The diagnosis of hypertrophic cardiomyopathy by cardiovascular magnetic resonance

Prognostic Implications of Left Ventricular Hypertrophy and Mechanical Function in Fabry Disease: A Longitudinal Cohort Study

BACKGROUND

The prognostic value of different grades of left ventricular hypertrophy (LVH) and left ventricular (LV) mechanical function in Fabry disease is unclear. We aimed to evaluate the association between the severity of LVH, LV mechanical function, and clinical outcomes in Fabry disease.

METHODS

We conducted a retrospective cohort study from a single-center registry of adult patients with Fabry disease. Left ventricular mass index (LVMI) was measured by echocardiography. The severity of LVH was categorized by LVMI using the sex-specific cutoff values. Left ventricular mechanical function was measured as LV global longitudinal strain (GLS) by speckle-tracking analysis. The primary outcome was a composite of major adverse cardiovascular events (MACE) at 5 years, including heart failure hospitalization, sustained ventricular tachycardia, acute ischemic stroke, and all-cause mortality.

RESULTS

The study included 268 patients (age 50.4 ± 15.4 years, men 46.6%) with Fabry disease (83.2% IVS4+919G > A mutation), and 106 patients (39.6%) had LVH. Patients with mild, moderate, or severe LVH had 5-year MACE rates of 7.4%, 10%, and 30.5%, respectively (P < .001). Moreover, patients with impaired LV GLS (<14.1%) had a higher 5-year MACE rate than those with preserved LV GLS (32.1% vs 2.4%, P < .001). Severe LVH was an independent predictor of MACE compared with absence of LVH (adjusted hazard ratio, 12.73; 95% CI, 1.3-124.71; P = .03), after adjusting for age, sex, hypertension, hyperlipidemia, atrial fibrillation, renal function, average E/e', enzyme replacement therapy, and LV GLS. Patients with severe LVH and impaired LV GLS had the highest incidence for MACE (log-rank P < .05), irrespective of sex, genotypes, and whether receiving enzyme replacement therapy or not.

CONCLUSIONS

Sex-specific grading of LVH by LVMI is practical for risk stratification in patients with Fabry disease, and impaired LV GLS further refines the prognostication.

Shifting paradigms in hypertrophic cardiomyopathy: the role of exercise in disease management

Hypertrophic cardiomyopathy (HCM) is traditionally associated with exercise restriction due to potential risks, yet recent evidence and guidelines suggest a more permissive stance for low-risk individuals. The aim of this comprehensive review was to examine existing research on the impact of exercise on cardiovascular outcomes, safety, and quality of life in this population and to consider implications for clinical practice. Recent studies suggest that regular exercise and physical activity in low-risk individuals with HCM are associated with positive outcomes in functional capacity, haemodynamic response, and quality of life, with consistent safety. Various studies highlight the safety of moderate-intensity exercise, showing improvements in exercise capacity without adverse cardiac remodelling or significant arrhythmias. Psychological benefits, including reductions in anxiety and depression, have been also reported following structured exercise programmes. These findings support the potential benefits of integrating individualised exercise regimens in the management of low-risk individuals with HCM, with the aim of improving their overall well-being and cardiovascular health. Adoption of the FITT (frequency, intensity, time, and type of exercise) principle, consideration of individual risk profiles, and shared decision-making are recommended. Future research is warranted to clarify the definition of 'low risk' for exercise participation and investigate the influence of physical activity on disease progression in HCM. Innovation in therapeutic strategies and lifestyle interventions, alongside improved patient and provider education, will help advance the care and safety of individuals with HCM engaging in exercise.

Cardiovascular Magnetic Resonance Imaging in Myocardial Disease

Cardiovascular magnetic resonance (CMR) is the central non-invasive imaging investigation for the evaluation of myocardial disease. It is the well-established gold standard for measuring cardiac chamber volumes, systolic function, and left ventricular mass, and it brings unique information for therapeutic decisions. In addition, its tissue characterization capability, through T1, T2, and T2* mapping, as well as early and late gadolinium enhancement (LGE) sequences, allows to differentiate in many cases among ischemic, inflammatory, and infiltrative heart disease and permits the quantification of myocardial fibrosis, providing valuable diagnostic and prognostic information. This review aims to highlight the main CMR features of different cardiomyopathies.

Cardiac Magnetic Resonance Feature-Tracking Identifies Preclinical Abnormalities in Hypertrophic Cardiomyopathy Sarcomere Gene Mutation Carriers

BACKGROUND

Assessing myocardial strain by cardiac magnetic resonance feature tracking (FT) has been found to be useful in patients with overt hypertrophic cardiomyopathy (HCM). Little is known, however, of its role in sarcomere gene mutation carriers without overt left ventricular hypertrophy (subclinical HCM).

METHODS

Thirty-eight subclinical HCM subjects and 42 healthy volunteers were enrolled in this multicenter case-control study. They underwent a comprehensive cardiac magnetic resonance study. Two-dimensional global radial, circumferential, and longitudinal strain of the left ventricle (LV) were evaluated by FT analysis.

RESULTS

The subclinical HCM sample was 41 (22-51) years old and 32% were men. FT analysis revealed a reduction in global radial strain (29±7.2 versus 47.9±7.4; P<0.0001), global circumferential strain (-17.3±2.6 -versus -20.8±7.4; P<0.0001) and global longitudinal strain (-16.9±2.4 versus -20.5±2.6; P<0.0001) in subclinical HCM compared with control subjects. The significant differences persisted when considering the 23 individuals free of all the structural and functional ECG and cardiac magnetic resonance abnormalities previously described. Receiver operating characteristic curve analyses showed that the differential diagnostic performances of FT in discriminating subclinical HCM from normal subjects were good to excellent (global radial strain with optimal cut-off value of 40.43%: AUC, 0.946 [95% CI, 0.93-1.00]; sensitivity 90.48%, specificity 94.44%; global circumferential strain with cut-off, -18.54%: AUC, 0.849 [95% CI, 0.76-0.94]; sensitivity, 88.10%; specificity, 72.22%; global longitudinal strain with cut-off, -19.06%: AUC, 0.843 [95% CI, 0.76-0.93]; sensitivity, 78.57%; specificity, 78.95%). Similar values were found for discriminating those subclinical HCM subjects without other phenotypic abnormalities from healthy volunteers (global radial strain with optimal cut-off 40.43%: AUC, 0.966 [95% CI, 0.92-1.00]; sensitivity, 90.48%; specificity, 95.45%; global circumferential strain with cut-off, -18.44%: AUC, 0.866 [95% CI, 0.76-0.96]; sensitivity, 92.86%; specificity, 77.27%; global longitudinal strain with cut-off, -17.32%: AUC, 0.838 [95% CI, 0.73-0.94]; sensitivity, 90.48%; specificity, 65.22%).

CONCLUSIONS

Cardiac magnetic resonance FT-derived parameters are consistently lower in subclinical patients with HCM, and they could emerge as a good tool for discovering the disease during a preclinical phase.

Role of Imaging in the Diagnosis, Evaluation, and Management of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is increasingly recognized and may benefit from the recent approval of new, targeted medical therapy. Successful management of HCM is dependent on early and accurate diagnosis. The lack of a definitive diagnostic test, the wide variation in phenotype and the commonness of phenocopy conditions, and the presence of normal or hyperdynamic left ventricular function in most patients makes HCM a condition that is highly dependent on imaging for all aspects of management including, diagnosis, classification, predicting risk of complications, detecting complications, identifying risk for ventricular arrhythmias, evaluating choice of therapy and monitoring therapy, intraprocedural guidance, and screening family members. Although echocardiographic imaging remains the mainstay in the diagnosis and subsequent management of HCM, this disease clearly requires multimethod imaging for various aspects of optimal patient care. Advances in echocardiography hardware and techniques, development and refinement of imaging with computed tomography, magnetic resonance, and nuclear scanning, and the emergence of very focused assessments such as diastology and fibrosis imaging have all advanced the diagnosis and management of HCM. In this review, we discuss the relative utility and evidence support for these imaging approaches to contribute to improve patient outcomes.

