Left Ventricular Mass in Hypertrophic Cardiomyopathy Assessed by 2D-Echocardiography: Validation with Magnetic Resonance Imaging

Echocardiographic Strain Abnormalities Precede Left Ventricular Hypertrophy Development in Hypertrophic Cardiomyopathy Mutation Carriers

Hypertrophic cardiomyopathy (HCM) is a genetic disease characterized by unexplained left ventricular hypertrophy (LVH), diastolic dysfunction, and increased sudden-death risk. Early detection of the phenotypic expression of the disease in genetic carriers without LVH (Gen+/Phen-) is crucial for emerging therapies. This clinical study aims to identify echocardiographic predictors of phenotypic development in Gen+/Phen-. Sixteen Gen+/Phen- (one subject with troponin T, six with myosin heavy chain-7, and nine with myosin-binding protein C3 mutations), represented the study population. At first and last visit we performed comprehensive 2D speckle-tracking strain echocardiography. During a follow-up of 8 ± 5 years, five carriers developed LVH (LVH+). At baseline, these patients were older than those who did not develop LVH (LVH-) (30 ± 8 vs. 15 ± 8 years, p = 0.005). LVH+ had reduced peak global strain rate during the isovolumic relaxation period (SRIVR) (0.28 ± 0.05 vs. 0.40 ± 0.11 1/s, p = 0.048) and lower global longitudinal strain (GLS) (-19.8 ± 0.4 vs. -22.3 ± 1.1%; p < 0.0001) than LVH- at baseline. SRIVR and GLS were not correlated with age (overall, p > 0.08). This is the first HCM study investigating subjects before they manifest clinically significant or relevant disease burden or symptomatology, comparing at baseline HCM Gen+/Phen- subjects who will develop LVH with those who will not. Furthermore, we identified highly sensitive, easily obtainable, age- and load-independent echocardiographic predictors of phenotype development in HCM gene carriers who may undergo early preventive treatment.

Automatic left ventricle volume and mass quantification from 2D cine-MRI: Investigating papillary muscle influence

OBJECTIVE

Early detection of cardiovascular diseases is based on accurate quantification of the left ventricle (LV) function parameters. In this paper, we propose a fully automatic framework for LV volume and mass quantification from 2D-cine MR images already segmented using U-Net.

METHODS

The general framework consists of three main steps: Data preparation including automatic LV localization using a convolution neural network (CNN) and application of morphological operations to exclude papillary muscles from the LV cavity. The second step consists in automatically extracting the LV contours using U-Net architecture. Finally, by integrating temporal information which is manifested by a spatial motion of myocytes as a third dimension, we calculated LV volume, LV ejection fraction (LVEF) and left ventricle mass (LVM). Based on these parameters, we detected and quantified cardiac contraction abnormalities using Python software.

RESULTS

CNN was trained with 35 patients and tested on 15 patients from the ACDC database with an accuracy of 99,15 %. U-Net architecture was trained using ACDC database and evaluated using local dataset with a Dice similarity coefficient (DSC) of 99,78 % and a Hausdorff Distance (HD) of 4.468 mm (p < 0,001). Quantification results showed a strong correlation with physiological measures with a Pearson correlation coefficient (PCC) of 0,991 for LV volume, 0.962 for LVEF, 0.98 for stroke volume (SV) and 0.923 for LVM after pillars' elimination. Clinically, our method allows regional and accurate identification of pathological myocardial segments and can serve as a diagnostic aid tool of cardiac contraction abnormalities.

CONCLUSION

Experimental results prove the usefulness of the proposed method for LV volume and function quantification and verify its potential clinical applicability.

