Novel Cardiac Magnetic Resonance Feature Tracking (CMR-FT) Analysis for Detection of Myocardial Fibrosis in Pediatric Hypertrophic Cardiomyopathy

The role of diagnostic modalities in differentiating hypertensive heart disease and hypertrophic cardiomyopathy: strategies in adults for potential application in paediatrics

Hypertensive heart disease and hypertrophic cardiomyopathy both lead to left ventricular hypertrophy despite differing in aetiology. Elucidating the correct aetiology of the presenting hypertrophy can be a challenge for clinicians, especially in patients with overlapping risk factors. Furthermore, drugs typically used to combat hypertensive heart disease may be contraindicated for the treatment of hypertrophic cardiomyopathy, making the correct diagnosis imperative. In this review, we discuss characteristics of both hypertensive heart disease and hypertrophic cardiomyopathy that may enable clinicians to discriminate the two as causes of left ventricular hypertrophy. We summarise the current literature, which is primarily focused on adult populations, containing discriminative techniques available via diagnostic modalities such as electrocardiography, echocardiography, and cardiac MRI, noting strategies yet to be applied in paediatric populations. Finally, we review pharmacotherapy strategies for each disease with regard to pathophysiology.

Prevalence and clinical significance of late gadolinium enhancement in children and adolescents with hypertrophic cardiomyopathy: a systematic review and meta-analysis

OBJECTIVES

Hypertrophic cardiomyopathy is the leading cause of sudden cardiac death among the paediatric population. The aim of this study is to investigate the prevalence and clinical significance of late gadolinium enhancement, as assessed by cardiac MRI, in paediatric hypertrophic cardiomyopathy.

METHODS

A systematic literature search was conducted in PubMed, SCOPUS, and Ovid SP to identify relevant studies. Pooled estimates with a 95% confidence interval were calculated using the random-effects generic inverse variance model. Statistical analysis was performed using Review Manager v5.4 and R programming.

RESULTS

Seventeen studies were included in this meta-analysis, encompassing a total of 778 patients. Late gadolinium enhancement was highly prevalent in paediatric hypertrophic cardiomyopathy, with a pooled prevalence of 51% (95% confidence interval, 40-62%). The estimated extent of focal fibrosis expressed as a percentage of left ventricular mass was 4.70% (95% confidence interval, 2.11-7.30%). The presence of late gadolinium enhancement was associated with an increased risk of adverse cardiac events (pooled odds ratio 3.49, 95% confidence interval 1.10-11.09). The left ventricular mass index of late gadolinium enhancement-positive group was higher than the negative group, with a standardised mean difference of 0.91 (95% confidence interval, 0.42-1.41).

CONCLUSION

This meta-analysis demonstrates that prevalence of late gadolinium enhancement in paediatric hypertrophic cardiomyopathy is similar to that in the adult population. The presence and extent of late gadolinium enhancement are independent predictors of adverse cardiac events, underscoring their prognostic significance among the paediatric population.

Wall motion assessment by feature tracking in pediatric patients with coronary anomalies undergoing dobutamine stress CMR

Background

Left ventricular (LV) wall motion assessment is an important adjunct in addition to perfusion defects in assessing ischemic changes. This study aims to investigate the feasibility and utility of performing feature tracking (FT) in pediatric patients with coronary anomalies undergoing dobutamine stress CMR to assess wall motion abnormalities (WMA) and perfusion defects.

Method

This is a retrospective study where 10 patients with an inducible first-pass perfusion (FPP) defect and 10 without were selected. Global LV circumferential strain/strain rate (GCS/GCSR) was measured at rest and at peak stress (systole and diastole) using a commercially available feature tracking software. Peak GCS and GCSR were compared to indexed wall motion score (WMSI) between groups with and without FPP defect and in subjects with and without WMA.

Results

The median age of patients was 13.5 years (Q1, 11 years; Q3, 15 years). Five subjects had qualitatively WMA at peak stress. A moderate correlation of GCS with WMSI at peak stress (0.48, p = 0.026) and a significant difference between GCS at rest and stress in patients with no inducible WMA (p = 0.007) were seen. No significant difference was noted in GCS between rest and stress in patients with WMA (p = 0.13). There was a larger absolute GCS/GCSR at peak stress in subjects with no inducible FPP defect or WMA.

Conclusion

Smaller absolute GCS and a lack of significant change in GCS at peak stress in those with inducible WMA or perfusion defect are suggestive of compromised LV deformation in subjects with inducible WMA. Given these findings, GCS derived from CMR-FT may be used to objectively assess WMA in pediatric patients undergoing stress CMR.

Comparison of manual and artificial intelligence based quantification of myocardial strain by feature tracking-a cardiovascular MR study in health and disease

OBJECTIVES

The analysis of myocardial deformation using feature tracking in cardiovascular MR allows for the assessment of global and segmental strain values. The aim of this study was to compare strain values derived from artificial intelligence (AI)-based contours with manually derived strain values in healthy volunteers and patients with cardiac pathologies.

MATERIALS AND METHODS

A cohort of 136 subjects (60 healthy volunteers and 76 patients; of those including 46 cases with left ventricular hypertrophy (LVH) of varying etiology and 30 cases with chronic myocardial infarction) was analyzed. Comparisons were based on quantitative strain analysis and on a geometric level by the Dice similarity coefficient (DSC) of the segmentations. Strain quantification was performed in 3 long-axis slices and short-axis (SAX) stack with epi- and endocardial contours in end-diastole. AI contours were checked for plausibility and potential errors in the tracking algorithm.

RESULTS

AI-derived strain values overestimated radial strain (+ 1.8 ± 1.7% (mean difference ± standard deviation); p = 0.03) and underestimated circumferential (- 0.8 ± 0.8%; p = 0.02) and longitudinal strain (- 0.1 ± 0.8%; p = 0.54). Pairwise group comparisons revealed no significant differences for global strain. The DSC showed good agreement for healthy volunteers (85.3 ± 10.3% for SAX) and patients (80.8 ± 9.6% for SAX). In 27 cases (27/76; 35.5%), a tracking error was found, predominantly (24/27; 88.9%) in the LVH group and 22 of those (22/27; 81.5%) at the insertion of the papillary muscle in lateral segments.

CONCLUSIONS

Strain analysis based on AI-segmented images shows good results in healthy volunteers and in most of the patient groups. Hypertrophied ventricles remain a challenge for contouring and feature tracking.

CLINICAL RELEVANCE STATEMENT

AI-based segmentations can help to streamline and standardize strain analysis by feature tracking.

KEY POINTS

• Assessment of strain in cardiovascular magnetic resonance by feature tracking can generate global and segmental strain values. • Commercially available artificial intelligence algorithms provide segmentation for strain analysis comparable to manual segmentation. • Hypertrophied ventricles are challenging in regards of strain analysis by feature tracking.

[The association between cardiac mr feature tracking strain and myocardial late gadolinium enhancement in patients with hypertrophic cardiomyopathy]