Impact of a Center of Excellence in Confirming or Excluding a Diagnosis of Hypertrophic Cardiomyopathy

Tertiary hospitals with expertise in hypertrophic cardiomyopathy (HCM) are assuming a greater role in confirming and correcting HCM diagnoses at referring centers. The objectives were to establish the frequency of alternate diagnoses from referring centers and identify predictors of accuracy of an HCM diagnosis from the referring centers. Imaging findings from echocardiography, cardiac computed tomography, and cardiac magnetic resonance imaging (CMR) in 210 patients referred to an HCM Center of Excellence between September 2020 and October 2022 were reviewed. Clinical and imaging characteristics from pre-referral studies were used to construct a model for predictors of ruling out HCM or confirming the diagnosis using machine learning methods (least absolute shrinkage and selection operator logistic regression). Alternative diagnoses were found in 38 of the 210 patients (18.1%) (median age 60 years, 50% female). A total of 17 of the 38 patients (44.7%) underwent a new CMR after their initial visit, and 14 of 38 patients (36.8%) underwent review of a previous CMR. Increased left ventricular end-diastolic volume, indexed, greater septal thickness measurements, greater left atrial size, asymmetric hypertrophy on echocardiography, and the presence of an implantable cardioverter-defibrillator were associated with higher odds ratios for confirming a diagnosis of HCM, whereas increasing age and the presence of diabetes were more predictive of rejecting a diagnosis of HCM (area under the curve 0.902, p <0.0001). In conclusion, >1 in 6 patients with presumed HCM were found to have an alternate diagnosis after review at an HCM Center of Excellence, and both clinical findings and imaging parameters predicted an alternate diagnosis.

Mid-cavitary hypertrophy after myocarditis in a patient with operated medulloblastoma

A 16-month-old girl was referred for tachycardia and upper respiratory tract infection. Echocardiographic examination revealed pericardial effusion, mild mitral regurgitation, and left ventricle systolic dysfunction. Patient was positive for Parainfluenza type 4 virus. Her laboratory tests revealed increased troponin I level. The patient was treated with intravenous immunoglobulin considering acute viral myopericarditis. Two weeks after treatment, midventricular hypertrophy was detected.

LGE prevalence and patterns in severe aortic stenosis: When "junctional" means the same

BACKGROUND

Left ventricular (LV) remodeling in severe aortic valve stenosis (AS) is a complex process that goes beyond hypertrophic response. Reparative/replacement fibrosis is considered irreversible and has recognized value in both risk stratification and prognosis. Currently, cardiac magnetic resonance (CMR) is the gold-standard imaging technique for fibrosis identification through late gadolinium enhancement (LGE) assessment. However, its prevalence and distribution are quite variable among series. Our goal was to assess LGE prevalence and patterns in severe AS.

METHODOLOGY

Single-center prospective cohort of 140 patients with severe symptomatic high-gradient AS (mean age 72 ± 8 years; mean valvular transaortic gradient 61 ± 18 mmHg; mean LV ejection fraction by echocardiogram 58 ± 9%) undergoing surgical aortic valve replacement. Those with previous myocardial infarction and/or non-ischemic cardiomyopathy were excluded. All patients performed 1.5 T LGE-CMR prior to surgery.

RESULTS

Overall, 103 patients (74%) had non-ischemic LGE (median LGE mass 2.8 g [IQR 0.0-7.8] g), many of them with combined mid-wall and junctional enhancement pattern (36%). LGE was most frequently observed in the mid-basal segments of the interventricular septum. Seventy-four patients (53%) had non-exclusively junctional LGE. Contrary to those with junctional enhancement, patients with non-exclusively junctional LGE had higher LV volumes/mass, worse LV ejection fraction and worse global longitudinal strain.

CONCLUSION

Among patients with severe, symptomatic, high-gradient AS, LGE is frequent, primarily affecting the mid-basal interventricular septum. Contrary to junctional LGE, the presence of non-junctional LGE seems to correlate with adverse markers of LV remodeling.

Magnetic Resonance Left Ventricle Mass-Index/Fibrosis: Long-Term Predictors for Ventricular Arrhythmia in Hypertrophic Cardiomyopathy—A Retrospective Registry

Objective: We aimed to study the long-term association of LV mass index (LVMI) and myocardial fibrosis with ventricular arrhythmia (VA) in a population of patients with confirmed hypertrophic cardiomyopathy (HCM) using cardiac magnetic resonance imaging (CMR). Methods: We retrospectively analyzed the data in consecutive HCM patients confirmed on CMR referred to an HCM clinic between January 2008 and October 2018. Patients were followed up yearly following diagnosis. Baseline demographics, risk factors and clinical outcomes from cardiac monitoring and an implanted cardioverter defibrillator (ICD) were analyzed for association of LVMI and LV late gadolinium enhancement (LVLGE) with VA. Patients were then allocated to one of two groups according to the presence of VA (Group A) or absence of VA (Group B) during the follow-up period. The transthoracic echocardiogram (TTE) and CMR parameters were compared between the two groups. Results: A total of 247 patients with confirmed HCM (age 56.2 ± 16.6, male = 71%) were studied over the follow-up period of 7 ± 3.3 years (95% CI = 6.6–7.4 years). LVMI derived from CMR was higher in Group A (91.1 ± 28.1 g/m2 vs. 78.8 ± 28.3 g/m2, p = 0.003) when compared to Group B. LVLGE was higher in Group A (7.3 ± 6.3% vs. 4.7 ± 4.3%, p = 0.001) when compared to Group B. Multivariable Cox regression analysis showed LVMI (hazard ratio (HR) = 1.02, 95% CI = 1.001–1.03, p = 0.03) and LVLGE (HR = 1.04, 95% CI = 1.001–1.08, p = 0.04) to be independent predictors for VA. Receiver operative curves showed higher LVMI and LVLGE with a cut-off of 85 g/m2 and 6%, respectively, to be associated with VA. Conclusions: LVMI and LVLGE are strongly associated with VA over long-term follow-up. LVMI requires more thorough studies to consider it as a risk stratification tool in patients with HCM.

Hypertrophic cardiomyopathy - phenotypic variations beyond wall thickness

Hypertrophic cardiomyopathy (HCM) is characterized by left ventricular hypertrophy (LVH) in the absence of another causal disease. Several morphologic and histologic changes have been described. Given the morbidity and mortality associated with HCM, understanding these anatomic variations is key to interpreting imaging. This is especially important since many patients exhibit these associated findings in the absence of LVH and prompt early detection of these variations may lead to early diagnosis and treatment. This article describes the appearance of morphologic variations seen in HCM beyond myocardial thickening including: papillary muscle and mitral valve variants, myocardial crypts, left ventricular myocardial bands, and dystrophic calcification related to increased wall tension.

Risk stratification in patients with hypertrophic cardiomyopathy: Looking beyond the left side myocardial function

BACKGROUND

Patients with hypertrophic cardiomyopathy (HCM) have heterogeneous outcomes. As risk stratification mostly focuses on left-side myocardial function, we sought to investigate the prognostic value of right ventricular (RV) function in patients with HCM.

METHODS

This retrospective cohort study included patients with HCM. Conventional ventricular functional parameters, including left ventricular ejection fraction (LVEF), tricuspid annular plane systolic excursion (TAPSE), and fractional area change were obtained. The longitudinal strain was analyzed using the speckle tracking method. The primary endpoint was defined as a composite of hospitalization for heart failure, sustained ventricular tachycardia, or all-cause death.

RESULTS

A total of 56 patients with HCM (aged 58.0 ± 14.9 years, 64.3% male) were included. After a mean follow-up duration of 30.1 ± 17.4 months, primary endpoints developed in 10 (20%) of 50 patients who were treated medically. Patients with cardiovascular events had a more reduced LV thickest segmental strain, worse TAPSE, and more impaired RV free wall strain. After adjusting for age, sex, and LVEF, TAPSE (hazard ratio [HR], 95% confidence intervals [CIs]: 0.24, 0.06-0.93) and RV free wall strain (HR, 95% CIs:1.12, 1.03-1.21) remained independent prognostic predictors. Incorporating either TAPSE or RV free wall strain provides incremental prognostic value to the LV strain alone (net reclassification improvement by 31.4% and 34.1%, respectively, both p < 0.05).

CONCLUSION

RV function assessed by TAPSE or RV free wall strain is predictive of subsequent cardiac events, suggesting that a comprehensive evaluation of RV function is useful for risk stratification in patients with HCM.