Mechano-energetic efficiency in patients with hypertrophic cardiomyopathy with and without sarcomeric mutations

Hypertrophic cardiomyopathy (HCM) is mainly caused by sarcomeric mutations which may affect myocardial mechano-energetic efficiency (MEE). We investigated the effects of sarcomeric mutations on MEE. A non-invasive pressure/volume (P/V) analysis was performed. We included 49 genetically screened HCM patients. MEEi was calculated as the ratio between stroke volume and heart rate normalized by LV mass. Fifty-seven percent (57%) HCM patients carried a sarcomeric mutation. Patients with and without sarcomeric mutations had similar LV ejection fraction, heart rate, LV mass, and LV outflow gradient. Younger age at diagnosis, family history of HCM, and lower MEEi were associated with presence of sarcomeric mutation (p = 0.017; p = 0.001 and p = 0.0001, respectively). Lower MEEi in HCM with sarcomeric mutation is not related to significant differences on filling pressure as shown on P/V analysis. Sarcomeric mutations determine a reduction of the LV pump performance as estimated by MEEi in HCM. Lower MEEi may predict a positive genetic analysis.

Comparison of echocardiographic methods for calculating left ventricular mass in elite rugby football league athletes and the impact on chamber geometry

Background

Recommendations for the echocardiographic assessment of left ventricular (LV) mass in the athlete suggest the use of the linear method using a two-tiered classification system (2TC). The aims of this study were to compare the linear method and the area-length (A-L) method for LV mass in elite rugby football league (RFL) athletes and to establish how any differences impact the classification of LV geometry using 2TC and four-tier (4TC) classification systems.

Methods

Two hundred and twenty (220) male RFL athletes aged 25 ± 5 (14-34 years) were recruited. All athletes underwent echocardiography and LV mass was calculated by the American Society of Echocardiography (ASE) corrected Linear equation (2D) and the A-L method. Left ventricular mass Index (LVMi) was used with relative wall thickness to determine geometry in the 2TC and with concentricity and LV end diastolic volume index for the 4TC. Method specific recommended cut-offs were utilised.

Results

Higher values of absolute (197 ± 34 vs. 181 ± 34 g; p < 0.0001) and indexed (92 ± 13 vs. 85 ± 13 g/m2; p < 0.0001) measures of LV mass were obtained from A-L compared to the linear method. Normal LV geometry was demonstrated in 98.2% and 80% of athletes whilst eccentric hypertrophy in 1.4% and 19.5% for linear and A-L respectively. Both methods provided 0.5% as having concentric remodelling and 0% as having concentric hypertrophy. Allocation to the 4TC resulted in 97% and 80% with normal geometry, 0% and 8.6% with eccentric dilated hypertrophy, 0% and 7.7% with eccentric non-dilated hypertrophy, 1.4% and 0.5% with concentric remodelling and 1.4% and 3% with concentric non-dilated hypertrophy for linear and A-L methods respectively. No participants had concentric dilated hypertrophy from either methods.

Conclusion

The linear and A-L method for calculation of LV mass in RFL athletes are not interchangeable with significantly higher values obtained using A-L method impacting on geometry classification. More athletes present with eccentric hypertrophy using 2TC and eccentric dilated/non-dilated using 4TC. Further studies should be aimed at establishing the association of A-L methods of LV mass and application of the 4TC to the multi-factorial demographics of the athlete.

Accuracy of Devereaux and Teichholz formulas for left ventricular mass calculation in different geometric patterns: comparison with cardiac magnetic resonance imaging

Left ventricular (LV) myocardial mass is important in the evaluation of cardiac remodeling and requires accurate assessment when performed on linear measurements in two-dimensional echocardiography (Echo). We aimed to compare the accuracy of the Devereaux formula (DEV) and the Teichholz formula (TEICH) in calculating LV myocardial mass in Echo using cardiac magnetic resonance (CMR) as the reference method. Based on preceding mathematical calculations, we identified primarily LV size rather than wall thickness as the main source of bias between DEV and TEICH in a retrospective derivation cohort (n = 1276). Although LV mass from DEV and TEICH were correlated with CMR, TEICH did not show a proportional bias as did DEV (- 2 g/m2 vs. + 22 g/m2). This could be validated in an independent prospective cohort (n = 226) with symptomatic non-ischemic heart failure. DEV systematically overestimated LV mass in all tiers of LV remodeling as compared to TEICH. In conclusion, the TEICH method accounts for the changes in LV geometry with increasing LV mass and thus better reflects the different pattern of LV remodeling than the DEV method. This has important clinical implications, as TEICH may be more appropriate for use in clinical practice, rather than DEV, currently recommended.

