Department of Cardiovascular and Metabolic Health, Norwich Medical School, University of East Anglia, Norwich NR4 7TJ, UK
- Department of Cardiology, Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich NR4 7UY, UK
| | - Bahman Kasmai
- Department of Cardiovascular and Metabolic Health, Norwich Medical School, University of East Anglia, Norwich NR4 7TJ, UK
- Department of Cardiology, Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich NR4 7UY, UK
| | - Peter P. Swoboda
- Division of Biomedical Imaging, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK
| | - Andrew J. Swift
- Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield S10 2RX, UK
| | - Rob J. van der Geest
- Department of Radiology, Division of Image Processing, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Pankaj Garg
- Department of Cardiovascular and Metabolic Health, Norwich Medical School, University of East Anglia, Norwich NR4 7TJ, UK
- Department of Cardiology, Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich NR4 7UY, UK
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2
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Zhang Y, Li XM, Shen MT, Huang S, Li Y, Yang ZG. Atrioventricular coupling and left atrial abnormality in type 2 diabetes mellitus with functional mitral regurgitation patients verified by cardiac magnetic resonance imaging. Cardiovasc Diabetol 2022; 21:100. [PMID: 35681217 PMCID: PMC9185866 DOI: 10.1186/s12933-022-01536-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 05/30/2022] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Functional mitral regurgitation (FMR) in type 2 diabetes mellitus (T2DM) patients induced by left ventricular (LV) enlargement and mitral valve abnormality may aggravated the impairment in left atrial (LA) compliance. Thus, this study aimed to depict how FMR and LV dysfunction affect LA compliance in T2DM patients with FMR. MATERIALS AND METHODS A total of 148 patients with T2DM and 49 age- and sex-matched normal controls underwent cardiac magnetic resonance examination. LA longitudinal strain and LA and LV functional indices were compared among controls and different T2DM patients. The multivariate analysis was used to identify the independent indicators of LA longitudinal strain. RESULTS T2DM Patients without FMR had a lower total LA empty fraction (LAEF) compared with the controls (all P < 0.05). T2DM patients with mild and moderate FMR showed increased LA volume (LAV) and LV volume while decreased LAEF, LA strain, and LV ejection fraction (P < 0.05). T2DM patients with severe FMR showed markedly increased LAV and LV volume while decreased LAEF, LA strain, and LVEF (P < 0.05). In T2DM patients with FMR, reservoir strain (εs) was independently correlated with LV end-diastolic volume (LVEDV) (β = - 0.334) and regurgitation degree (β = - 0.256). The passive strain (εe) was independently correlated with regurgitation degree (β = - 0.297), whereas the active strain (εa) was independently correlated with LVESV (β = - 0.352) and glycated haemoglobin (β = - 0.279). CONCLUSION FMR may aggravate LA and LV dysfunction in T2DM patients. Regurgitation degree was an independent determinant of the εs and the εe, LVEDV was an independent determinant of the εs, and LVESV was an independent determinant of the εa in T2DM patients with FMR.
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Affiliation(s)
- Yi Zhang
- Department of Radiology, West China Hospital, Sichuan University, 37# Guo Xue Xiang, Chengdu, 610041, Sichuan, China.,Department of Radiology, School of Medicine, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, University of Electronic Science and Technology of China, 55# Lan 4 RenMing Road (South), Chengdu, 610041, Sichuan, China
| | - Xue-Ming Li
- Department of Radiology, West China Hospital, Sichuan University, 37# Guo Xue Xiang, Chengdu, 610041, Sichuan, China.,Department of Radiology, School of Medicine, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, University of Electronic Science and Technology of China, 55# Lan 4 RenMing Road (South), Chengdu, 610041, Sichuan, China
| | - Meng-Ting Shen
- Department of Radiology, West China Hospital, Sichuan University, 37# Guo Xue Xiang, Chengdu, 610041, Sichuan, China
| | - Shan Huang
- Department of Radiology, West China Hospital, Sichuan University, 37# Guo Xue Xiang, Chengdu, 610041, Sichuan, China
| | - Yuan Li
- Department of Radiology, West China Hospital, Sichuan University, 37# Guo Xue Xiang, Chengdu, 610041, Sichuan, China
| | - Zhi-Gang Yang
- Department of Radiology, West China Hospital, Sichuan University, 37# Guo Xue Xiang, Chengdu, 610041, Sichuan, China.