Tale of two hearts: a TNNT2 hypertrophic cardiomyopathy case report

Hypertrophic cardiomyopathy (HCM) is a heritable cardiomyopathy that is predominantly caused by pathogenic mutations in sarcomeric proteins. Here we report two individuals, a mother and her daughter, both heterozygous carriers of the same HCM-causing mutation in cardiac Troponin T (TNNT2). Despite sharing an identical pathogenic variant, the two individuals had very different manifestations of the disease. While one patient presented with sudden cardiac death, recurrent tachyarrhythmia, and findings of massive left ventricular hypertrophy, the other patient manifested with extensive abnormal myocardial delayed enhancement despite normal ventricular wall thickness and has remained relatively asymptomatic. Recognition of the marked incomplete penetrance and variable expressivity possible in a single TNNT2-positive family has potential to guide HCM patient care.

An artificial intelligence-enabled ECG algorithm for identifying ventricular premature contraction during sinus rhythm

Background

Ventricular premature complex (VPC) is a common arrhythmia in clinical practice. VPC could trigger ventricular tachycardia/fibrillation or VPC-induced cardiomyopathy in susceptible patients. Existing screening methods require prolonged monitoring and are limited by cost and low yield when the frequency of VPC is low. Twelve-lead electrocardiogram (ECG) is low cost and widely used. We aimed to identify patients with VPC during normal sinus rhythm (NSR) using artificial intelligence (AI) and machine learning-based ECG reading.

Methods

We developed AI-enabled ECG algorithm using a convolutional neural network (CNN) to detect the ECG signature of VPC presented during NSR using standard 12-lead ECGs. A total of 2515 ECG records from 398 patients with VPC were collected. Among them, only ECG records of NSR without VPC (1617 ECG records) were parsed.

Results

A total of 753 normal ECG records from 387 patients under NSR were used for comparison. Both image and time-series datasets were parsed for the training process by the CNN models. The computer architectures were optimized to select the best model for the training process. Both the single-input image model (InceptionV3, accuracy: 0.895, 95% confidence interval [CI] 0.683–0.937) and multi-input time-series model (ResNet50V2, accuracy: 0.880, 95% CI 0.646–0.943) yielded satisfactory results for VPC prediction, both of which were better than the single-input time-series model (ResNet50V2, accuracy: 0.840, 95% CI 0.629–0.952).

Conclusions

AI-enabled ECG acquired during NSR permits rapid identification at point of care of individuals with VPC and has the potential to predict VPC episodes automatically rather than traditional long-time monitoring.

Differential Diagnosis of Thick Myocardium according to Histologic Features Revealed by Multiparametric Cardiac Magnetic Resonance Imaging

Left ventricular (LV) wall thickening, or LV hypertrophy (LVH), is common and occurs in diverse conditions including hypertrophic cardiomyopathy (HCM), hypertensive heart disease, aortic valve stenosis, lysosomal storage disorders, cardiac amyloidosis, mitochondrial cardiomyopathy, sarcoidosis and athlete’s heart. Cardiac magnetic resonance (CMR) imaging provides various tissue contrasts and characteristics that reflect histological changes in the myocardium, such as cellular hypertrophy, cardiomyocyte disarray, interstitial fibrosis, extracellular accumulation of insoluble proteins, intracellular accumulation of fat, and intracellular vacuolar changes. Therefore, CMR imaging may be beneficial in establishing a differential diagnosis of LVH. Although various diseases share LV wall thickening as a common feature, the histologic changes that underscore each disease are distinct. This review focuses on CMR multiparametric myocardial analysis, which may provide clues for the differentiation of thickened myocardium based on the histologic features of HCM and its phenocopies.

Artificial intelligence study on left ventricular function among normal individuals, hypertrophic cardiomyopathy and dilated cardiomyopathy patients using 1.5T cardiac cine MR images obtained by SSFP sequence

OBJECTIVES

To evaluate the performance of a deep learning-based method to automatically quantify left ventricular (LV) function from MR images in different cardiomyopathy.

METHODS

This retrospective study included MRI data sets from 2013 to 2020. Data on left ventricular function from patients with hypertrophic cardiomyopathy (HCM), patients with dilated cardiomyopathy (DCM), and healthy participants were analyzed. MRI data from a total of 388 patients were measured manually and automatically.The performance of Convolutional Neural Networks (CNNs) was evaluated based on the manual notes of two experienced observers: (a) LV segmentation accuracy, and (b) LV functional parameter accuracy. Bland-Altman analysis, Receiver operating Characteristic (ROC) curve analysis and Pearson correlation analysis were used to evaluate the consistency between fully automatic and manual diagnosis of HCM and DCM.

RESULTS

The deep-learning CNN performed best in HCM in evaluating LV function and worst in DCM. Compared with manual analysis, four parameters of LV function in the HCM group showed high correlation (r at least >0.901), and the correlation of DCM in all parameters was weaker than that of HCM, especially EF (r2 = 0.776) and SV (r2 = 0.645). ROC curve analysis indicated that at the optimal cut-off value, EF from automatic segmentation identified DCM and HCM patients with sensitivity of 92.31 and 78.05%, specificity of 82.96 and 54.07%, respectively.

CONCLUSION

Among different heart diseases, the analysis of cardiac function based on deep-learning CNN may have different performances, with DCM performing the worst and HCM the best and thus, special attention should be paid to DCM patients when assessing LV function through artificial intelligence method. LV function parameter obtained by artificial intelligence method may play an important role in the future AI diagnosis of HCM and DCM.

ADVANCES IN KNOWLEDGE

These data for the first time objectively evaluate the performance of a commercially available deep learning-based method in cardiac function evaluation of different cardiomyopathy and point out its advantages and disadvantages in different cardiomyopathy. This work did not attempt to design the algorithm itself, but rather applied an already existing method to a test dataset of clinical data and evaluated the results for a limited number of cardiomyopathy.

The Role of Cardiovascular Magnetic Resonance Imaging in the Evaluation of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disorder, affecting 1 out of 500 adults globally. It is a widely heterogeneous disorder characterized by a range of phenotypic expressions, and is most often identified by non-invasive imaging that includes echocardiography and cardiovascular magnetic resonance imaging (CMR). Within the last two decades, cardiac magnetic resonance imaging (MRI) has emerged as the defining tool for the characterization and prognostication of cardiomyopathies. With a higher image quality, spatial resolution, and the identification of morphological variants of HCM, CMR has become the gold standard imaging modality in the assessment of HCM. Moreover, it has been crucial in its management, as well as adding prognostic information that clinical history nor other imaging modalities may not provide. This literature review addresses the role and current applications of CMR, its capacity in evaluating HCM, and its limitations.

Novel Morphological Features on CMR for the Prediction of Pathogenic Sarcomere Gene Variants in Subjects Without Hypertrophic Cardiomyopathy

Background: Carriers of pathogenic DNA variants (G+) causing hypertrophic cardiomyopathy (HCM) can be identified by genetic testing. Several abnormalities have been brought forth as pre-clinical expressions of HCM, some of which can be identified by cardiovascular magnetic resonance (CMR). In this study, we assessed morphological differences between G+/left ventricular hypertrophy-negative (LVH-) subjects and healthy controls and examined whether CMR-derived variables are useful for the prediction of sarcomere gene variants.

Methods: We studied 57 G+ subjects with a maximal wall thickness (MWT) < 13 mm, and compared them to 40 healthy controls matched for age and sex on a group level. Subjects underwent CMR including morphological, volumetric and function assessment. Logistic regression analysis was performed for the determination of predictive CMR characteristics, by which a scoring system for G+ status was constructed.

Results: G+/LVH- subjects were subject to alterations in the myocardial architecture, resulting in a thinner posterior wall thickness (PWT), higher interventricular septal wall/PWT ratio and MWT/PWT ratio. Prominent hook-shaped configurations of the anterobasal segment were only observed in this group. A model consisting of the anterobasal hook, multiple myocardial crypts, right ventricular/left ventricular ratio, MWT/PWT ratio, and MWT/left ventricular mass ratio predicted G+ status with an area under the curve of 0.92 [0.87–0.97]. A score of ≥3 was present only in G+ subjects, identifying 56% of the G+/LVH- population.

Conclusion: A score system incorporating CMR-derived variables correctly identified 56% of G+ subjects. Our results provide further insights into the wide phenotypic spectrum of G+/LVH- subjects and demonstrate the utility of several novel morphological features. If genetic testing for some reason cannot be performed, CMR and our purposed score system can be used to detect possible G+ carriers and to aid planning of the control intervals.

Obstructive and Nonobstructive Hypertrophic Cardiomyopathy: Differences in Global and Segmental Myocardial Strain by Cardiac Magnetic Resonance Feature Tracking

PURPOSE

To evaluate any significant differences in myocardial strain between hypertrophic obstructive cardiomyopathy (HOCM) and nonobstructive ones (HNCM), as assessed by cardiac magnetic resonance feature tracking (CMR-FT).