Genetic Determinants of the Interventricular Septum Are Linked to Ventricular Septal Defects and Hypertrophic Cardiomyopathy

BACKGROUND

A large proportion of genetic risk remains unexplained for structural heart disease involving the interventricular septum (IVS) including hypertrophic cardiomyopathy and ventricular septal defects. This study sought to develop a reproducible proxy of IVS structure from standard medical imaging, discover novel genetic determinants of IVS structure, and relate these loci to diseases of the IVS, hypertrophic cardiomyopathy, and ventricular septal defect.

METHODS

We estimated the cross-sectional area of the IVS from the 4-chamber view of cardiac magnetic resonance imaging in 32 219 individuals from the UK Biobank which was used as the basis of genome wide association studies and Mendelian randomization.

RESULTS

Measures of IVS cross-sectional area at diastole were a strong proxy for the 3-dimensional volume of the IVS (Pearson r=0.814, P=0.004), and correlated with anthropometric measures, blood pressure, and diagnostic codes related to cardiovascular physiology. Seven loci with clear genomic consequence and relevance to cardiovascular biology were uncovered by genome wide association studies, most notably a single nucleotide polymorphism in an intron of CDKN1A (rs2376620; β, 7.7 mm2 [95% CI, 5.8-11.0]; P=6.0×10-10), and a common inversion incorporating KANSL1 predicted to disrupt local chromatin structure (β, 8.4 mm2 [95% CI, 6.3-10.9]; P=4.2×10-14). Mendelian randomization suggested that inheritance of larger IVS cross-sectional area at diastole was strongly associated with hypertrophic cardiomyopathy risk (pIVW=4.6×10-10) while inheritance of smaller IVS cross-sectional area at diastole was associated with risk for ventricular septal defect (pIVW=0.007).

CONCLUSIONS

Automated estimates of cross-sectional area of the IVS supports discovery of novel loci related to cardiac development and Mendelian disease. Inheritance of genetic liability for either small or large IVS, appears to confer risk for ventricular septal defect or hypertrophic cardiomyopathy, respectively. These data suggest that a proportion of risk for structural and congenital heart disease can be localized to the common genetic determinants of size and shape of cardiovascular anatomy.

Comparison between pre- and post-contrast cardiac MRI cine images: the impact on ventricular volume and strain measurement

To explore whether contrast agent administration will affect ventricular volume and strain parameters measured on cardiac magnetic resonance cine images. This prospective study enrolled 88 patients, including 32 patients with cardiac amyloidosis (CA), 32 patients with hypertrophic cardiomyopathy (HCM), and 24 control participants, to perform steady-state free precession (SSFP)-cine imaging twice, respectively before and after contrast agent injection. Indexed left and right ventricular (LV and RV) volume and LV strain parameters (peak radial strain [PRS], peak circumferential strain [PCS], peak longitudinal strain [PLS]) were analyzed and compared between the pre- and post-contrast cine groups. Compared to the group of pre-contrast cine, the end-diastolic volume index (EDVi) and end-systolic volume index (ESVi) significantly increased in the group using post-contrast cine images (all p < 0.05), especially in the right ventricle. After contrast injection, the right ventricular ejection fraction (RVEF) decreased significantly (p < 0.05), while the left ventricular ejection fraction (LVEF) only reduced for patients with HCM (p < 0.05). The PRS (37.1 ± 15.2 vs. 32.0 ± 15.4, p < 0.001) and PCS (- 14.9 ± 4.3 vs. - 14.0 ± 4.1, p < 0.001) derived from post-contrast cine images reduced significantly in all patients and this tendency remained in subgroup analysis except for PCS in the control group. The administration of a contrast agent may influence the measurements of ventricular volume and strain. Acquiring pre-contrast cine images were suggested for patients who required more accurate right ventricle evaluation or precise strain assessment.