Aim    Hypertrophic cardiomyopathy (HCM) is a relatively common, heritable cardiomyopathy, and cardiac magnetic resonance (CMR) studies have been performed previously to evaluate different aspects of the disease. However, a comprehensive study, including all four cardiac chambers and analysis of left atrial (LA) function, is missing in the literature. The aim of this retrospective study was to analyze CMR-feature tracking (CMR-FT) strain parameters and atrial function of HCM patients and to investigate the association of these parameters with the amount of myocardial late gadolinium enhancement (LGE).Material and Methods    In this retrospective, cross-sectional study, we analyzed the CMR images (CMRI) of 58 consecutive patients, who from February 2020 to September 2022 were diagnosed with HCM at our tertiary cardiovascular center. Patients who were younger than 18 yrs or who had moderate or severe valvular heart disease, significant coronary artery disease, previous myocardial infarction, suboptimal image quality, or with contraindication to CMR were excluded. CMRI was performed at 1.5 T with a scanner, and all scans were assessed by an experienced cardiologist and then re-assessed by an experienced radiologist. SSFP 2-, 3- and 4‑chamber, short axis views were obtained and left ventricular (LV) end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), and mass were measured. LGE images were obtained using a PSIR sequence. Native T1 and T2 mapping and post-contrast T1 map sequences were performed and each patient's myocardial extracellular volume (ECV) was calculated. LA volume index (LAVI), LA ejection fraction (LAEF), LA coupling index (LACI) were calculated. The complete CMR analysis of each patient was performed with CVI 42 software (Circle CVi, Calgary, Canada), off-line.Results    The patients were divided into two groups, HCM with LGE (n=37, 64 %) and HCM without LGE (n=21, 36 %). The average patient age in the HCM patients with LGE was 50.8±14 yrs and 47±12.9 yrs in the HCM patients without LGE. Maximum LV wall thickness and basal antero-septum thickness were significantly higher in the HCM with LGE group compared to the HCM without LGE group (14.8±3.5 mm vs 20.3±6.5 mm (p<0.001), 14.2±3.2 mm vs 17.3±6.1 mm (p=0.015), respectively). LGE was 21.9±31.7 g and 15.7±13.4 % in the HCM with LGE group. LA area (22.2±6.1 vs 28.8±11.2 cm2; p=0.015) and LAVI (28.9±10.2 vs 45.6±23.1; p-0.004) were significantly higher in the HCM with LGE group. LACI was doubled in the HCM with LGE group (0.2±0.1 vs 0.4±0.2; p<0.001). LA strain (30.4±13.2 vs 21.3±16.2; p-0.04) and LV strain (15.2±3 vs 12.2±4.5; p=0.012) were significantly decreased in the HCM with LGE group.Conclusion    This study sheds light on the CMR-FT differences between HCM with and without LGE. We found a greater burden of LA volume but significantly lower LA and LV strain in the LGE patients. These findings highlight further the LA and LV remodeling in HCM. Impaired LA function appears to have physiological significance, being associated with greater LGE. While our CMR-FT findings support the progressive nature of HCM, beginning with sarcomere dysfunction to eventual fibrosis, further studies are needed to validate these results in larger cohorts and to evaluate their clinical relevance.

Cardiac MRI in Fabry disease

Fabry disease is a rare, progressive X-linked inherited disorder of glycosphingolipid metabolism due to a deficiency of α-galactosidase A enzyme. It leads to the accumulation of globotriaosylceramide within lysosomes of multiple organs, predominantly the vascular, renal, cardiac, and nervous systems. Fabry cardiomyopathy is characterized by increased left ventricular wall thickness/mass, functional abnormalities, valvular heart disease, arrhythmias, and heart failure. Early diagnosis and treatment are critical to avoid cardiac or renal complications that can significantly reduce life expectancy in untreated FD. This review will focus on the role of cardiovascular magnetic resonance imaging in the diagnosis, clinical decision-making, and monitoring of treatment efficacy.

Detecting Regional Fibrosis in Hypertrophic Cardiomyopathy: The Utility of Myocardial Strain Based on Cardiac Magnetic Resonance

RATIONALE AND OBJECTIVES

The value of myocardial strain for reflecting fibrosis in patients with hypertrophic cardiomyopathy (HCM) on cardiac magnetic resonance (CMR) has not been definite. We aim to explore whether there are underlying non-contrast parameters to evaluate myocardial fibrosis and screen which may be the best.

MATERIALS AND METHODS

We retrospectively included 127 HCM patients (89 men; average age 46.6 ± 15.6 years) and 30 healthy controls (20 men; average age 52.0 ± 13.2 years) who have undergone late gadolinium enhancement (LGE) CMR. Next, 127 HCM patients were divided randomly into two sets including training cohort and validation cohort. Strain and imaging parameters were measured and analyzed statistically.

RESULTS

Based on univariate and multivariate analysis, segmental circumferential strain (SCS) (p < 0.001) and maximal wall thickness (MWT) (p < 0.001) may differentiate myocardial segments with or without LGE as significant biomarkers for both sets. The area under the curve (AUC) was 0.803 (95% CI 0.785-0.820) for SCS and 0.777 (95% CI 0.759-0.795) for MWT to identify myocardial fibrosis. When combining SCS >-13.9% and MWT >16.4mm, the specificity of the model (AUC = 0.779; 95% CI 0.760-0.796) achieved the highest 93.9%, with a sensitivity of 61.8%.

CONCLUSION

Strain analysis in HCM holds promise for myocardial fibrosis detection and SCS is the best strain parameter based on CMR. Nevertheless, the model of combining SCS and MWT could achieve the highest specificity for fibrotic diagnosis.

Clinical Utility of Strain Imaging in Assessment of Myocardial Fibrosis

Myocardial fibrosis (MF) is a non-reversible process that occurs following acute or chronic myocardial damage. MF worsens myocardial deformation, remodels the heart and raises myocardial stiffness, and is a crucial pathological manifestation in patients with end-stage cardiovascular diseases and closely related to cardiac adverse events. Therefore, early quantitative analysis of MF plays an important role in risk stratification, clinical decision, and improvement in prognosis. With the advent and development of strain imaging modalities in recent years, MF may be detected early in cardiovascular diseases. This review summarizes the clinical usefulness of strain imaging techniques in the non-invasive assessment of MF.

Predictive value of cardiac magnetic resonance mechanical parameters for myocardial fibrosis in hypertrophic cardiomyopathy with preserved left ventricular ejection fraction

Objective

Myocardial fibrosis leads to systolic dysfunction in hypertrophic cardiomyopathy (HCM) patients. This study aims to investigate the relationship between cardiac magnetic resonance mechanical parameters for evaluating the left ventricular function in HCM with preserved left ventricular ejection fraction (LVEF ≥50%) and the association between myocardial fibrosis defined by late gadolinium enhancement (LGE).

Methods

This study was a retrospective analysis of CMR images of 93 patients with HCM with preserved ejection fraction (HCMpEF) and 96 controls diagnosed by cardiac magnetic resonance (CMR) at our hospital from July 2019 to January 2022. The myocardial contraction fraction (MCF) was calculated, and myocardial mechanical parameters, including global myocardial longitudinal strain (GLS), circumferential strain (GLS), and myocardial strain (GLS), were obtained by tissue tracking and LGE quantitative modules of dedicated software, respectively. The correlation between myocardial strain and LGE was analyzed, and a multivariate logistic regression model was developed to discuss the risk predictors of LGE.

Results

Compared to the control group, the left ventricular mechanical parameters GLS (-13.90 ± 3.80% versus -18.20 ± 2.10%, p < 0.001), GCS (-16.62 ± 3.50% versus -18.4 ± 2.69%, p < 0.001), GRS (28.99 ± 10.38% versus 33.02 ± 6.25%, p < 0.01), and MCF (64 ± 16% versus 99 ± 18%, p < 0.001) were found significantly lower in HCM group. Moreover, even in LGE-negative HCM patients, GLS (-16.3 ± 3.9%) and MCF (78 ± 19%) were significantly lower compared to the control group. Left ventricular GLS [OR = 1.61, (1.29, 2.02), p = 0.001] and MCF [OR = 0.90, (0.86, 0.94), p = 0.001] independently predicted myocardial late gadolinium enhancement (LGE).

Conclusion

In participants of HCM with preserved ejection fraction, the early onset of reduced left ventricular GLS and MCF in patients with HCMpEF may provide new evidence for evaluating impaired myocardial systolic function. The reduction of myocardial mechanical indexes may reflect the presence and extent of myocardial fibrosis, and the more significant the reduction, the more severe the myocardial fibrosis; GLS and MCF may be ideal predictors for LGE.

CMR feature tracking in patients with dilated cardiomyopathy: patterns of myocardial strain and focal fibrosis

BACKGROUND

There is a paucity of data on cardiovascular magnetic resonance feature tracking (CMR-FT) in patients with dilated cardiomyopathy (DCM). We aimed at describing global and segmental myocardial strain patterns and a potential association with the presence of focal myocardial scarring in DCM patients by CMR-FT.

METHODS

Thirty-nine patients with DCM and reduced left ventricular (LV) ejection fraction (mean 21±8%) underwent CMR including standard cine steady-state free precession (SSFP) sequences and late gadolinium enhancement (LGE). We measured global LV longitudinal as well as global and segmental circumferential and radial strain. The presence of focal myocardial fibrosis was assessed on LGE images.

RESULTS

Nineteen patients had focal myocardial fibrosis on LGE images with the highest prevalence in the basal septal segments II and III, which were affected in 12 (63%) and 13 (68%) patients. Furthermore, there was a significantly lower average short-axis LV radial strain (LV_SAX-RS) in these segments (4.89 (-1.55 to 11.34) %) compared with the average of the other myocardial segments (21.20 (17.36 to 25.05)%; p<0.001) after adjusting for LGE and left-bundle branch block (LBBB). In general, LV segments with LGE had lower model-based mean LV_SAX-RS values (17.65 (10.37 to 24.93) %) compared with those without LGE (19.40 (15.43 to 23.37) %), but this effect was not significant after adjusting for the presence of LBBB (p=0.630).