MATERIALS AND METHODS

A total of 17 patients (mean age: 54±14 y) with echocardiographic diagnosis of HOCM (left ventricular outflow tract obstruction peak gradient ≥30 mm Hg), 19 patients (mean age: 49±16 y) with HNCM (peak gradient <30 mm Hg), and 18 age-matched and gender-matched healthy controls (mean age: 42±14 y). All patients underwent cardiac MRI with SSFP-cine to assess left ventricular global and segmental strain analysis by CMR-FT. Late gadolinium enhancement (LGE) sequences were used for semiautomatic quantification of LGE volume, mass, and percentage.

RESULTS

The magnitude of global radial, circumferential, and longitudinal strain as well as strain rate were significantly lower in all patients in comparison to controls (P<0.001), except for radial and circumferential strain between HOCM and controls (P=0.270; P=0.154). The latter strain parameters were significantly higher in HOCM than HNCM (radial strain: 31.67±7.55 vs. 21.26±7.10, P<0.001; circumferential strain: -17.94±2.78 vs. -13.46±3.42, P<0.001). Radial and circumferential strain and circumferential diastolic strain rate were higher in mid-anterior (P<0.001), mid-anteroseptal (P<0.001), and all apical segments (P<0.005) between the 2 groups of patients. Moreover, longitudinal strain was higher only in apical segments in HOCM (P<0.02).

CONCLUSIONS

HOCM patients showed higher left ventricular apical, mid-anterior, and mid-anteroseptal strain parameters compared with HNCM. These differences were independent of corresponding segmental thickness and LGE amount.

Multi-parametric assessment of left ventricular hypertrophy using late gadolinium enhancement, T1 mapping and strain-encoded cardiovascular magnetic resonance

AIM

To evaluate the ability of single heartbeat fast-strain encoded (SENC) cardiovascular magnetic resonance (CMR) derived myocardial strain to discriminate between different forms of left ventricular (LV) hypertrophy (LVH).

METHODS

314 patients (228 with hypertensive heart disease (HHD), 45 with hypertrophic cardiomyopathy (HCM), 41 with amyloidosis, 22 competitive athletes, and 33 healthy controls) were systematically analysed. LV ejection fraction (LVEF), LV mass index and interventricular septal (IVS) thickness, T1 mapping and atypical late gadolinium enhancement (LGE) were assessed. In addition, the percentage of LV myocardial segments with strain ≤ - 17% (%normal myocardium) was determined.

RESULTS

Patients with amyloidosis and HCM exhibited the highest IVS thickness (17.4 ± 3.3 mm and 17.4 ± 6 mm, respectively, p < 0.05 vs. all other groups), whereas patients with amyloidosis showed the highest LV mass index (95.1 ± 20.1 g/m2, p < 0.05 vs all others) and lower LVEF compared to controls (50.5 ± 9.8% vs 59.2 ± 5.5%, p < 0.05). Analysing subjects with mild to moderate hypertrophy (IVS 11-15 mm), %normal myocardium exhibited excellent and high precision, respectively for the differentiation between athletes vs. HCM (sensitivity and specificity = 100%, Area under the curve; AUC%normalmyocardium = 1.0, 95%CI = 0.85-1.0) and athletes vs. HHD (sensitivity = 83%, specificity = 75%, AUC%normalmyocardium = 0.85, 95%CI = 0.78-0.90). Combining %normal myocardial strain with atypical LGE provided high accuracy also for the differentiation of HHD vs. HCM (sensitivity = 82%, specificity = 100%, AUCcombination = 0.92, 95%CI = 0.88-0.95) and HCM vs. amyloidosis (sensitivity = 83%, specificity = 100%, AUCcombination = 0.83, 95%CI = 0.60-0.96).

CONCLUSION

Fast-SENC derived myocardial strain is a valuable tool for differentiating between athletes vs. HCM and athletes vs. HHD. Combining strain and LGE data is useful for differentiating between HHD vs. HCM and HCM vs. cardiac amyloidosis.

Prevalence and prognostic impact of nonischemic late gadolinium enhancement in stress cardiac magnetic resonance

AIM

To assess the prevalence and prognostic significance of NI-LGE in patients undergoing stress-CMR.

METHODS

Stress-CMR with either dipyridamole or adenosine was performed in 283 patients (228 men, 81%) including perfusion imaging, wall motion evaluation and LGE. Follow-up was completed in all enrolled patients (median time: 1850 days; interquartile range: 1225-2705 days). Composite endpoint included cardiac death, ventricular tachycardia, myocardial infarction, stroke, hospitalization for cardiac cause and coronary revascularization performed beyond 90 days from stress-CMR scans.

RESULTS

One hundred and twelve patients (40%) had negative LGE (no-LGE), 140 patients (49%) I-LGE and 31 patients (11%) NI-LGE. Twenty-five events occurred in the no-LGE group, 68 in I-LGE and 11 in the NI-LGE group. On survival curves, patients with NI-LGE had worse prognosis than patients with no-LGE regardless of the presence of inducible perfusion defects. No significant prognostic differences were found between I-LGE and NI-LGE.

CONCLUSION

NI-LGE can be detected in 11% of patients during stress-CMR providing a diagnosis of nonischemic cardiac disease. Patients with NI-LGE have worse prognosis than those with no-LGE.

Hypertrophic Cardiomyopathy and Primary Restrictive Cardiomyopathy: Similarities, Differences and Phenocopies

Hypertrophic cardiomyopathy (HCM) and primary restrictive cardiomyopathy (RCM) have a similar genetic background as they are both caused mainly by variants in sarcomeric genes. These “sarcomeric cardiomyopathies” also share diastolic dysfunction as the prevalent pathophysiological mechanism. Starting from the observation that patients with HCM and primary RCM may coexist in the same family, a characteristic pathophysiological profile of HCM with restrictive physiology has been recently described and supports the hypothesis that familiar forms of primary RCM may represent a part of the phenotypic spectrum of HCM rather than a different genetic cardiomyopathy. To further complicate this scenario some infiltrative (amyloidosis) and storage diseases (Fabry disease and glycogen storage diseases) may show either a hypertrophic or restrictive phenotype according to left ventricular wall thickness and filling pattern. Establishing a correct etiological diagnosis among HCM, primary RCM, and hypertrophic or restrictive phenocopies is of paramount importance for cascade family screening and therapy.

Free-Breathing Motion-Corrected Single-Shot Phase-Sensitive Inversion Recovery Late-Gadolinium-Enhancement Imaging: A Prospective Study of Image Quality in Patients with Hypertrophic Cardiomyopathy

Objective

Motion-corrected averaging with a single-shot technique was introduced for faster acquisition of late-gadolinium-enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging while free-breathing. We aimed to evaluate the image quality (IQ) of free-breathing motion-corrected single-shot LGE (moco-ss-LGE) in patients with hypertrophic cardiomyopathy (HCM).

Materials and Methods

Between April and December 2019, 30 patients (23 men; median age, 48.5; interquartile range [IQR], 36.5–61.3) with HCM were prospectively enrolled. Breath-held single-shot LGE (bh-ss-LGE) and free-breathing moco-ss-LGE images were acquired in random order on a 3T MR system. Semi-quantitative IQ scores, contrast-to-noise ratios (CNRs), and quantitative size of myocardial scar were assessed on pairs of bh-ss-LGE and moco-ss-LGE. The mean ± standard deviation of the parameters was obtained. The results were compared using the Wilcoxon signed-rank test.

Results

The moco-ss-LGE images had better IQ scores than the bh-ss-LGE images (4.55 ± 0.55 vs. 3.68 ± 0.45, p < 0.001). The CNR of the scar to the remote myocardium (34.46 ± 11.85 vs. 26.13 ± 10.04, p < 0.001), scar to left ventricle (LV) cavity (13.09 ± 7.95 vs. 9.84 ± 6.65, p = 0.030), and LV cavity to remote myocardium (33.12 ± 15.53 vs. 22.69 ± 11.27, p < 0.001) were consistently greater for moco-ss-LGE images than for bh-ss-LGE images. Measurements of scar size did not differ significantly between LGE pairs using the following three different quantification methods: 1) full width at half-maximum method; 23.84 ± 12.88% vs. 24.05 ± 12.81% (p = 0.820), 2) 6-standard deviation method, 15.14 ± 10.78% vs. 15.99 ± 10.99% (p = 0.186), and 3) 3-standard deviation method; 36.51 ± 17.60% vs. 37.50 ± 17.90% (p = 0.785).