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Benjamin MM, Moulki N, Waqar A, Ravipati H, Schoenecker N, Wilber D, Kinno M, Rabbat M, Sanagala T, Syed MA. Association of left atrial strain by cardiovascular magnetic resonance with recurrence of atrial fibrillation following catheter ablation. J Cardiovasc Magn Reson 2022; 24:3. [PMID: 34980165 PMCID: PMC8722067 DOI: 10.1186/s12968-021-00831-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 11/23/2021] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Atrial fibrillation (AF) is a progressive condition, which is characterized by inflammation/fibrosis of left atrial (LA) wall, an increase in the LA size/volumes, and decrease in LA function. We sought to investigate the relationship of anatomical and functional parameters obtained by cardiovascular magnetic resonance (CMR), with AF recurrence in paroxysmal AF (pAF) patients after catheter ablation. METHODS We studied 80 consecutive pAF patients referred for ablation, between January 2014 and December 2019, who underwent pre- and post-ablation CMR while in sinus rhythm. LA volumes were measured using the area-length method and included maximum, minimum, and pre-atrial-contraction volumes. CMR-derived LA reservoir strain (ℇR), conduit strain (ℇCD), and contractile strain (ℇCT) were measured by computer assisted manual planimetry. We used a multivariate logistical regression to estimate the independent predictors of AF recurrence after ablation. RESULTS Mean age was 58.6 ± 9.4 years, 75% men, mean CHA2DS2-VASc score was 1.7, 36% had prior cardioversion and 51% were taking antiarrhythmic drugs. Patients were followed for a median of 4 years (Q1-Q3 = 2.5-6.2 years). Of the 80 patients, 21 (26.3%) patients had AF recurrence after ablation. There were no significant differences between AF recurrence vs. no recurrence groups in age, gender, CHA2DS2-VASc score, or baseline comorbidities. At baseline, patients with AF recurrence compared to without recurrence had lower LV end systolic volume index (32 ± 7 vs 37 ± 11 mL/m2; p = 0.045) and lower ℇCT (7.1 ± 4.6 vs 9.1 ± 3.7; p = 0.05). Post-ablation, patients with AF recurrence had higher LA minimum volume (68 ± 32 vs 55 ± 23; p = 0.05), right atrial volume index (62 ± 20 vs 52 ± 19 mL/m2; p = 0.04) and lower LA active ejection fraction (24 ± 8 vs 29 ± 11; p = 0.05), LA total ejection fraction (39 ± 14 vs 46 ± 12; p = 0.02), LA expansion index (73.6 ± 37.5 vs 94.7 ± 37.1; p = 0.03) and ℇCT (6.2 ± 2.9 vs 7.3 ± 1.7; p = 0.04). Adjusting for clinical variables in the multivariate logistic regression model, post-ablation minimum LA volume (OR 1.09; CI 1.02-1.16), LA expansion index (OR 0.98; CI 0.96-0.99), and baseline ℇR (OR 0.92; CI 0.85-0.99) were independently associated with AF recurrence. CONCLUSION Significant changes in LA volumes and strain parameters occur after AF ablation. CMR derived baseline ℇR, post-ablation minimum LAV, and expansion index are independently associated with AF recurrence.
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Affiliation(s)
- Mina M Benjamin
- Division of Cardiovascular Medicine, Loyola University Medical Center, Stritch School of Medicine, Maywood, IL, USA
| | - Naeem Moulki
- Division of Cardiovascular Medicine, Loyola University Medical Center, Stritch School of Medicine, Maywood, IL, USA
| | - Aneeq Waqar
- Department of Internal Medicine, Loyola University Medical Center, Maywood, IL, USA
| | - Harish Ravipati
- Department of Internal Medicine, MacNeal Hospital, Berwyn, IL, USA
| | - Nancy Schoenecker
- Division of Cardiovascular Medicine, Loyola University Medical Center, Stritch School of Medicine, Maywood, IL, USA
| | - David Wilber
- Division of Cardiovascular Medicine, Loyola University Medical Center, Stritch School of Medicine, Maywood, IL, USA
| | - Menhel Kinno
- Division of Cardiovascular Medicine, Loyola University Medical Center, Stritch School of Medicine, Maywood, IL, USA
| | - Mark Rabbat
- Division of Cardiovascular Medicine, Loyola University Medical Center, Stritch School of Medicine, Maywood, IL, USA
| | - Thriveni Sanagala
- Division of Cardiovascular Medicine, Loyola University Medical Center, Stritch School of Medicine, Maywood, IL, USA
| | - Mushabbar A Syed
- Division of Cardiovascular Medicine, Loyola University Medical Center, Stritch School of Medicine, Maywood, IL, USA.