CONCLUSION

Our findings revealed a coincidence of impaired radial strain and focal myocardial fibrosis in the basal septal LV myocardial segments of patients with DCM. Regardless of this pattern, we did not find a general, significant effect of myocardial fibrosis on strain in our cohort. Future studies are required to assess the potential prognostic implications of myocardial strain patterns in addition to the assessment of myocardial fibrosis in patients with DCM.

Association of Whole-Heart Myocardial Mechanics by Transthoracic Echocardiography with Presence of Late Gadolinium Enhancement by CMR in Non-Ischemic Dilated Cardiomyopathy

Background: In patients with non-ischemic dilated cardiomyopathy (NIDCM), myocardial fibrosis (MF) is related to adverse cardiovascular outcomes. The purpose of this study was to evaluate the potential relationship between the myocardial mechanics of different chambers of the heart and the presence of MF and to determine the accuracy of the whole-heart myocardial strain parameters to predict MF in patients with NIDCM. Methods: We studied 101 patients (64% male; 50 ± 11 years) with a first-time diagnosis of NIDCM who were referred for a clinical cardiovascular magnetic resonance (CMR) and speckle tracking 2D echocardiography examination. We analyzed MF by late gadolinium enhancement (LGE), and the whole-heart myocardial mechanics were assessed by speckle tracking. The presence of MF was related to worse strain parameters in both ventricles and atria. The strongest correlations were found between MF and left ventricle (LV) global longitudinal strain (GLS) (r = −0.586, p < 0.001), global circumferential strain (GCS) (r = −0.609, p < 0.001), LV ejection fraction (LVEF) (r = 0.662, p < 0.001), and left atrial strain during the reservoir phase (LASr) (r = 0.588, p < 0.001). However, the binary logistic regression analysis revealed that only LV GLS, GCS, and LASr were independently associated with the presence of MF (area under the curves of 0.84, 0.85, and 0.64, respectively). None of the echocardiographic parameters correlated with fibrosis localization. Conclusions: In NIDCM patients, MF is correlated with reduced mechanical parameters in both ventricles and atria. LV GLS, LASr, and LV GCS are the most accurate 2D echocardiography predictive factors for the presence of MF.

Cardiac Magnetic Resonance at 3.0 T in Patients With C282Y Homozygous Hereditary Hemochromatosis: Superiority of Radial and Circumferential Strain Over Cardiac T2* Measurements at Baseline and at Post Venesection Follow-up

BACKGROUND

Iron-overload cardiomyopathy initially manifests with diastolic dysfunction and can progress to dilated cardiomyopathy if untreated. Previous studies have shown that patients with primary and secondary hemochromatosis can have subclinical left ventricle dysfunction with abnormalities on strain imaging. This study aimed to evaluate the relationship between cardiac T2* values and myocardial-wall strain in patients with hereditary hemochromatosis (HH) at the time of diagnosis and after a course of venesection treatment.

MATERIALS AND METHODS

Baseline cardiac magnetic resonance (CMR) at 3 T was performed in 19 patients with newly diagnosed HH with elevated serum ferritin levels and repeated after a course of treatment with venesection. Quantitative T2* mapping and strain analysis were performed offline using dedicated relaxometry fitting and feature-tracking software.

RESULTS

The majority (84%) of patients had normal baseline myocardial T2* values (mean 19.3 ms, range 8.9 to 31.2 ms), which improved significantly after venesection (mean 24.1 ms, range 11 to 38.1 ms) ( P =0.021). Mean global radial strain significantly improved from 25.0 (range: 15.6 to 32.9) to 28.3 (range: 19.8 to 35.8) ( P =0.001) and mean global circumferential strain improved, decreasing from -15.7 (range: -11.1 to -19.2) to -17.1 (range: -13.0 to -20.1) ( P =0.001).

CONCLUSION

Patients with HH may have normal T2* values in the presence of subclinical left ventricle dysfunction, which can be detected by abnormal radial and circumferential strain. As strain imaging improves following venesection in HH, it may serve as a useful biomarker to guide treatment.

SCMR expert consensus statement for cardiovascular magnetic resonance of acquired and non-structural pediatric heart disease

Cardiovascular magnetic resonance (CMR) is widely used for diagnostic imaging in the pediatric population. In addition to structural congenital heart disease (CHD), for which published guidelines are available, CMR is also performed for non-structural pediatric heart disease, for which guidelines are not available. This article provides guidelines for the performance and reporting of CMR in the pediatric population for non-structural ("non-congenital") heart disease, including cardiomyopathies, myocarditis, Kawasaki disease and systemic vasculitides, cardiac tumors, pericardial disease, pulmonary hypertension, heart transplant, and aortopathies. Given important differences in disease pathophysiology and clinical manifestations as well as unique technical challenges related to body size, heart rate, and sedation needs, these guidelines focus on optimization of the CMR examination in infants and children compared to adults. Disease states are discussed, including the goals of CMR examination, disease-specific protocols, and limitations and pitfalls, as well as newer techniques that remain under development.

Usefulness of Tissue Tracking by Cardiac Magnetic Resonance to Predict Events in Patients With Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HC) is the most common cardiovascular inherited disease, and it is associated with arrhythmic events, heart failure, and death. Strain analysis by tissue tracking (TT) techniques on cardiac magnetic resonance (CMR) is a novel noninvasive diagnostic tool. However, the usefulness of CMR-TT to identify patients with HC at risk of adverse outcomes remains unknown. CMR strain parameters by CMR-TT were prospectively measured in a cohort of 136 consecutive patients with HC. Clinical (death or readmission for heart failure) and arrhythmic (any ventricular tachycardia) events during follow-up were prospectively recorded. Global radial systolic strain rate and global radial diastolic strain rate showed the best area under the receiver operating characteristic curve (ROC curve) to predict adverse clinical events. On Cox multivariate regression models, a global radial systolic strain rate value <1.4/s and a global radial diastolic strain rate value ≥ -1.38/s were independently associated with clinical events at follow-up (adjusted hazard ratio 6.57, 95% confidence interval [CI] 2.01 to 21.49, p = 0.002; adjusted hazard ratio 5.96, 95% CI 1.79 to 19.89, p = 0.004, respectively). Regarding arrhythmic events, global radial peak strain <27% showed the best area under the ROC curve and remained independently associated with ventricular tachycardia after adjustment for confounders (odds ratio 7.33, 95% CI 1.07 to 50.41, p = 0.043). CMR strain parameters by TT predict clinical and arrhythmic events in patients with HC.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the use of cardiovascular magnetic resonance in pediatric congenital and acquired heart disease : Endorsed by The American Heart Association

Cardiovascular magnetic resonance (CMR) has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of CMR in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of CMR in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the Use of Cardiac Magnetic Resonance in Pediatric Congenital and Acquired Heart Disease: Endorsed by The American Heart Association

Cardiovascular magnetic resonance has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of cardiovascular magnetic resonance in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of cardiovascular magnetic resonance in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Echocardiographic and Cardiac Magnetic Resonance Imaging-Derived Strains in Relation to Late Gadolinium Enhancement in Hypertrophic Cardiomyopathy

We compared speckle tracking echocardiography (STE) and feature tracking cardiovascular magnetic resonance (FT-CMR) in patients with hypertrophic cardiomyopathy (HC) with a varying extent of fibrosis as defined by late gadolinium enhancement to look at the level of agreement between methods and their ability to relate those to myocardial fibrosis. At 2 reference centers, 79 patients with HC and 16 volunteers (the control group) underwent STE and CMR with late gadolinium enhancement and FT-CMR. Patients were classified into 3 categories: no detectable, limited, and extensive fibrosis. Global longitudinal strain (GLS) and global radial strain (GRS) were derived using FT-CMR and STE. STE-derived GRS was decreased in all HC categories compared with the control group (p <0.001), whereas FT-CMR GRS was reduced only in patients with HC with fibrosis (p <0.05). Reduced STE-derived GLS was associated with extensive fibrosis (p <0.05) and a value less than -15.2% identified those with extensive fibrosis (sensitivity 79%, specificity 92%, area under the curve 0.863, 95% confidence interval [CI] 0.76 to 0.97, p <0.001). Inter-modality agreement was moderate for STE versus CMR-GLS (overall population intra-class correlation coefficient = 0.615, 95% CI 0.42 to 0.75, p <0.001; patients with HC 0.63, 0.42 to 0.76, p <0.001) and GRS (overall population intra-class correlation coefficient = 0.601, 95% CI 0.397 to 0.735, p <0.001). A low level of agreement for GRS was seen between methods in patients with HC. In conclusion, strain indexes measured using echocardiography and CMR are reduced in patients with HC compared with the control group and correlate well with the burden of myocardial fibrosis. Reduced STE-GLS can identify patients with extensive fibrosis, but whether there is an added value for risk stratification for sudden cardiac death remains to be determined.