Conclusion

Motion-corrected averaging may allow for superior IQ and CNRs with free-breathing in single-shot LGE imaging, with a herald of free-breathing moco-ss-LGE as the scar imaging technique of choice for clinical practice.

Angiotensin (1-7) and Apelin co-therapy: New strategy for heart failure treatment of rats

Objective:

Isoproterenol (ISO)–induced heart failure is a standardized model for the study of beneficial effects of various drugs. Both apelin and angiotensin 1–7 have a cardiac protective effect. We assumed that co–therapy with apelin and angiotensin 1–7 [Ang (1–7)] may have synergistic cardioprotective effects against isoproterenol-induced heart failure.

Methods:

The rats were randomly assigned to one of eight groups, 7 animals in each, as follows: (1) Control I (saline; IP injection), (2) Control II (saline; via mini-osmotic pump), (3) ISO (5 mg/kg; IP), (4) Apelin (20 μg/kg; IP), (5) Ang (1–7) (30 μg/kg/day; via mini-osmotic pump), (6) Apelin+ISO, (7) Ang (1–7)+ISO, and (8) Apelin+Ang (1–7)+ISO. Rat myocardial injury was induced by intraperitoneal injection of 5 mg/kg of ISO for 10 days. Apelin and Ang (1–7) were administered 30 minutes before the ISO injection.

Results:

A decrease in the systolic blood pressure [SBP (p<0.001)], diastolic blood pressure [DBP (p=0.024)], left ventricular systolic pressure [LVSP (p<0.001)], left ventricular contractility [dP/dt max. (p<0.001)], relaxation [dP/dt min. (p<0.001)], and an increase in left ventricular end-diastolic pressure [LVEDP, (p<0.001)] were observed in ISO-treated rats. Plasma LDH and myocardial and plasma MDA were higher in the ISO heart than in controls (p<0.001). Histopathological examination of the cardiac tissue showed myocardial fibrosis and leukocyte infiltration in ISO-treated rats as compared to control. Co-therapy with apelin and Ang (1–7) was more effective than either agent used alone in restoring these parameters to that of control rats.

Conclusion:

The results of this study showed that the combination of apelin and Ang (1–7) had a more cardioprotective effect than either used alone against ISO-induced heart failure, and co–therapy may be a useful treatment option for myocardial injuries and heart failure.

Cardiac Masses: The Role of Cardiovascular Imaging in the Differential Diagnosis

Cardiac masses are space occupying lesions within the cardiac cavities or adjacent to the pericardium. They include frequently diagnosed clinical entities such as clots and vegetations, common benign tumors such as myxomas and papillary fibroelastomas and uncommon benign or malignant primary or metastatic tumors. Given their diversity, there are no guidelines or consensus statements regarding the best diagnostic or therapeutic approach. In the past, diagnosis used to be made by the histological specimens after surgery or during the post-mortem examination. Nevertheless, evolution and increased availability of cardiovascular imaging modalities has enabled better characterization of the masses and the surrounding tissue. Transthoracic echocardiography using contrast agents can evaluate the location, the morphology and the perfusion of the mass as well as its hemodynamic effect. Transesophageal echocardiography has increased spatial and temporal resolution; hence it is superior in depicting small highly mobile masses. Cardiac magnetic resonance and cardiac computed tomography are complementary providing tissue characterization. The scope of this review is to present the role of cardiovascular imaging in the differential diagnosis of cardiac masses and to propose a step-wise diagnostic algorithm, taking into account the epidemiology and clinical presentation of the cardiac masses, as well as the availability and the incremental value of each imaging modality.

Two Birds With One Stone: The Decisive Role of Cardiac MRI in Identifying Both Hypertrophic Cardiomyopathy and Pericarditis Simultaneously in a Patient with Chest Pain

A 35-year-old Hispanic male presented at an outside facility with chest pain a few days after a long road trip. The initial electrocardiogram (EKG) showed sinus tachycardia with no other abnormality. His D-dimer was positive but a subsequent computed tomography angiography (CTA) of the chest was negative for pulmonary embolism. An echocardiogram showed trace pericardial effusion with a normal ejection fraction (EF) of 70% and severe asymmetric septal hypertrophy. Satisfactory Doppler signals to assess the gradient across the left ventricle outflow tract (LVOT) could not be obtained on echocardiogram. The patient was diagnosed with acute pericarditis, which was treated medically with an improvement of his symptoms. Later, he presented to our facility for an outpatient cardiac magnetic resonance (CMR) with and without contrast, which showed severe asymmetric septal hypertrophy measuring 29 mm with substantial patchy myocardial delayed enhancement and systolic anterior motion of the mitral leaflet with flow dephasing of LVOT. These findings were diagnostic of hypertrophic obstructive cardiomyopathy. CMR also showed signs consistent with pericarditis. A Holter monitor was unremarkable for arrhythmia. A stress echocardiogram did not demonstrate any drop in blood pressure during exercise. His interventricular septum measured 29 mm on cardiac magnetic resonance imaging (MRI), which was very close to the 30 mm cut-off for an implantable cardioverter-defibrillator (ICD). In addition, he had a marked delayed enhancement in the hypertrophied septum due to gadolinium uptake, which is also considered a high-risk feature for sudden cardiac death. After discussions between the patient, cardiologist, cardiac imaging specialist, and electrophysiologist, a subcutaneous ICD was pursued, which was successfully implanted. He was started on medical treatment. He was followed closely in the clinic and has remained asymptomatic for the past two years.

Analysis of three-chamber view conventional and tagged cine MRI in patients with suspected hypertrophic cardiomyopathy

OBJECTIVES

To investigate the potential value of adding a tagged three-chamber (3Ch) cine to clinical hypertrophic cardiomyopathy (HCM) magnetic resonance imaging (MRI) protocols, including to help distinguish HCM patients with regionally impaired cardiac function.

METHODS

Forty-eight HCM patients, five patients with "septal knuckle" (SK), and 20 healthy volunteers underwent MRI at 1.5T; a tagged 3Ch cine was added to the protocol. Regional strain, myocardial wall thickness, and mitral valve leaflet lengths were measured in the 3Ch view.

RESULTS

In HCM, we found a reduced tangential strain with decreased diastolic relaxation in both hypertrophied (p = 0.003) and remote segments (p = 0.035). Strain in the basal septum correlated with the length of the coaptation zone + residual leaflet (r = 0.48, p < 0.001). In the basal free wall, patients with SK had faster relaxation compared to HCM patients with septal hypertrophy.

DISCUSSION

The 3Ch tagged MRI sequence provides useful information for the examination of suspected HCM patients, with minimal additional time cost. Local wall function is closely associated with morphological changes of the mitral apparatus measured in the same plane and may provide insights into mechanisms of obstruction. The additional strain information may be helpful when analyzing local myocardial wall motion patterns in the presence of SK.

Impact of cardiac magnetic resonance on the diagnosis of hypertrophic cardiomyopathy - a 10-year experience with over 1000 patients

Objectives

To assess the value of cardiac MRI in comparison to echocardiography in consecutive patients with previously diagnosed and new suspected hypertrophic cardiomyopathy (HCM).

Methods

All MRI studies of patients with HCM or suspected disease performed at our centre within a 10-year time period were evaluated. Initial diagnoses (echocardiography-based) and final (MRI-based) diagnoses were compared in subgroups, and the discrepancies were recorded.

Results

A total of 1006 subjects with HCM or suspected HCM were identified (61% males, 39% females; median age, 49.1 years; interquartile range, 34.9–60.4). In 12 (2.2%) out of 550 patients with known HCM, MRI indicated a diagnosis other than HCM, including but not limited to the subaortic membrane (n = 1, 8.3%) or mild left ventricular hypertrophy (n = 5, 41.7%). Among all patients with suspected HCM (n = 456), MRI diagnosis was different from HCM in 5.3% (n = 24) of patients. In an additional 20.4% of patients (n = 93), no significant hypertrophy was present. In total, among patients with suspected HCM, MRI led to clear HCM diagnosis in 204 (44.7%) patients. Among patients with a history of uncontrolled hypertension suspected of having HCM, MRI aided in identifying cardiomyopathy in 47.9% of patients. This subgroup contained the largest proportion of patients with an ambiguous diagnosis, namely, 29.6% compared with 13.8% in the remaining groups of patients with suspected HCM (p = 0.0001).