A new method to quantify left ventricular mass by 2D echocardiography

Increased left ventricular mass (LVM) is a strong independent predictor for adverse cardiovascular events, but conventional echocardiographic methods are limited by poor reproducibility and accuracy. We developed a novel method based on adding the mean wall thickness from the parasternal short axis view, to the left ventricular end-diastolic volume acquired using the biplane model of discs. The participants (n = 85) had various left ventricular geometries and were assessed using echocardiography followed immediately by cardiac magnetic resonance, as reference. We compared our novel two-dimensional (2D) method to various conventional one-dimensional (1D) and other 2D methods as well as the three-dimensional (3D) method. Our novel method had better reproducibility in intra-examiner [coefficients of variation (CV) 9% vs. 11–14%] and inter-examiner analysis (CV 9% vs. 10–20%). Accuracy was similar to the 3D method (mean difference ± 95% limits of agreement, CV): Novel: 2 ± 50 g, 15% vs. 3D: 2 ± 51 g, 16%; and better than the “linear” 1D method by Devereux (7 ± 76 g, 23%). Our novel method is simple, has considerable better reproducibility and accuracy than conventional “linear” 1D methods, and similar accuracy as the 3D-method. As the biplane model forms part of the standard echocardiographic protocol, it does not require specific training and provides a supplement to the modern echocardiographic report.

Automated three-dimensional echocardiographic quantification for left ventricular volume and function in patients with hypertrophic cardiomyopathy

BACKGROUND

Accurate, reproducible, noninvasive determination of left ventricular (LV) volumes and ejection fraction (EF) is important for clinical assessment, selection of therapy, and serial monitoring of patients with hypertrophic cardiomyopathy (HCM). Current clinical Two-dimensional echocardiography (2DE) may cause inaccurate measurements in patients with HCM because of their asymmetric ventricles and limitations of 2DE technology. Three-dimensional echocardiography (3DE) have demonstrated significantly greater accuracy. However, the time-consuming workflow limits the clinical utility of 3DE.

AIM

We aim to compare the performance of a novel automated 3DE system (HeartModel, Philips Healthcare) with 2DE in a group of patients with HCM. Cardiac magnetic resonance (CMR) was reference standard.

METHODS

Fifty-three patients with HCM were examined by automated 3DE (3DEA), two-dimensional biplane Simpson's method (2DBP), manual 3DE method, and CMR, respectively. For patients with poor automated quantification, manual correction was performed. The Pearson correlation coefficient and Bland-Altman analysis and paired Student t tests were used to assess inter-technique agreement.

RESULTS

3DEA measurements with contour editing correlate well with CMR and manual 2DE and 3DE measurements (r = .80-.96). The analysis time of 3DEA was shorter than that of 2DBP (3DEA, 141 ± 15s; 2DBP, 174 ± 17 s). Inter-observer variability was reduced significantly with use of 3DEA.

CONCLUSION

Compared with current clinical 2DBP method, the analysis time of automated 3DE was much shorter with the added benefit of enhanced accuracy and reproducibility. Patients with asymmetric chamber may rely more on the timesaving automated 3DE quantification in the future.

Comparing echocardiographic characteristics in genotype positive-phenotype positive hypertrophic cardiomyopathy and hypertensive left ventricular hypertrophy

AIMS

There is little information about hypertrophic cardiomyopathy (HCM) with pathologic genetic mutations and concurrent hypertension (HTN). Hypertensive left ventricular hypertrophy (LVH) does not exclude an underlying genetic aetiology.

METHODS AND RESULTS

This was a single-centre case-control study of 39 adults with pathologic HCM mutations, confirmed by genetic testing, compared to 39 age- and gender-matched patients with hypertensive LVH. The gene-positive HCM cohort was further stratified by the coexisting presence or absence of HTN. Clinical and echocardiographic characteristics were compared. Of 39 gene-positive HCM, 43.6% (17/39) had concurrent HTN. The gene-positive HCM cohort had larger left atrial (LA) area (22.1 cm2 vs. 18.9 cm2, P = 0.002), more diastolic predominant pulmonary vein flow (38.5% vs. 7.7%, P = 0.001), and more moderate diastolic dysfunction (33.3% vs. 12.8%, P = 0.032) when compared with the hypertensive LVH cohort. Greater left ventricular (LV) mass (277.7 g vs. 207.7 g, P = 0.025), increased frequency of severe LVH (58.8% vs. 27.3%, P = 0.047), and more abnormal global longitudinal strain (GLS) (-14.1% vs. -16.9%, P = 0.049) was observed in the gene-positive HCM cohort with concurrent HTN.