Association between left ventricular strain and cardiac iron load in beta-thalassaemia major: a cardiac magnetic resonance study

OBJECTIVE

To evaluate the utility of cardiac magnetic resonance feature tracking-derived left ventricular strain in assessing cardiac dysfunction and investigate the correlation between left ventricular strain and myocardial T2* in patients with beta-thalassaemia major.

METHODS

Forty-two patients with beta-thalassaemia major, having a mean age of 22.49 ± 8.48 years, and age-matched healthy controls were enrolled in the study. The observer drew regions of interest on the interventricular septum, and T2* decay curves were calculated accordingly. The short-axis cine images were used to derive left ventricular circumferential and radial strains, and the long-axis four-chamber and two-chamber images were used to assess left ventricular longitudinal strain.

RESULTS

The mean global left ventricular strains were lower in beta-thalassaemia major patients than the controls (p < 0.05). Left ventricular strains of beta-thalassaemia major patients with cardiac T2* values of > 20 ms were also significantly reduced compared with the controls (p < 0.05); there was no difference between the mean left ventricular ejection fractions of the two groups (p = 0.84). Cardiac T2* showed a weak correlation with left ventricular ejection fraction (r = 0.33, p = 0.03), while the left ventricular circumferential strain showed a good positive correlation with cardiac T2* (r = 0.6, p < 0.0001).

CONCLUSION

Compared with healthy controls, patients with beta-thalassaemia major, including those with myocardial T2* values of >20 ms, showed reduced global left ventricular strains. Left ventricular circumferential strain was positively correlated with myocardial T2*. Left ventricular strain analysis using cardiac magnetic resonance feature tracking may have utility in beta-thalassaemia major assessment.Key FindingsPatients with beta-thalassaemia major, including those with myocardial T2* values of >20 ms, had reduced global left ventricular strains.Cardiac T2* showed a weak correlation with left ventricular ejection fraction, while the left ventricular circumferential strain showed a good positive correlation with cardiac T2*.ImportanceLeft ventricular strain using cardiac magnetic resonance feature tracking might be used as an adjunct in assessing cardiac functions in beta-thalassaemia major.

Evaluation of comprehensive myocardial contractility in children with Kawasaki disease by cardiac magnetic resonance in a large single center

BACKGROUND

Children with Kawasaki disease (KD) and coronary artery lesions (CALs) can develop myocardial ischemia, fibrosis, and abnormal contractility. We aimed to assess the association between myocardial mechanical deformation with myocardial fibrosis, ischemia, and CALs.

METHODS

In total, 76 KD and 20 healthy volunteers received cardiac magnetic resonance (CMR). Peak systolic left ventricular (LV) longitudinal, radial, and circumferential strain and strain rate [LV strain longitudinal (LVSL), LV strain radial (LVSR), LV strain circumferential (LVSC), LV strain rate longitudinal (LVSRL), LV strain rate radial (LVSRR), and LV strain rate circumferential (LVSRC)], along with late gadolinium enhancement (LGE), perfusion deficit, and CALs in related segments were analyzed. The KD group was subdivided by CALs, perfusion, and LGE results, and strain results were compared with controls and in subgroups.

RESULTS

Cardiac fibrosis and ischemia were not confined to the territory of CALs. In a global analysis, strain and strain rates were lower in the KD group, especially in the subgroup with LGE and perfusion deficit. In segmental analysis, LVSR, LVSC, LVSL, and LVSRR decreased in the giant aneurysm group, and a lower LVSR (20.369%±10.603% vs. 26.071%±12.349%) and LVSC (-13.37%±5.365% vs. -15.847%±5.778%) were observed in thrombosed segments. The strain and strain rate were all lower in segments with LGE and perfusion deficit, and no obvious difference was found between groups with and without stenosis. LVSR had a better ability to identify giant aneurysm, thrombosis, stenosis, perfusion deficit, and LGE.

CONCLUSIONS

We detected lower strain values in KD patients, which was more pronounced in segments with aneurysm, thrombi, LGE, and perfusion deficit. LVSR is useful to discern patients with higher risk.

Global Circumferential Strain by Cardiac Magnetic Resonance Tissue Tracking Associated With Ventricular Arrhythmias in Hypertrophic Cardiomyopathy Patients

Background: Hypertrophic cardiomyopathy (HCM) is prone to myocardial heterogeneity and fibrosis, which are the substrates of ventricular arrhythmias (VAs). Cardiac magnetic resonance tissue tracking (CMR-TT) can quantitatively reflect global and regional left ventricular strain from different directions. It is uncertain whether the change of myocardial strain detected by CMR-TT is associated with VAs. The aim of the study is to explore the differential diagnostic value of VAs in HCM by CMR-TT.

Materials and Methods: We retrospectively included 93 HCM patients (38 with VAs and 55 without VAs) and 30 healthy cases. Left ventricular function, myocardial strain parameters and percentage of late gadolinium enhancement (%LGE) were evaluated.

Results: Global circumferential strain (GCS) and %LGE correlated moderately (r = 0.51, P < 0.001). HCM patients with VAs had lower left ventricular ejection fraction (LVEF), global radial strain (GRS), GCS, and global longitudinal strain (GLS), but increased %LGE compared with those without VAs (P < 0.01 for all). %LGE and GCS were indicators of VAs in HCM patients by multivariate logistic regression analysis. HCM patients with %LGE >5.35% (AUC 0.81, 95% CI 0.70–0.91, P < 0.001) or GCS >-14.73% (AUC 0.79, 95% CI 0.70–0.89, P < 0.001) on CMR more frequently had VAs. %LGE + GCS were able to better identify HCM patients with VAs (AUC 0.87, 95% CI 0.79–0.95, P < 0.001).

Conclusion: GCS and %LGE were independent risk indicators of VAs in HCM. GCS is expected to be a good potential predictor in identifying HCM patients with VAs, which may provide important values to improve risk stratification in HCM in clinical practice.

Efficacy of Novel Noncontrast Cardiac Magnetic Resonance Methods in Indicating Fibrosis in Hypertrophic Cardiomyopathy

OBJECTIVE

In hypertrophic cardiomyopathy (HCM), myocardial fibrosis is routinely shown by late gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR) imaging. We evaluated the efficacy of 2 novel contrast-free CMR methods, namely, diffusion-weighted imaging (DWI) and feature-tracking (FT) method, in detecting myocardial fibrosis.

METHODS

This cross-sectional study was conducted on 26 patients with HCM. Visual and quantitative comparisons were made between DWI and LGE images. Regional longitudinal, circumferential, and radial strains were compared between LGE-positive and LGE-negative segments. Moreover, global strains were compared between LGE-positive and LGE-negative patients as well as between patients with mild and marked LGE.

RESULTS

All 3 strains showed significant differences between LGE-positive and LGE-negative segments (P < 0.001). The regional longitudinal and circumferential strain parameters showed significant associations with LGE (P < 0.001), while regional circumferential strain was the only independent predictor of LGE in logistic regression models (OR: 1.140, 95% CI: 1.073 to 1.207, P < 0.001). A comparison of global strains between patients with LGE percentages of below 15% and above 15% demonstrated that global circumferential strain was the only parameter to show impairment in the group with marked myocardial fibrosis, with borderline significance (P=0.09). A review of 212 segments demonstrated a qualitative visual agreement between DWI and LGE in 193 segments (91%). The mean apparent diffusion coefficient was comparable between LGE-positive and LGE-negative segments (P=0.51).

CONCLUSIONS

FT-CMR, especially regional circumferential strain, can reliably show fibrosis-containing segments in HCM. Further, DWI can function as an efficient qualitative method for the estimation of the fibrosis extent in HCM.

Diagnostic value of left atrial strain in pediatric hypertrophic cardiomyopathy with normal maximum left atrial volume index: preliminary cardiac magnetic resonance study

BACKGROUND

The maximum left atrial volume index is the most widely used metric for assessing the left atrium in hypertrophic cardiomyopathy; however, it may be normal in the early phases of the disease.

OBJECTIVE

To assess whether pediatric hypertrophic cardiomyopathy patients with normal maximum left atrial volume index have impaired atrial functions on cardiac magnetic resonance imaging (MRI).