Conclusions

In a small but important group of patients with ultrasound-based HCM, cardiac MRI can diagnose previously unknown conditions and/or refute suspected cardiomyopathy. The diagnostic yield of MRI when compared to echocardiography in patients suspected of having HCM is 44.7%.

Key Points

• Out of 550 patients previously diagnosed with echocardiography but without magnetic resonance imaging (MRI) as having hypertrophic cardiomyopathy (HCM), we diagnosed a different disease in 12 (2.2%) patients using MRI.

• Among patients with suspected HCM based on echocardiography, MRI led to clear HCM diagnosis in 44.7% of patients.

• In patients with a history of uncontrolled hypertension suspected, based on an echocardiogram, of having HCM, MRI aided in identifying cardiomyopathy in 47.9% of patients. This subgroup contained the largest proportion of patients with an ambiguous diagnosis.

Automated quantification of myocardial tissue characteristics from native T1 mapping using neural networks with uncertainty-based quality-control

BACKGROUND

Tissue characterisation with cardiovascular magnetic resonance (CMR) parametric mapping has the potential to detect and quantify both focal and diffuse alterations in myocardial structure not assessable by late gadolinium enhancement. Native T1 mapping in particular has shown promise as a useful biomarker to support diagnostic, therapeutic and prognostic decision-making in ischaemic and non-ischaemic cardiomyopathies.

METHODS

Convolutional neural networks (CNNs) with Bayesian inference are a category of artificial neural networks which model the uncertainty of the network output. This study presents an automated framework for tissue characterisation from native shortened modified Look-Locker inversion recovery ShMOLLI T1 mapping at 1.5 T using a Probabilistic Hierarchical Segmentation (PHiSeg) network (PHCUMIS 119-127, 2019). In addition, we use the uncertainty information provided by the PHiSeg network in a novel automated quality control (QC) step to identify uncertain T1 values. The PHiSeg network and QC were validated against manual analysis on a cohort of the UK Biobank containing healthy subjects and chronic cardiomyopathy patients (N=100 for the PHiSeg network and N=700 for the QC). We used the proposed method to obtain reference T1 ranges for the left ventricular (LV) myocardium in healthy subjects as well as common clinical cardiac conditions.

RESULTS

T1 values computed from automatic and manual segmentations were highly correlated (r=0.97). Bland-Altman analysis showed good agreement between the automated and manual measurements. The average Dice metric was 0.84 for the LV myocardium. The sensitivity of detection of erroneous outputs was 91%. Finally, T1 values were automatically derived from 11,882 CMR exams from the UK Biobank. For the healthy cohort, the mean (SD) corrected T1 values were 926.61 (45.26), 934.39 (43.25) and 927.56 (50.36) for global, interventricular septum and free-wall respectively.

CONCLUSIONS

The proposed pipeline allows for automatic analysis of myocardial native T1 mapping and includes a QC process to detect potentially erroneous results. T1 reference values were presented for healthy subjects and common clinical cardiac conditions from the largest cohort to date using T1-mapping images.

Comparison of tissue tracking assessment by cardiovascular magnetic resonance for cardiac amyloidosis and hypertrophic cardiomyopathy

BACKGROUND

Administration of gadolinium-contrast can cause problems in cardiac amyloidosis (CA) patients with impaired renal function.

PURPOSE

To compare patterns of cardiovascular magnetic resonance tissue tracking (CMR-TT) for CA and hypertrophic cardiomyopathy (HCM) and to assess the feasibility of CMR-TT to distinguish between these diseases without administration of gadolinium-contrast.

MATERIAL AND METHODS

Included were 54 patients with biopsy-proven CA, 40 patients with HCM, and 30 healthy people. We calculated strain ratio of apex to base (SRAB) in the left ventricle (LV) using radial (R), circumferential (C), and longitudinal (L) strain from CMR-TT. The LV ejection fraction (LVEF) and the ratio of septal to posterior wall at basal level were also calculated. Late gadolinium enhancement (LGE) image analysis was performed for differential diagnosis. Area under the receiver operating characteristic curve (AUC) comparisons were used.

RESULTS

All SRAB values were significantly different between CA and HCM (all P < 0.001). AUC values for parameters were 0.806 for LVEF, 0.815 for ratio of wall thickness, 0.944 for the LGE pattern, 0.898 for SRAB_R, 0.880 for SRAB_C, and 0.805 for SRAB_L. AUCs for the LGE pattern were significantly higher than for LVEF, ratio of wall thickness and SRAB_L (all P < 0.008). No significant differences were seen between AUCs for the LGE pattern, SRAB_R, and SRAB_C (all P > 0.109).

CONCLUSION

SRAB_R and SRAB_C were reliable parameters for distinguishing between CA and HCM.

Prevalence and clinical significance of cardiovascular magnetic resonance adenosine stress-induced myocardial perfusion defect in hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is thought to be associated with microvascular dysfunction. Adenosine stress-perfusion cardiovascular magnetic resonance imaging (CMR) is a sensitive method for assessing microvascular perfusion abnormalities. We evaluated the prevalence and clinical characteristics of HCM patients with adenosine-induced perfusion defects on CMR.

METHODS

Among 189 consecutive patients with HCM who underwent adenosine-stress perfusion CMR, 115 patients who had clinical, echocardiography, 24-h Holter monitoring and treadmill exercise test data were analyzed. We calculated myocardial perfusion ratio index from the intensity-over-time curve to quantify perfusion defects. The presence and extent of the stress-induced perfusion defect were compared with clinical characteristics, presence and extent of late gadolinium enhancement (LGE), left ventricular (LV) mass index and volume, presence of non-sustained ventricular tachycardia (NSVT) and results of treadmill exercise test.

RESULTS

The mean age of enrolled patients was 51.8 ± 11.3 years. Most patients were asymptomatic except 25 subjects presented with New York Heart Association Class II dyspnea and 16 patients with atypical non-exertional chest discomfort. LGE was present in 103 (89.6%) subjects. Adenosine stress-induced perfusion defects were present in 48 (42%) subjects. None of the perfusion defects corresponded with a single or multiple coronary artery territories, showing a multiple patchy pattern in 24 (50.0%), a concentric subendocardial pattern in 20 subjects (41.7%), and as a single blot-like defect in the remaining 4 (8.3%). A perfusion defect was associated with NSVT, LV apical aneurysm, higher LV mass index, and higher LGE volume on univariate analysis. Multivariate analysis revealed female gender (P = 0.008), presence of apical aneurysm and NSVT (P = 0.036 and 0.047, respectively), and LV mass index (P = 0.022) to be independently associated with adenosine stress-induced perfusion defects.

CONCLUSIONS

In patients with HCM, adenosine-stress perfusion defects on CMR are present in more than 40% of subjects. This perfusion defect is associated with NSVT, higher LV mass index, and apical aneurysms. The prognostic value of this finding needs further elucidation.

Comprehensive Assessment of Endomyocardial Fibrosis with Cardiac MRI: Morphology, Function, and Tissue Characterization

Endomyocardial fibrosis (EMF) affects approximately 12 million persons worldwide and is an important cause of restrictive cardiomyopathy in the developing world, with the highest prevalence reported in sub-Saharan Africa, South Asia, and South America. EMF is characterized by apical filling with fibrotic tissue of one or both ventricles, often associated with thrombus, calcification, and atrioventricular valve regurgitation, leading to typical symptoms of restrictive heart failure. Transthoracic echocardiography (TTE) is the first-line modality for assessment of EMF, basically owing to its widespread availability. However, in recent years cardiac MRI has emerged as a powerful tool for assessment of cardiac morphology and function, with higher accuracy than TTE, along with the unique advantage of being able to provide comprehensive noninvasive tissue characterization. Delayed enhancement (DE) imaging is the cornerstone of cardiac MRI tissue characterization and allows accurate identification of myocardial fibrosis, conveying valuable additional diagnostic and prognostic information. The typical DE pattern in EMF, described as the "double V" sign, consists of a three-layered pattern of normal myocardium, thickened enhanced endomyocardium, and overlying thrombus at the apex of the affected ventricle; it has excellent correlation with histopathologic findings and plays an important role in differentiating EMF from other cardiomyopathies. Conversely, fibrous tissue deposition quantified using DE imaging, when indexed to body surface area, has been shown to be a strong independent predictor of mortality. The aim of this review is to summarize state-of-the-art applications of cardiac MRI for diagnostic and prognostic assessment of patients with suspected or confirmed EMF. Online supplemental material is available for this article. ^©RSNA, 2020.