CONCLUSION

Gene-positive HCM, compared to hypertensive LVH, is characterized by more advanced diastolic dysfunction and larger LA size. Gene-positive HCM patients with concomitant HTN had greater LV mass, more severe LVH, and more abnormal GLS, suggesting HTN may negatively affect the progression of myocardial dysfunction in genetic HCM. LVH out-of-proportion to pressure burden in HTN patients should raise suspicion of underlying genetic HCM.

Effects of Angiotensin II Receptor Blockers on Ventricular Hypertrophy in Hypertrophic Cardiomyopathy: A Meta-Analysis of Randomized Controlled Trials

PURPOSE

Animal studies have suggested that angiotensin II receptor blockers (ARBs) can attenuate or reverse the progression of hypertrophic cardiomyopathy, while clinical studies yielded conflicting results. We sought to conduct a meta-analysis to investigate the effect of ARBs in patients with hypertrophic cardiomyopathy.

METHODS

PubMed and EMBASE databases were searched through June 2020. Only randomized controlled trials (RCTs) were included, and each study's quality was assessed using the Jadad scale. The primary outcome was left ventricular mass reduction, and the secondary outcome was the change in left ventricular ejection fraction (LVEF). Data were pooled using the random effects model.

RESULTS

A total of 1294 articles were screened. Five RCTs were included in the final analysis, enrolling 209 patients with hypertrophic cardiomyopathy (101 patients were in the ARB arm). ARB treatment was not associated with either significant left ventricular mass reduction (standardized mean difference: - 0.25; 95% CI: - 0.73, 0.22; p = 0.29) or change in LVEF (weighted mean difference: 0.73%; 95% CI: - 1.10%, 2.56%; p = 0.43). Subgroup analysis showed that losartan, one of the most investigated and commonly used ARBs, was also not associated with significant decreases of left ventricular mass (standardized mean difference: - 0.13; 95% CI: - 0.61, 0.36; p = 0.61).

CONCLUSION

This meta-analysis showed that ARB treatment is not associated with reduced left ventricular mass nor remarkable LVEF change among patients with hypertrophic cardiomyopathy. Further studies with a larger number of patients will be required to confirm these findings.

The cardiac conundrum: a systematic review and bibliometric analysis of authorship in cardiac magnetic resonance imaging studies

PURPOSE

We aimed to assess the role of radiologists, cardiologists, and other medical and non-medical figures in cardiac magnetic resonance imaging (MRI) research in the last 34 years, focusing on first and last authorship, number of published studies, and journal impact factors (IF).

METHODS

Articles in the field of cardiac MRI were considered in this systematic review and retrospective bibliometric analysis. For included studies, the first and last authors were categorized as cardiologists, radiologists/nuclear medicine physicians, medical doctors (MD) with specialties in both cardiology and radiology/nuclear medicine, and other MD and non-MD. Differences in the number of papers published overall and by year and institution location for the first and last author category were assessed. Mean IF differences between author categories were also investigated.

RESULTS

A total of 2053 articles were included in the final analysis. For the first authors (n = 2011), 52% were cardiologists, 22% radiologists/nuclear medicine physicians, 16% other MD, 10% other non-MD, and 1% both cardiologists and radiologists/nuclear medicine physicians. Similarly, the last authors (n = 2029) resulted 54% cardiologists, 22% radiologists/nuclear medicine physicians, 15% other MD, 8% other non-MD, and 2% both cardiologists and radiologists/nuclear medicine physicians. No significant differences due to institution location in the first and last authorship proportions were found. Average journal IF was significantly higher for cardiologist first and last authors when compared to that of radiologists/nuclear medicine physicians (both p < 0.0001).

CONCLUSION

Over 50% of studies in the field of cardiac MRI published in the last 34 years are conducted by cardiologists.