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Wu KC, Wongvibulsin S, Tao S, Ashikaga H, Stillabower M, Dickfeld TM, Marine JE, Weiss RG, Tomaselli GF, Zeger SL. Baseline and Dynamic Risk Predictors of Appropriate Implantable Cardioverter Defibrillator Therapy. J Am Heart Assoc 2020; 9:e017002. [PMID: 33023350 PMCID: PMC7763383 DOI: 10.1161/jaha.120.017002] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Background Current approaches fail to separate patients at high versus low risk for ventricular arrhythmias owing to overreliance on a snapshot left ventricular ejection fraction measure. We used statistical machine learning to identify important cardiac imaging and time-varying risk predictors. Methods and Results Three hundred eighty-two cardiomyopathy patients (left ventricular ejection fraction ≤35%) underwent cardiac magnetic resonance before primary prevention implantable cardioverter defibrillator insertion. The primary end point was appropriate implantable cardioverter defibrillator discharge or sudden death. Patient characteristics; serum biomarkers of inflammation, neurohormonal status, and injury; and cardiac magnetic resonance-measured left ventricle and left atrial indices and myocardial scar burden were assessed at baseline. Time-varying covariates comprised interval heart failure hospitalizations and left ventricular ejection fractions. A random forest statistical method for survival, longitudinal, and multivariable outcomes incorporating baseline and time-varying variables was compared with (1) Seattle Heart Failure model scores and (2) random forest survival and Cox regression models incorporating baseline characteristics with and without imaging variables. Age averaged 57±13 years with 28% women, 66% white, 51% ischemic, and follow-up time of 5.9±2.3 years. The primary end point (n=75) occurred at 3.3±2.4 years. Random forest statistical method for survival, longitudinal, and multivariable outcomes with baseline and time-varying predictors had the highest area under the receiver operating curve, median 0.88 (95% CI, 0.75-0.96). Top predictors comprised heart failure hospitalization, left ventricle scar, left ventricle and left atrial volumes, left atrial function, and interleukin-6 level; heart failure accounted for 67% of the variation explained by the prediction, imaging 27%, and interleukin-6 2%. Serial left ventricular ejection fraction was not a significant predictor. Conclusions Hospitalization for heart failure and baseline cardiac metrics substantially improve ventricular arrhythmic risk prediction.
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Affiliation(s)
- Katherine C Wu
- Department of Medicine Division of Cardiology Johns Hopkins University School of Medicine Baltimore MD
| | - Shannon Wongvibulsin
- Department of Biomedical Engineering and School of Medicine Johns Hopkins University Baltimore MD
| | - Susumu Tao
- Department of Medicine Division of Cardiology Johns Hopkins University School of Medicine Baltimore MD
| | - Hiroshi Ashikaga
- Department of Medicine Division of Cardiology Johns Hopkins University School of Medicine Baltimore MD.,Department of Biomedical Engineering and School of Medicine Johns Hopkins University Baltimore MD
| | | | - Timm M Dickfeld
- Department of Medicine University of Maryland Medical Systems Baltimore MD
| | - Joseph E Marine
- Department of Medicine Division of Cardiology Johns Hopkins University School of Medicine Baltimore MD
| | - Robert G Weiss
- Department of Medicine Division of Cardiology Johns Hopkins University School of Medicine Baltimore MD.,The Russell H. Morgan Department of Radiology and Radiological Science Johns Hopkins University School of Medicine Baltimore MD
| | | | - Scott L Zeger
- Department of Biostatistics Johns Hopkins Bloomberg School of Public Health Baltimore MD
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5
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Her AY, Shin ES, Zhou Q, Wierzbinski J, Vidal-Lopez S, Saleh A, Kim YH, Garg S, Jung F, Brachmann J. Magnetocardiography detects left atrial dysfunction in paroxysmal atrial fibrillation. Clin Hemorheol Microcirc 2019; 72:353-363. [PMID: 30958336 DOI: 10.3233/ch-180528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Magnetocardiography (MCG) is a non-invasive technique and to characterize the magnetic field, a pseudo-current conversion was used. The role of MCG in detecting left atrial (LA) dysfunction in patients with paroxysmal atrial fibrillation (PAF) is unknown. OBJECTIVE The aim of this study was to evaluate LA function using MCG in patients with PAF and healthy subjects, to identify possible indices to diagnose PAF. METHODS We enrolled a total of 70 subjects including 26 healthy volunteers (group 1) and 22 marathon runners (group 2) who did not exhibit any cardiac abnormalities, and 22 patients with PAF (group 3) which was documented by electrocardiography (ECG). Spatiotemporal activation graph (STAG) in base-apex and left-right direction was reconstructed. The maximum value of LA pseudo-current under rest and peak exercise were measured between the end of the P wave and beginning of the Q wave. RESULTS LA pseudo-current increase at peak exercise in PAF patients was significantly lower than in healthy volunteers and marathon runners (0.4±0.3 pT in group 3 vs. 0.8±0.3 pT in group 1 vs. 1.1±0.5 pT in group 2, p < 0.001). PAF patients had less pseudo-current increase in STAG at peak exercise than healthy volunteers and marathon runners (46% of 26 PAF patients, 81% of 22 healthy subjects vs. 81% of 22 marathon runners, p = 0.002). Sensitivity, specificity, and the area under the receiver-operator characteristics curve of LA pseudo-current increase at peak exercise for differentiating PAF patients from healthy subjects were 77%, 92%, and 0.896. CONCLUSIONS MCG can provide important non-invasive information for detecting LA dysfunction in PAF patients. Therefore, MCG may help in differentiating PAF patients from healthy subjects.