Three-dimensional Deep Convolutional Neural Networks for Automated Myocardial Scar Quantification in Hypertrophic Cardiomyopathy: A Multicenter Multivendor Study

Background Cardiac MRI late gadolinium enhancement (LGE) scar volume is an important marker for outcome prediction in patients with hypertrophic cardiomyopathy (HCM); however, its clinical application is hindered by a lack of measurement standardization. Purpose To develop and evaluate a three-dimensional (3D) convolutional neural network (CNN)-based method for automated LGE scar quantification in patients with HCM. Materials and Methods We retrospectively identified LGE MRI data in a multicenter (n = 7) and multivendor (n = 3) HCM study obtained between November 2001 and November 2011. A deep 3D CNN based on U-Net architecture was used for LGE scar quantification. Independent CNN training and testing data sets were maintained with a 4:1 ratio. Stacks of short-axis MRI slices were split into overlapping substacks that were segmented and then merged into one volume. The 3D CNN per-site and per-vendor performances were evaluated with respect to manual scar quantification performed in a core laboratory setting using Dice similarity coefficient (DSC), Pearson correlation, and Bland-Altman analyses. Furthermore, the performance of 3D CNN was compared with that of two-dimensional (2D) CNN. Results This study included 1073 patients with HCM (733 men; mean age, 49 years ± 17 [standard deviation]). The 3D CNN-based quantification was fast (0.15 second per image) and demonstrated excellent correlation with manual scar volume quantification (r = 0.88, P < .001) and ratio of scar volume to total left ventricle myocardial volume (%LGE) (r = 0.91, P < .001). The 3D CNN-based quantification strongly correlated with manual quantification of scar volume (r = 0.82-0.99, P < .001) and %LGE (r = 0.90-0.97, P < .001) for all sites and vendors. The 3D CNN identified patients with a large scar burden (>15%) with 98% accuracy (202 of 207) (95% confidence interval [CI]: 95%, 99%). When compared with 3D CNN, 2D CNN underestimated scar volume (r = 0.85, P < .001) and %LGE (r = 0.83, P < .001). The DSC of 3D CNN segmentation was comparable among different vendors (P = .07) and higher than that of 2D CNN (DSC, 0.54 ± 0.26 vs 0.48 ± 0.29; P = .02). Conclusion In the hypertrophic cardiomyopathy population, a three-dimensional convolutional neural network enables fast and accurate quantification of myocardial scar volume, outperforms a two-dimensional convolutional neural network, and demonstrates comparable performance across different vendors. © RSNA, 2019 Online supplemental material is available for this article.

MRI native T1 and T2 mapping of myocardial segments in hypertrophic cardiomyopathy: tissue remodeling manifested prior to structure changes

OBJECTIVE

The aim of this study was to examine the local myocardial segments in hypertrophic cardiomyopathy (HCM) by MRI T1 and T2 mapping, and to investigate how tissue remodeling correlates with structural and functional remodeling in HCM.

METHODS

47 patients with HCM and 19 healthy volunteers were enrolled in this study. All subjects underwent cardiac MRI at 3.0 T. Native T1 and T2 values, end-diastolic wall thickness (EDTH), and percentage of systolic wall thickening (PSWT) were assessed in the left ventricular segments according to the American Heart Association model. Myocardial segments were categorized as normal, non-hypertrophic, mild-hypertrophic, moderate-hypertrophic, and severe-hypertrophic based on EDTH. The difference among all five groups, and the correlation between native T1 and T2 values, EDTH, and PSWT were evaluated.

RESULTS

Native T1 and T2 values were significantly elevated in both non-hypertrophic and hypertrophic segments of HCM patients compared to controls (both p < 0.001). PSWT was preserved in non-hypertrophic segments (p = 0.838), while significantly impaired (p < 0.001) in hypertrophic segments. Native T1 value of severe hypertrophic segments in HCM was significantly higher than segments of mild and moderate hypertrophy (p < 0.05).

CONCLUSION

In HCM patients, the non-hypertrophic myocardial segments already demonstrated significantly elevated T1 and T2 values, despite normal wall thickness and preserved contraction function. The finding suggests that tissue remodeling may precede morphological and functional remodeling in HCM. MRI native T1 and T2 mapping can provide additional value for HCM diagnosis at an early stage.

ADVANCES IN KNOWLEDGE

Myocardial tissue remodeling, as detected by MRI native T1 and T2 mapping, occurs earlier than morphological and functional changes in HCM patients.

Extracellular Matrix From Hypertrophic Myocardium Provokes Impaired Twitch Dynamics in Healthy Cardiomyocytes

•

The goal of this study was to examine the effects of diseased extracellular matrix on the behavior of healthy heart cells.

•

Myocardium was harvested from a genetically engineered miniature pig carrying the hypertrophic cardiomyopathy mutation MYH7 R403Q and from a wild-type littermate.

•

Engineered heart tissues were created by seeding healthy human induced pluripotent stem cell–derived cardiomyocytes onto thin strips of decellularized porcine myocardium.

•

Engineered heart tissues made from the extracellular matrix of hypertrophic cardiomyopathy hearts exhibit increased stiffness, impaired relaxation, and increased force development.

•

This suggests that diseased extracellular matrix can provoke abnormal contractile behavior in otherwise healthy cardiomyocytes.

Hypertrophic cardiomyopathy (HCM) is often caused by single sarcomeric gene mutations that affect muscle contraction. Pharmacological correction of mutation effects prevents but does not reverse disease in mouse models. Suspecting that diseased extracellular matrix is to blame, we obtained myocardium from a miniature swine model of HCM, decellularized thin slices of the tissue, and re-seeded them with healthy human induced pluripotent stem cell–derived cardiomyocytes. Compared with cardiomyocytes grown on healthy extracellular matrix, those grown on the diseased matrix exhibited prolonged contractions and poor relaxation. This outcome suggests that extracellular matrix abnormalities must be addressed in therapies targeting established HCM.

Sex Differences at the Time of Myectomy in Hypertrophic Cardiomyopathy

BACKGROUND

One of the first clinically detectable alterations in heart function in hypertrophic cardiomyopathy (HCM) is a decline in diastolic function. Diastolic dysfunction is caused by changes in intrinsic properties of cardiomyocytes or an increase in fibrosis. We investigated whether clinical and cellular parameters of diastolic function are different between male and female patients with HCM at the time of myectomy.

METHODS AND RESULTS

Cardiac tissue from the interventricular septum of patients with HCM (27 women and 44 men) was obtained during myectomy preceded by echocardiography. At myectomy, female patients were 7 years older than male patients and showed more advanced diastolic dysfunction than men evident from significantly higher values for E/e' ratio, left ventricular filling pattern, tricuspid regurgitation velocity, and left atrial diameter indexed for body surface. Whereas most male patients (56%) showed mild (grade I) diastolic dysfunction, 50% of female patients showed grade III diastolic dysfunction. Passive tension in HCM cardiomyocytes was comparable with controls, and myofilament calcium sensitivity was higher in HCM compared with controls, but no sex differences were observed in myofilament function. In female patients with HCM, titin was more compliant, and more fibrosis was present compared with men. Differences between female and male patients with HCM remained significant after correction for age.

CONCLUSIONS

Female patients with HCM are older at the time of myectomy and show greater impairment of diastolic function. Furthermore, left ventricular and left atrial remodeling is increased in women when corrected for body surface area. At a cellular level, HCM women showed increased compliant titin and a larger degree of interstitial fibrosis.