MATERIALS AND METHOD

A total of 26 pediatric hypertrophic cardiomyopathy patients and 24 age-matched children, as controls, were enrolled in the study. The left atrial reservoir, conduit and booster strain were calculated from two orthogonal planes and the left atrial volumes were calculated using the biplanar method. The extent of left ventricular late gadolinium enhancement (LGE-%) was calculated using the thresholding method. The left ventricular early diastolic longitudinal strain rate was calculated to assess diastolic dysfunction.

RESULTS

The maximum left atrial volume index of the children with hypertrophic cardiomyopathy and the controls were not significantly different (P>0.05). Most of the left atrial functional indices were worse in children with hypertrophic cardiomyopathy (P<0.05), yet no difference was observed between the left atrial booster strains of the two groups (P>0.05). The left atrial conduit strain showed moderate to good negative correlations with left ventricular LGE-% and diastolic dysfunction.

CONCLUSION

Left atrial conduit and reservoir strains are impaired in pediatric hypertrophic cardiomyopathy patients with normal maximum left atrial volumetric indices. Most left atrial strain parameters are closely linked to left ventricular LGE-% and diastolic dysfunction. Left atrial strain analysis may reveal subtle functional changes in the atrium before the increase in the maximum volume index.

Cardiac magnetic resonance image diagnosis of hypertrophic obstructive cardiomyopathy based on a double-branch neural network

OBJECTIVE

Cardiac magnetic resonance (CMR) imaging is a well-established technique for diagnosis of hypertrophic obstructive cardiomyopathy (HOCM) and evaluation of cardiac function, but the process is complicated and time consuming. Therefore, this paper proposes a cardiomyopathy recognition algorithm using a multi-task learning mechanism and a double-branch deep learning neural network.

METHOD

We implemented a double-branch neural network CMR-based HOCM recognition algorithm. Compared with the traditional classification algorithms such as the ResNet, DenseNet network, contrast the accuracy of network classification of cardiomyopathy is higher by 10.11%.

RESULT

The loss curve of the algorithm basically converges in 100 rounds, and the convergence speed of the algorithm is twice that of the traditional algorithm. The accuracy of this algorithm to classify cardiomyopathy is 96.79%, and the sensitivity is 95.24%, which is 10.11% higher than the conventional algorithm.

CONCLUSION

The CMR imaging automatic recognition algorithm for HOCM capture static morphological and motion characteristics of the heart, and comprehensively enhances recognition accuracy when the sample size is limited.

Quantification of myocardial deformation in patients with Fabry disease by cardiovascular magnetic resonance feature tracking imaging

Background

Cardiac involvement is a major contributor of morbidity and mortality in Fabry disease (FD). Early detection and accurate evaluation of the disease progression is important in management. Cardiovascular magnetic resonance (CMR) derived feature fracking (FT) is a validated quantitative method of assessing myocardial deformation which may reflect early changes of myocardial function and track disease severity. We sought to evaluate the utility of CMR-FT as a measure of myocardial dysfunction in FD.

Methods

Twenty FD patients (12 males, 40.8±14.9 years) and 20 age and sex matched healthy controls (10 males, 40.5±7.2 years) were prospectively enrolled. Subjects underwent CMR including cine, pre-/post-contrast T1 mapping and late gadolinium enhancement (LGE). FD patients were divided into three groups; group 1: patients without left ventricular hypertrophy (LVH) and LGE negative; group 2: patients with LVH positive, LGE either positive or negative; group 3: patients with LGE positive, LV wall thinning and heart failure. FT derived strain indices were measured and its associations with other processes were investigated.

Results

In FD patients, 14 (70%) had LVH and 4 (20%) had LGE. Compared with normal controls, LV global longitudinal strain (GLS) were reduced significantly in all three Fabry groups (all P<0.05), global circumferential strain (GCS) were reduced only in group 2 and group 3 (P<0.05). Among three FD groups, there were significant differences of LV GLS, GCS, native T1 value and extracellular volume fraction (ECV) (all P<0.01), group 1 had mild LV strain indices impairment, group 3 had the most severe LV strain indices. When compared between FD subgroups, GLS and GCS showed significant difference between each two groups (all P<0.05). There were weak correlations between the LV functional parameters (ejection fraction, LV mass index), maximal wall thickness, T1 mapping indices (native T1, ECV) and LV strain indices. The strongest relation was between global longitudinal early diastolic strain rate and native T1 value (r=0.783, P<0.01).

Conclusions

CMR strain imaging identifies myocardial deformation in FD in different stages. Strain imaging can track disease severity and may be an alternative method for follow-up of FD patients.

Detection of subclinical myocardial dysfunction in cocaine addicts with feature tracking cardiovascular magnetic resonance

BACKGROUND

Cocaine is an addictive, sympathomimetic drug with potentially lethal effects. We have previously shown with cardiovascular magnetic resonance (CMR) the presence of cardiovascular involvement in a significant percentage of consecutive asymptomatic cocaine addicts. CMR with feature-tracking analysis (CMR-FT) allows for the quantification of myocardial deformation which may detect preclinical involvement. Therefore, we aimed to assess the effects of cocaine on the left ventricular myocardium in a group of asymptomatic cocaine users with CMR-FT.

METHODS

In a cohort of asymptomatic cocaine addicts (CA) who had been submitted to CMR at 3 T, we used CMR-FT to measure strain, strain rate and dyssynchrony index in CA with mildly decreased left ventricular ejection fraction (CA-LVEFd) and in CA with preserved ejection fraction (CA-LVEFp). We also measured these parameters in 30 age-matched healthy subjects.

RESULTS

There were no differences according to age. Significant differences were seen in global longitudinal, radial and circumferential strain, in global longitudinal and radial strain rate and in radial and circumferential dyssynchrony index among the groups, with the lowest values in CA-LVEFd and intermediate values in CA-LVEFp. Longitudinal, radial and circumferential strain values were significantly lower in CA-LVEFp with respect to controls.

CONCLUSIONS

CA-LVEFp show decreased systolic strain and strain rate values, with intermediate values between healthy controls and CA-LVEFd. Signs suggestive of dyssynchrony were also detected. In CA, CMR-FT based strain analysis can detect early subclinical myocardial involvement.

Advanced myocardial characterization in hypertrophic cardiomyopathy: feasibility of CMR-based feature tracking strain analysis in a case-control study

OBJECTIVES

This study aimed to evaluate the feasibility and reproducibility of using cardiovascular magnetic resonance feature tracking (CMR-FT) for analysis of bi-ventricular strain and strain rate (SR) in hypertrophic cardiomyopathy (HCM) patients as well as to explore the correlation between right ventricular (RV) and left ventricular (LV) deformation.

METHODS

A total of 60 HCM patients and 48 controls were studied. Global and segmental peak values of bi-ventricular longitudinal, circumferential, radial strain, and systolic SR were analyzed. Pearson analysis was performed to investigate the correlation of RV and LV deformation. Intra-observer and inter-observer reproducibility were also assessed.

RESULTS

LV mass in the HCM group was significantly higher than that in the control group. LV end-systolic and end-diastolic volume and RV end-systolic and end-diastolic volume in the HCM group were all significantly lower than the correlated parameters in the control group (p < 0.001, respectively), whereas no statistical difference was found in ejection fraction (p > 0.05). Global longitudinal strain (GLS), global longitudinal strain rate (GLSR), global circumferential strain (GCS), global circumferential strain rate (GCSR), global radial strain (GRS), and global radial strain rate (GRSR) of the LV and RV were all significantly lower than the control group, and segmental strain and SR were also true (p < 0.001, respectively). Bi-ventricular strain and SR measurements were highly reproducible at both intra- and inter-observer levels. Additionally, Pearson analysis showed RV GCS, GLS, and GRS positively correlated with LV GCS, GLS, and GRS (r = 0.713, p < 0.001; r = 0.728, p < 0.001; r = 0.730, p < 0.001, respectively).

CONCLUSIONS

CMR-FT is a promising approach to analyze impairment of global and segmental myocardium deformation in HCM patients non-invasively and quantitatively.

KEY POINTS

• CMR-FT allows for advanced myocardial characterization with high reproducibility. • As compared with controls, HCM patients have significant differences in CMR-FT strain analysis while ejection fraction was similar. • CMR-FT may serve as an early biomarker of HCM in subjects at risk.