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Affiliation(s)
- Ae-Young Her
- Department of Internal Medicine, Division of Cardiology, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Eun-Seok Shin
- Division of Cardiology, Ulsan Medical Center, Ulsan Hospital, Ulsan, South Korea
| | - Qing Zhou
- Department of Medical II., Coburg Hospital, Coburg, Germany
| | - Jan Wierzbinski
- Department of Cardiology, Asklepios Hospital Harburg, Hamburg, Germany
| | | | - Ahmed Saleh
- Department of Medical II., Coburg Hospital, Coburg, Germany
| | - Yong Hoon Kim
- Department of Internal Medicine, Division of Cardiology, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Scot Garg
- East Lancashire Hospitals NHS Trust, Blackburn, Lancashire, UK
| | - Friedrich Jung
- Institute for Clinical Hemostasiology and Transfusion Medicine, University of Saarland, Saarbrücken, Germany
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6
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Leng S, Tan RS, Zhao X, Allen JC, Koh AS, Zhong L. Validation of a rapid semi-automated method to assess left atrial longitudinal phasic strains on cine cardiovascular magnetic resonance imaging. J Cardiovasc Magn Reson 2018; 20:71. [PMID: 30396356 PMCID: PMC6219067 DOI: 10.1186/s12968-018-0496-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 10/09/2018] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Abnormal left atrial (LA) function is a marker of cardiac dysfunction and adverse cardiovascular outcome, but is difficult to assess, and hence not, routinely quantified. We aimed to determine the feasibility and effectiveness of a fast method to measure long-axis LA strain and strain rate (SR) with standard cardiovascular magnetic resonance (CMR) compared to conventional feature tracking (FT) derived longitudinal strain. METHODS We studied 50 normal controls, 30 patients with hypertrophic cardiomyopathy, and 100 heart failure (HF) patients, including 40 with reduced ejection fraction (HFrEF), 30 mid-range ejection fraction (HFmrEF) and 30 preserved ejection fraction (HFpEF). LA longitudinal strain and SR parameters were derived by tracking the distance between the left atrioventricular junction and a user-defined point at the mid posterior LA wall on standard cine CMR two- and four-chamber views. LA performance was analyzed at three distinct cardiac phases: reservoir function (reservoir strain εs and strain rate SRs), conduit function (conduit strain εe and strain rate SRe) and booster pump function (booster strain εa and strain rate SRa). RESULTS There was good agreement between LA longitudinal strain and SR assessed using the fast and conventional FT-CMR approaches (r = 0.89 to 0.99, p < 0.001). The fast strain and SRs showed a better intra- and inter-observer reproducibility and a 55% reduction in evaluation time (85 ± 10 vs. 190 ± 12 s, p < 0.001) compared to FT-CMR. Fast LA measurements in normal controls were 35.3 ± 5.2% for εs, 18.1 ± 4.3% for εe, 17.2 ± 3.5% for εa, and 1.8 ± 0.4, - 2.0 ± 0.5, - 2.3 ± 0.6 s- 1 for the respective phasic SRs. Significantly reduced LA strains and SRs were observed in all patient groups compared to normal controls. Patients with HFpEF and HFmrEF had significantly smaller εs, SRs, εe and SRe than hypertrophic cardiomyopathy, and HFmrEF had significantly impaired LA reservoir and booster function compared to HFpEF. The fast LA strains and SRs were similar to FT-CMR for discriminating patients from controls (area under the curve (AUC) = 0.79 to 0.96 vs. 0.76 to 0.93, p = NS). CONCLUSIONS Novel quantitative LA strain and SR derived from conventional cine CMR images are fast assessable parameters for LA phasic function analysis.
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Affiliation(s)
- Shuang Leng
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, Singapore, 169609 Singapore
| | - Ru-San Tan
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, Singapore, 169609 Singapore
- Duke-NUS Medical School, 8 College Road, Singapore, 169857 Singapore
| | - Xiaodan Zhao
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, Singapore, 169609 Singapore
| | - John C. Allen
- Duke-NUS Medical School, 8 College Road, Singapore, 169857 Singapore
| | - Angela S. Koh
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, Singapore, 169609 Singapore
- Duke-NUS Medical School, 8 College Road, Singapore, 169857 Singapore
| | - Liang Zhong
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, Singapore, 169609 Singapore
- Duke-NUS Medical School, 8 College Road, Singapore, 169857 Singapore
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