Left Ventricular Strain Is Abnormal in Preclinical and Overt Hypertrophic Cardiomyopathy: Cardiac MR Feature Tracking

Purpose To evaluate myocardial strain and circumferential transmural strain difference (cTSD; the difference between epicardial and endocardial circumferential strain) in a genotyped cohort with hypertrophic cardiomyopathy (HCM) and to explore correlations between cTSD and other anatomic and functional markers of disease status. Left ventricular (LV) dysfunction may indicate early disease in preclinical HCM (sarcomere mutation carriers without LV hypertrophy). Cardiac MRI feature tracking may be used to evaluate myocardial strain in carriers of HCM sarcomere mutation. Materials and Methods Participants with HCM and their family members participated in a prospective, multicenter, observational study (HCMNet). Genetic testing was performed in all participants. Study participants underwent cardiac MRI with temporal resolution at 40 msec or less. LV myocardial strain was analyzed by using feature-tracking software. Circumferential strain was measured at the epicardial and endocardial surfaces; their difference yielded the circumferential transmural strain difference (cTSD). Multivariable analysis to predict HCM status was performed by using multinomial logistic regression adjusting for age, sex, and LV parameters. Results Ninety-nine participants were evaluated (23 control participants, 34 participants with preclinical HCM [positive for sarcomere mutation and negative for LV hypertrophy], and 42 participants with overt HCM [positive for sarcomere mutation and negative for LV hypertrophy]). The average age was 25 years ± 11 and 44 participants (44%) were women. Maximal LV wall thickness was 9.5 mm ± 1.4, 9.8 mm ± 2.2, and 16.1 mm ± 5.3 in control participants, participants with preclinical HCM (P = .496 vs control participants), and participants with overt HCM (P < .001 vs control participants), respectively. cTSD for control participants, preclinical HCM, and overt HCM was 14% ± 4, 17% ± 4, and 22% ± 7, respectively (P < .01 for all comparisons). In multivariable models (controlling for septal thickness and log-transformed N-terminal brain-type natriuretic peptide), cTSD was predictive of preclinical and overt HCM disease status (P < .01). Conclusion Cardiac MRI feature tracking identifies myocardial dysfunction not only in participants with overt hypertrophic cardiomyopathy, but also in carriers of sarcomere mutation without left ventricular hypertrophy, suggesting that contractile abnormalities are present even when left ventricular wall thickness is normal. © RSNA, 2018 Online supplemental material is available for this article.

The association between T wave inversion and apical hypertrophic cardiomyopathy

Objectives Electrocardiograhy (ECG) is the first step in hypertrophic cardiomyopathy (HCMP) diagnosis. For various reasons, the T wave inversion (TWI) and ECG change with time and HCMP is not easy to diagnosis. The aim of this retrospective study was to investigate the association between TWI on ECG and apical HCMP. Methods A total of 4,730 ECGs presenting TWI from January 2011 to March 2013 in Pusan National University Hospital were enrolled. 133 patients who were examined by both echocardiography and coronary angiogram were analyzed. Patients were divided into two groups: Group A (TWI ≥ 10 mm) and Group B (5 mm ≤ TWI &lt; 10 mm). HCMP is defined by a wall thickness ≥ 15mm in one or more LV myocardial segments. Apical HCMP is defined to be hypertrophy that is confined to LV apex. The patients who had ECGs with at least one month interval were divided 3 groups: Normal T wave, Abnormal T wave, and Persistent TWI. The prevalence of Apical HCMP and coronary artery disease (CAD) was reviewed among the three groups. Results In this study there were a total 133 patients, with patients divided into Group A which had 15 patients and Group B which had 118 patients. Among the 23 patients with apical HCMP, three patients were Group A and twenty patients were Group B ( P = 0.769). Regarding constancy of TWI, persistent TWI group was higher in apical HCMP than in other groups ( P = 0.038). CAD had no difference between groups ( P = 0.889). Conclusions T wave negativity was not associated with incidence of apical HCMP. However, apical HCMP was diagnosed more frequently in patients with persistent TWI. Further follow up echocardiographic study is needed to evaluate the progression of apical HCMP in patients with TWI.

Early Imaging Biomarker of Myocardial Glucose Adaptations in High-Fat-Diet-Induced Insulin Resistance Model by Using 18F-FDG PET and [U-13C]glucose Nuclear Magnetic Resonance Tracer

Background

High-fat diet (HFD) induces systemic insulin resistance leading to myocardial dysfunction. We aim to characterize the early adaptations of myocardial glucose utility to HFD-induced insulin resistance.

Methods

Male Sprague–Dawley rats were assigned into two groups, fed a regular chow diet or HFD ad libitum for 10 weeks. We used in vivo imaging of cardiac magnetic resonance (CMR), ¹⁸F-FDG PET, and ex vivo nuclear magnetic resonance (NMR) metabolomic analysis for the carbon-13-labeled glucose ([U-¹³C]Glc) perfused myocardium.

Results

As compared with controls, HFD rats had a higher ejection fraction and a smaller left ventricular end-systolic volume (P < 0.05), with SUV_max of myocardium on ¹⁸F-FDG PET significantly increased in 4 weeks (P < 0.005). The [U-¹³C]Glc probed the increased glucose uptake being metabolized into pyruvate and acetyl-CoA, undergoing oxidative phosphorylation via the tricarboxylic acid (TCA) cycle, and then synthesized into glutamic acid and glutamine, associated with overexpressed LC3B (P < 0.05).

Conclusions

HFD-induced IR associated with increased glucose utility undergoing oxidative phosphorylation via the TCA cycle in the myocardium is supported by overexpression of glucose transporter, acetyl-CoA synthase. Noninvasive imaging biomarker has potentials in detecting the metabolic perturbations prior to the decline of the left ventricular function.

Myocardial stress perfusion magnetic resonance in children with hypertrophic cardiomyopathy

BACKGROUND

Microvascular dysfunction in hypertrophic cardiomyopathy has been associated with poor clinical outcome. Several studies have demonstrated a reduced perfusion reserve proportional to the magnitude of the hypertrophy. We investigated the utility of stress perfusion cardiac MRI to detect microvascular dysfunction in children with hypertrophic cardiomyopathy.

METHODS

From January 2016 to January 2017, 13 patients, with a mean age of 15.3 years, with hypertrophic cardiomyopathy underwent regadenoson stress perfusion cardiac MRI (1.5-T Siemens Aera). A single-shot, T1-weighted saturation recovery gradient echo was used for first-pass perfusion in a multiple-slices group, including three short-axis slices and one four-chamber slice. Coronary vasodilatory stress was achieved using bolus injection of regadenoson (lexiscan 0.4 mg/5 ml) and dynamic perfusion during rest and stress performed by administering 0.05 mmol/kg of gadolinium contrast agent (gadoteridol) injected at a rate of 3.5 ml/s, followed by assessment of viability using two-dimensional phase-sensitive inversion recovery of the entire myocardium.

RESULTS

All patients completed protocols with no interruptions. In all, seven patients developed perfusion defects after the administration of regadenoson. Asymmetric septal hypertrophy was the most common pattern of hypertrophic cardiomyopathy (n=4) in those with abnormal perfusion. A total of four patients with perfusion defects had a maximum wall thickness <30 mm. The finding of perfusion defects in areas without late gadolinium enhancement in some of our patients indicates that gadolinium enhancement by itself could underestimate the true extension of microvascular disease. Out of seven patients, five patients with positive stress cardiac MRI have undergone implantable cardioverter defibrillator placement based on current guidelines.

CONCLUSIONS

Regadenoson stress cardiac MRI is feasible and clinically valuable in paediatric patients. It is particularly effective in unmasking abnormal myocardial perfusion in the presence of microvascular dysfunction in children with hypertrophic cardiomyopathy.

Left Ventricular Wall Stress Is Sensitive Marker of Hypertrophic Cardiomyopathy With Preserved Ejection Fraction

Hypertrophic cardiomyopathy (HCM) patients present altered myocardial mechanics due to the hypertrophied ventricular wall and are typically diagnosed by the increase in myocardium wall thickness. This study aimed to quantify regional left ventricular (LV) shape, wall stress and deformation from cardiac magnetic resonance (MR) images in HCM patients and controls, in order to establish superior measures to differentiate HCM from controls. A total of 19 HCM patients and 19 controls underwent cardiac MR scans. The acquired MR images were used to reconstruct 3D LV geometrical models and compute the regional parameters (i.e., wall thickness, curvedness, wall stress, area strain and ejection fraction) based on the standard 16 segment model using our in-house software. HCM patients were further classified into four quartiles based on wall thickness at end diastole (ED) to assess the impact of wall thickness on these regional parameters. There was a significant difference between the HCM patients and controls for all regional parameters (P < 0.001). Wall thickness was greater in HCM patients at the end-diastolic and end-systolic phases, and thickness was most pronounced in segments at the septal regions. A multivariate stepwise selection algorithm identified wall stress index at ED (σ_i,ED) as the single best independent predictor of HCM (AUC = 0.947). At the cutoff value σ_i,ED < 1.64, both sensitivity and specificity were 94.7%. This suggests that the end-diastolic wall stress index incorporating regional wall curvature—an index based on mechanical principle—is a sensitive biomarker for HCM diagnosis with potential utility in diagnostic and therapeutic assessment.