Cardiac Magnetic Resonance Imaging Features in Hypertrophic Cardiomyopathy Diagnosed at <21 Years of Age

Hypertrophic cardiomyopathy (HC) is the most common inherited cardiomyopathy, with varied timing of phenotypic and clinical presentation. Literature describing cardiac magnetic resonance (CMR) imaging and late gadolinium enhancement (LGE) in young patients with HC is limited. This study included patients diagnosed with HC at young age (<21 years) between January 1990 and January 2015 who underwent transthoracic echocardiography and CMR with assessment of LGE at a single tertiary referral center. LGE was quantified via a method of 6 standard deviations and patients were grouped based upon presence or absence of LGE (≤1% and >1% LGE, respectively). Sudden cardiac death (SCD) risk was assessed in patients >16 years of age using the European SCD risk score. A composite outcome of New York Heart Association class III-IV symptoms, aborted SCD, heart transplantation, and all-cause mortality was assessed via Kaplan-Meier curves with log-rank analysis. Overall, 126 patients were included (78 male; 62%). Median age of diagnosis was 15 (12 to 18) years. LGE was present in 81 (64%) patients, although only 4 (3%) patients had LGE >15%. Median age at CMR imaging was 19 (15 to 23) years. Patients with LGE had greater wall thickness (25 ± 8 mm vs 22 ± 7 mm, p = 0.01). Median European SCD risk score was 4.7 (2.9 to 6.5). Median follow-up was 6.5 (2.5 to 13) years with 26 patients (21%) meeting the composite outcome. There were no significant differences in composite outcome since age of diagnosis when stratified by presence/absence of LGE (p = 1.0). The presence of LGE in young HC patients was not an independent risk factor for cardiovascular morbidity and mortality. Wall thickness was greater in patients with LGE. There remains a need for further evaluation of this unique HC cohort.

Altered regional myocardial velocities by tissue phase mapping and feature tracking in pediatric patients with hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is associated with heart failure, atrial fibrillation and sudden death. Reduced myocardial function has been reported in HCM despite normal left ventricular (LV) ejection fraction. Additionally, LV fibrosis is associated with elevated T1 and might be an outcome predictor.

OBJECTIVE

To systematically compare tissue phase mapping and feature tracking for assessing regional LV function in children and young adults with HCM and pediatric controls, and to evaluate structure-function relationships among myocardial velocities, LV wall thickness and myocardial T1.

MATERIALS AND METHODS

Seventeen pediatric patients with HCM and 21 age-matched controls underwent cardiac MRI including standard cine imaging, tissue phase mapping (two-dimensional cine phase contrast with three-directional velocity encoding), and modified Look-Locker inversion recovery to calculate native global LV T1. Maximum LV wall thickness was measured on cine images. LV radial, circumferential and long-axis myocardial velocity time courses, as well as global and segmental systolic and diastolic peak velocities, were quantified from tissue phase mapping and feature tracking.

RESULTS

Both tissue phase mapping and feature tracking detected significantly decreased global and segmental diastolic radial and long-axis peak velocities (by 12-51%, P<0.001-0.05) in pediatric patients with HCM vs. controls. Feature tracking peak velocities were lower than directly measured tissue phase mapping velocities (mean bias = 0.3-2.9 cm/s). Diastolic global peak velocities correlated moderately with global T1 (r = -0.57 to -0.72, P<0.01) and maximum wall thickness (r = -0.37 to -0.61, P<0.05).

CONCLUSION

Both tissue phase mapping and feature tracking detected myocardial velocity changes in children and young adults with HCM vs. controls. Associations between impaired diastolic LV velocities and elevated T1 indicate structure-function relationships in HCM.

Tissue characterisation and myocardial mechanics using cardiac MRI in children with hypertrophic cardiomyopathy

INTRODUCTION

Distinguishing between hypertrophic cardiomyopathy and other causes ofleft ventricular hypertrophy can be difficult in children. We hypothesised that cardiac MRI T1 mapping could improve diagnosis of paediatric hypertrophic cardiomyopathy and that measures of myocardial function would correlate with T1 times and extracellular volume fraction.

METHODS

Thirty patients with hypertrophic cardiomyopathy completed MRI with tissue tagging, T1-mapping, and late gadolinium enhancement. Left ventricular circumferential strain was calculated from tagged images. T1, partition coefficient, and synthetic extracellular volume were measured at base, mid, apex, and thickest area of myocardial hypertrophy. MRI measures compared to cohort of 19 healthy children and young adults. Mann-Whitney U, Spearman's rho, and multivariable logistic regression were used for statistical analysis.

RESULTS

Hypertrophic cardiomyopathy patients had increased left ventricular ejection fraction and indexed mass. Hypertrophic cardiomyopathy patients had decreased global strain and increased native T1 (-14.3% interquartile range [-16.0, -12.1] versus -17.3% [-19.0, -15.7], p < 0.001 and 1015 ms [991, 1026] versus 990 ms [972, 1001], p = 0.019). Partition coefficient and synthetic extracellular volume were not increased in hypertrophic cardiomyopathy. Global native T1 correlated inversely with ejection fraction (ρ = -0.63, p = 0.002) and directly with global strain (ρ = 0.51, p = 0.019). A logistic regression model using ejection fraction and native T1 distinguished between hypertrophic cardiomyopathy and control with an area under the receiver operating characteristic curve of 0.91.

CONCLUSION

In this cohort of paediatric hypertrophic cardiomyopathy, strain was decreased and native T1 was increased compared with controls. Native T1 correlated with both ejection fraction and strain, and a model using native T1 and ejection fraction differentiated patients with and without hypertrophic cardiomyopathy.

Prevalence and Progression of Late Gadolinium Enhancement in Children and Adolescents With Hypertrophic Cardiomyopathy

BACKGROUND

Late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMR) is believed to represent dense replacement fibrosis. It is seen in ≈60% of adult patients with hypertrophic cardiomyopathy (HCM). However, the prevalence of LGE in children and adolescents with HCM is not well established. In addition, longitudinal studies describing the development and evolution of LGE in pediatric HCM are lacking. This study assesses the prevalence, progression, and clinical correlations of LGE in children and adolescents with, or genetically predisposed to, HCM.

METHODS

CMR scans from 195 patients ≤21 years of age were analyzed in an observational, retrospective study, including 155 patients with overt HCM and 40 sarcomere mutation carriers without left ventricular (LV) hypertrophy. The extent of LGE was quantified by measuring regions with signal intensity >6 SD above nulled remote myocardium.

RESULTS

Patients were 14.3±4.5 years of age at baseline and 68% were male. LGE was present in 70 (46%) patients with overt HCM (median extent, 3.3%; interquartile range, 0.8-7.1%), but absent in mutation carriers without LV hypertrophy. Thirty-one patients had >1 CMR (median interval between studies, 2.4 years; interquartile range, 1.5-3.2 years). LGE was detected in 13 patients (42%) at baseline and in 16 patients (52%) at follow-up CMR. The median extent of LGE increased by 2.4 g/y (range, 0-13.2 g/y) from 2.9% (interquartile range, 0.8-3.2%) of LV mass to 4.3% (interquartile range, 2.9-6.8%) ( P=0.02). In addition to LGE, LV mass and left atrial volume, indexed to body surface area, and z score for LV mass, as well, increased significantly from first to most recent CMR.

CONCLUSIONS

LGE was present in 46% of children and adolescents with overt HCM, in contrast to ≈60% typically reported in adult HCM. In the subset of patients with serial imaging, statistically significant increases in LGE, LV mass, and left atrial size were detected over 2.5 years, indicating disease progression over time. Further prospective studies are required to confirm these findings and to better understand the clinical implications of LGE in pediatric HCM.

Natural History of Cardiomyopathy in Adult Dogs With Golden Retriever Muscular Dystrophy

Background

Duchenne muscular dystrophy (DMD) is an X‐linked disease that causes progressive muscle weakness. Affected boys typically die from respiratory or cardiac failure. Golden retriever muscular dystrophy (GRMD) is genetically homologous with DMD and causes analogous skeletal and cardiac muscle disease. Previous studies have detailed features of GRMD cardiomyopathy in mostly young dogs. Cardiac disease is not well characterized in adult GRMD dogs, and cardiac magnetic resonance (CMR) imaging studies have not been completed.

Methods and Results

We evaluated echocardiography and CMR in 24 adult GRMD dogs at different ages. Left ventricular systolic and diastolic functions, wall thickness, and myocardial strain were assessed with echocardiography. Features evaluated with CMR included left ventricular function, chamber size, myocardial mass, and late gadolinium enhancement. Our results largely paralleled those of DMD cardiomyopathy. Ejection fraction and fractional shortening correlated well with age, with systolic dysfunction occurring at ≈30 to 45 months. Circumferential strain was more sensitive than ejection fraction in early disease detection. Evidence of left ventricular chamber dilatation provided proof of dilated cardiomyopathy. Late gadolinium enhancement imaging showed DMD‐like left ventricular lateral wall lesions and earlier involvement of the anterior septum. Multiple functional indexes were graded objectively and added, with and without late gadolinium enhancement, to give cardiac and cardiomyopathy scores of disease severity. Consistent with DMD, there was parallel skeletal muscle involvement, as tibiotarsal joint flexion torque declined in tandem with cardiac function.

Conclusions

This study established parallels of progressive cardiomyopathy between dystrophic dogs and boys, further validating GRMD as a model of DMD cardiac disease.

Clinical applications of feature-tracking cardiac magnetic resonance imaging

Cardiovascular diseases represent the leading cause of mortality and morbidity in the western world. Assessment of cardiac function is pivotal for early diagnosis of primitive myocardial disorders, identification of cardiac involvement in systemic diseases, detection of drug-related cardiac toxicity as well as risk stratification and monitor of treatment effects in patients with heart failure of various etiology. Determination of ejection fraction with different imaging modalities currently represents the gold standard for evaluation of cardiac function. However, in the last few years, cardiovascular magnetic resonance feature tracking techniques has emerged as a more accurate tool for quantitative evaluation of cardiovascular function with several parameters including strain, strain-rate, torsion and mechanical dispersion. This imaging modality allows precise quantification of ventricular and atrial mechanics by directly evaluating myocardial fiber deformation. The purpose of this article is to review the basic principles, current clinical applications and future perspectives of cardiovascular magnetic resonance myocardial feature tracking, highlighting its prognostic implications.

Prognostic implications of global myocardial mechanics in hypertrophic cardiomyopathy by cardiovascular magnetic resonance feature tracking. Relations to left ventricular hypertrophy and fibrosis

BACKGROUND

Interstitial fibrosis, myocardial fiber disarray and non-uniform shortening are common histological features of hypertrophic cardiomyopathy (HCM). The degree of LV hypertrophy and fibrosis are postulated to contribute to the impairment of myocardial shortening. Cardiovascular magnetic resonance myocardial (CMR) feature tracking (CMR-FT) has emerged as a robust method that provides quantitative measurements of myocardial deformation. Our aim was first to evaluate LV strain parameters in HCM by CMR-FT and their dependence on both functional parameters and late gadolinium enhancement (LGE); and secondly we sought to determine their association with major cardiovascular outcomes.

METHODS AND RESULTS

74 patients with HCM and 75 controls subjects underwent a CMR study including LGE imaging. Global peak longitudinal, circumferential and radial systolic strain values (GLS, GCS, GRS) were measured by CMR-FT. A primary endpoint of all-cause mortality and secondary combined endpoint of hospital admission related to heart failure, lethal ventricular arrhythmias or cardiovascular death were defined. Patients with HCM showed attenuation of all LV strain values (p<0.001). Multivariate analysis showed that both LV hypertrophy and %of LGE were independent predictors of attenuated LV strains. All systolic LV strain parameters were impaired in patients with primary and secondary endpoints (follow up time: 25.6±9.9months, p<0.05 and p<0.01 respectively). Abnormal GLS, GCS and GRS were significantly associated with primary and secondary endpoints.

CONCLUSION

Both LV hypertrophy and fibrosis contribute to the impairment of LV myocardial mechanics in HCM. In this population, reduced LV strain is associated with poor cardiac outcomes, particularly cardiovascular mortality and HF.

Biatrial performance in children with hypertrophic cardiomyopathy: CMR study

OBJECTIVES

To investigate biatrial mechanics and their relation with left ventricular outflow tract (LVOT) obstruction (LVOTO), the degree of hypertrophy, indices of ventricular diastolic function and fibrosis in children with hypertrophic cardiomyopathy (HCM).

METHODS

Fifty-five consecutive, prospectively recruited children with HCM (mean age 12.5 ± 4.6 years, 69.1% male), 19 (34.5%) of whom had LVOTO, underwent cardiac magnetic resonance and echocardiography with quantification of phasic components of biatrial function, biventricular diastolic function and fibrosis. Twenty healthy, sex-matched subjects served as controls.

RESULTS

We found a significant increase of left atrial (LA) and right atrial (RA) volumes and reduction in the majority of indices of contractile function, strains and strain rates (p < 0.05) in children with HCM compared with controls. Nearly all of the LA dynamics markers attained a significant association with the LVOT gradient (p < 0.05), the RA volumes and contractile functions were affected by LV fibrosis and mass (p < 0.05), and the RA mechanical components were related to the degree of LVOTO (p < 0.05). The minority of biatrial dynamics markers were associated with indices of ventricular diastolic function.

CONCLUSIONS

The majority of biatrial volumetric and functional indices were severely compromised in children with HCM compared with controls. The degree of LVOTO appears to trigger LA volumetric and LA and RA mechanical malfunction. On the other hand, the deterioration of RA volumetric components was linked to LV fibrosis and mass.

KEY POINTS

• Biatrial function was severely compromised in children with HCM. • Left atrial malfunction was associated with the degree of LVOTO. • Fibrosis and LV mass were related to RA volumetric and contractile dysfunction. • The degree of LVOTO was linked to right atrial mechanical abnormalities.

Strain imaging using cardiac magnetic resonance

The objective assessments of left ventricular (LV) and right ventricular (RV) ejection fractions (EFs) are the main important tasks of routine cardiovascular magnetic resonance (CMR). Over the years, CMR has emerged as the reference standard for the evaluation of biventricular morphology and function. However, changes in EF may occur in the late stages of the majority of cardiac diseases, and being a measure of global function, it has limited sensitivity for identifying regional myocardial impairment. On the other hand, current wall motion evaluation is done on a subjective basis and subjective, qualitative analysis has a substantial error rate. In an attempt to better quantify global and regional LV function; several techniques, to assess myocardial deformation, have been developed, over the past years. The aim of this review is to provide a comprehensive compendium of all the CMR techniques to assess myocardial deformation parameters as well as the application in different clinical scenarios.

Myocardial fibrosis evaluated by diffusion-weighted imaging and its relationship to 3D contractile function in patients with hypertrophic cardiomyopathy

BACKGROUND

Previous studies have shown that diffusion-weighted imaging (DWI) is sensitive to myocardial fibrosis in ischemic and nonischemic cardiomyopathy.

PURPOSE

To explore the prognostic value of apparent diffusion coefficient (ADC) for detecting myocardial fibrosis and its relationship to the contractile function in hypertrophic cardiomyopathy (HCM).

STUDY TYPE

Prospective.

POPULATION

A total of 45 HCM patients and 20 controls.

FIELD STRENGTH/SEQUENCE

3.0T cardiac MRI. The cardiac MR sequences included cine, T₁ mapping, and DWI.

ASSESSMENT

According to the presence of late gadolinium enhancement (LGE) and the extracellular volume (ECV) values (+2 SD of control subjects), respectively, reader W and reader J assessed the value of ADC of each segment for detecting myocardial fibrosis and its relationship to impaired contractile function in HCM patients.

STATISTICAL TESTS

Independent sample t-test, Pearson analysis, and intraclass correlation (ICC).

RESULTS

The value of ECV was 23.6 ± 3.0% for control. ECV ≥ 29.6% and ECV < 29.6% groups were classified. ADC values in the ECV ≥ 29.6% group were significantly increased compared to the ECV < 29.6% group, (2.41 ± 0.23 μm² /ms vs. 2.03 ± 0.16 μm² /ms, P < 0.005). Compared to the LGE - group, ECV (32.1 ± 2.3% vs. 29.0 ± 2.8%, P < 0.005) and ADC (2.60 ± 0.18 μm² /ms vs. 2.10 ± 0.07 μm² /ms, P < 0.005) values were significantly increased in the LGE + group. ADC values were linearly associated with ECV values (R²  = 0.65) in HCM patients. ADC values were linearly associated with circumferential and longitudinal strain (R²  = 0.60, R²  = 0.46), as well as circumferential, longitudinal, and radial strain rate (R²  = 0.13, R²  = 0.25, R²  = 0.17, respectively).

DATA CONCLUSION

Contractile dysfunction in HCM is predominantly associated with ADC, which is a feasible alternative to ECV and LGE for detecting myocardial fibrosis.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:1139-1146.

Myocardial Strain Using Cardiac MR Feature Tracking and Speckle Tracking Echocardiography in Duchenne Muscular Dystrophy Patients

Duchenne muscular dystrophy (DMD) is an inherited X-linked disorder with an incidence of 1 in 3500 male births, and cardiomyopathy is becoming the leading cause of death. While Cardiac MRI (CMR) and late gadolinium enhancement (LGE) are important tools in recognizing myocardial involvement, myocardial strain imaging may demonstrate early changes and allow patients to avoid gadolinium contrast. We performed CMR feature tracking (FT) and echo-based speckle tracking (STE) strain measures on DMD patients and age/sex matched controls who had received a CMR with contrast and transthoracic echocardiogram. Data were collected for longitudinal strain in the apical four-chamber view and circumferential strain in the mid-papillary parasternal short axis. Segmental wall analysis was performed and compared with the presence of LGE. Data were analyzed using student's t tests or one-way ANOVA adjusting for multiple comparisons. We measured 24 subjects with DMD and 8 controls. Thirteen of 24 DMD subjects were LGE positive only in the lateral segments in short-axis views. Average circumferential strain (CS) measured by FT was significantly decreased in DMD compared to controls (- 18.8 ± 6.1 vs. - 25.5 ± 3.2; p < 0.001) and showed significant differences in the anterolateral, inferolateral, and inferior segments. Average CS by STE trended towards significance (p = 0.06) but showed significance in only the inferior segment. FT showed significant differences in the inferolateral segment between LGE positive (- 15.5 ± 9.0) and LGE negative (- 18.2 ± 8.3) in DMD subjects compared to controls (- 28.6 ± 7.3; p ≤ 0.04). FT also showed significant differences between anteroseptal and inferolateral segments within LGE-positive (p < 0.003) and LGE-negative (p < 0.03) DMD subjects while STE did not. There were no significant differences in longitudinal strain measures. CMR-FT-derived myocardial strain was able to demonstrate differences between subjects with DMD and controls not detected by STE. FT was also able to demonstrate differences in LGE-positive and LGE-negative segments within patients with DMD. FT may be able to predict LGE-positive segments in DMD without the use of gadolinium contrast.

Left-ventricular mechanics in children with hypertrophic cardiomyopathy. CMR study

OBJECTIVES

To assess the magnitude of myocardial displacement abnormalities and their alterations with the fibrosis, left-ventricular (LV) outflow tract obstruction (LVOTO) and hypertrophy in juveniles with hypertrophic cardiomyopathy (HCM).

STUDY DESIGN

Fifty-five children [age 12,5±4.6years, 38 (69,1%) males, 19 (34,5%) with LVOTO] with HCM and 20 controls underwent cardiovascular magnetic resonance. The LV feature tracking (FT) derived strain and strain rates were quantified. Results of FT analysis were compared between HCM subjects and controls and between children with and without LVOTO.

RESULTS

Children with HCM exhibited decreased strain in both hypertrophied and nonhypertrophied segments versus controls. LV global longitudinal strain (LVGLS) rate (-0.69±0.04 vs -0.91±0.05, p=0,04), LV circumferential strain (LVCR) rate (-0.98±0.09 vs -1.27±0.06, p=0,02), LV radial strain (LVR) (18,5±1.9 vs 27,4±1.4, p<0,01) and LVR rate (0,98±0.1 vs 1,53±0.08, p<0,01) were substantially compromised in subjects with LVOTO vs without. In multivariable regression all LV myocardial dynamics markers, except for LVCR, exhibited a significant association with the degree of LVOTO. LVCR rate (β=0,31, p=0,02) and LVR (β=-0.24, p=0,04) were related to LV mass and only LVCR rate (β=0,15, p=0,03) was associated with the amount of LV fibrosis.

CONCLUSIONS

The reduction of all indices of LV myocardial mechanics in juvenile HCM patients was global but particularly pronounced in hypertrophied segments of the LV. The majority of the LV strains and strain rates were substantially compromised in subjects with LVOTO compared to patients without the obstruction. Myocardial mechanics indices seemed to be related to the degree of LVOTO rather than either to mass or the amount of fibrosis.

Cardiovascular magnetic resonance imaging to assess myocardial fibrosis in valvular heart disease

The left ventricular (LV) remodeling process associated with significant valvular heart disease (VHD) is characterized by an increase of myocardial interstitial space with deposition of collagen and loss of myofibers. These changes occur before LV systolic function deteriorates or the patient develops symptoms. Cardiovascular magnetic resonance (CMR) permits assessment of reactive fibrosis, with the use of T1 mapping techniques, and replacement fibrosis, with the use of late gadolinium contrast enhancement. In addition, functional consequences of these structural changes can be evaluated with myocardial tagging and feature tracking CMR, which assess the active deformation (strain) of the LV myocardium. Several studies have demonstrated that CMR techniques may be more sensitive than the conventional measures (LV ejection fraction or LV dimensions) to detect these structural and functional changes in patients with severe left-sided VHD and have shown that myocardial fibrosis may not be reversible after valve surgery. More important, the presence of myocardial fibrosis has been associated with lesser improvement in clinical symptoms and recovery of LV systolic function. Whether assessment of myocardial fibrosis may better select the patients with severe left-sided VHD who may benefit from surgery in terms of LV function and clinical symptoms improvement needs to be demonstrated in prospective studies. The present review article summarizes the current status of CMR techniques to assess myocardial fibrosis and appraises the current evidence on the use of these techniques for risk stratification of patients with severe aortic stenosis or regurgitation and mitral regurgitation.

Early marker of regional left ventricular deformation in patients with hypertrophic cardiomyopathy evaluated by MRI tissue tracking: The effects of myocardial hypertrophy and fibrosis

PURPOSE

To evaluate the regional left ventricular (LV) myocardial strain of early stage hypertrophic cardiomyopathy (HCM) patients by magnetic resonance (MR) tissue tracking.

MATERIALS AND METHODS

In all, 114 adult HCM patients classified as NYHA I or II and 32 healthy volunteers were enrolled and underwent 3.0T MR examination. Vertical 2-chamber long axis, horizontal 4-chamber, and short axis cine sequence as well as late gadolinium enhancement images (LGE) were scanned. The cardiac function, regional LV tissue tracking variables, end-diastolic wall thickness (EDTH), and LGE extent were measured.

RESULTS

In the HCM group, 38 were NYHA I and 76 were NYHA II. By regional analysis, peak strain (PS) and peak displacement (PD) with radial, circumferential direction of hypertrophic segments (n = 283) were significantly lower than nonhypertrophic segments (n = 1541) (all P < 0.05). Radial PS was significantly correlated with LVEDTH (r = -0.467, P < 0.0001). Radial PD was negatively associated with LVEDTH (r = -0.331, P < 0.0001). The PS and PD of all directions were decreased in segments with LGE (n = 723) compared with those without LGE (n = 1101) (all P < 0.05). In addition, radial PS and PD were negatively associated with LGE extent (radial PS, r = -0.441; radial PD, r = -0.274; both P < 0.0001). All strain parameters showed excellent inter- and intraobserver agreements.

CONCLUSION

Decreased regional LV myocardial strain hypertrophic and fibrotic segments of early-stage HCM patients can be measured by MR tissue tracking based on routine cine images. Moreover, myocardial strain may decrease with the increasing of myocardial hypertrophy as well as fibrosis.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1368-1376.

Advances in pediatric cardiac MRI

PURPOSE OF REVIEW

Spurred by numerous recent technological advances, cardiac MRI (CMR) is now the gold standard for anatomic evaluation, quantitative assessment of chamber size and function, flow quantification, and tissue characterization. This review focuses on recent advances in pediatric and congenital CMR, highlighting recent safety data, and discussing future directions.

RECENT FINDINGS

CMR has become an important component of risk stratification and procedural planning in numerous congenital and pediatric heart diseases. Innovative approaches to image acquisition and reconstruction are leading the way toward fast, high-resolution, three- and four-dimensional datasets for delineation of cardiac anatomy, function, and flow. In addition, techniques for assessing the composition of the myocardium may help elucidate the pathophysiology of late complications, identify patients at risk for heart failure, and assist in the evaluation of therapeutic strategies.

SUMMARY

CMR provides invaluable morphologic, hemodynamic, and functional data that help guide diagnosis, assessment, and management of pediatric and adult congenital heart disease. As imaging techniques advance and data accumulate on the relative and additive value of CMR in patient care, its role in a multimodality approach to the care of this population of patients is becoming clear and is likely to continue to evolve.