Comparison of cardiac magnetic resonance imaging features of isolated left ventricular non-compaction in adults versus dilated cardiomyopathy in adults

Fractal Analysis of Left Ventricular Trabeculae in Patients with End-Stage Renal Disease: A Random Survival Tree Analysis

BACKGROUND

The complexity of left ventricular (LV) trabeculae is related to the prognosis of several cardiovascular diseases.

PURPOSE

To evaluate the prognostic value of LV trabecular complexity in patients with end-stage renal disease (ESRD).

STUDY TYPE

Prospective outcome study.

POPULATION

207 participants on maintenance dialysis, divided into development (160 patients from 2 centers) and external validation (47 patients from a third center) cohorts, and 72 healthy controls.

FIELD STRENGTH

3.0T, steady-state free precession (SSFP) and modified Look-Locker imaging sequences.

ASSESSMENT

All participants had their trabecular complexity quantified by fractal analysis using cine SSFP images. Patients were followed up every 2 weeks until April 2023, or endpoint events happened. Random Forest (RF) and Cox regression models including age, diabetes, LV mass index, mean basal fractal dimension (FD), and left atrial volume index, were developed to predict major adverse cardiac events (MACE). Patients were divided into low- and high-risk groups based on scores derived from the RF model and survival compared.

STATISTICAL TESTS

Receiver operating characteristic curve analysis; Kaplan-Meier survival analysis with log rank tests; Harrel's C-index to assess model performance. A P value <0.05 was considered statistically significant.

RESULTS

Fifty-five patients (26.57%) experienced MACE during a median follow-up time of 21.83 months. An increased mean basal FD (≥1.324) was associated with a significantly higher risk of MACE. The RF model (C-index: 0.81) had significantly better discrimination than the Cox regression model (C-index: 0.74). Participants of the external validation dataset classified into the high-risk group had a hazard of experiencing MACE increased by 12.29 times compared to those in the low-risk group.

DATA CONCLUSION

LV basal FD was an independent predictor for MACE in patients with ESRD. Reliable risk stratification models could be generated based on LV basal FD and other MRI variables using RF analysis.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 2.

Characteristics of the right ventricle in left ventricular noncompaction with reduced ejection fraction in the light of dilated cardiomyopathy

BACKGROUND

Reports of left ventricular noncompaction (LVNC) rarely include descriptions of the right ventricle (RV). This study aimed to describe the characteristics of the RV in LVNC patients with reduced LV function (LVNC-R) compared with patients with dilated cardiomyopathy (DCM) and subjects with LVNC with normal left ventricular ejection fraction (LV-EF) (LVNC-N).

METHODS

Forty-four LVNC-R patients, 44 LVNC-N participants, and 31 DCM patients were included in this retrospective study (LV-EF: LVNC-R: 33.4±10.2%; LVNC-N: 65.0±5.9%; DCM: 34.6±7.9%). Each group was divided into two subgroups by the amount of RV trabeculation.

RESULTS

There was no difference in the RV-EF between the groups, and the RV trabecular mass correlated positively with the RV volume and negatively with the RV-EF in all the groups. All the measured parameters were comparable between the groups with decreased LV function. The hypertrabeculated RV subgroups showed significantly higher RV volumes and lower RV-EF only in the decreased-LV-function groups. The correlation of LV and RV trabeculation was observed only in the LVNC-N group, while LV trabeculation correlated with RV volumes in both noncompacted groups. Both decreased-LV-function groups had worse RV strain values than the LVNC-N group; however, RV strain values correlated with RV trabeculation predominantly in the LVNC-R group.

CONCLUSIONS

The presence and characteristics of RV hypertrabeculation and the correlations between LV trabeculation and RV parameters raise the possibility of RV involvement in noncompaction; moreover, RV strain values might be helpful in the early detection of RV function deterioration.

The Rare Condition of Left Ventricular Non-Compaction and Reverse Remodeling

Left ventricular non-compaction (LVNC) is a rare disease defined by morphological criteria, consisting of a two-layered ventricular wall, a thin compacted epicardial layer, and a thick hyper-trabeculated myocardium layer with deep recesses. Controversies still exist regarding whether it is a distinct cardiomyopathy (CM) or a morphological trait of different conditions. This review analyzes data from the literature regarding diagnosis, treatment, and prognosis in LVNC and the current knowledge regarding reverse remodeling in this form of CM. Furthermore, for clear exemplification, we report a case of a 41-year-old male who presented symptoms of heart failure (HF). LVNC CM was suspected at the time of transthoracic echocardiography and was subsequently confirmed upon cardiac magnetic resonance imaging. A favorable remodeling and clinical outcome were registered after including an angiotensin receptor neprilysin inhibitor in the HF treatment. LVNC remains a heterogenous CM, and although a favorable outcome is not commonly encountered, some patients respond well to therapy.

Fractal Analysis: Prognostic Value of Left Ventricular Trabecular Complexity Cardiovascular MRI in Participants with Hypertrophic Cardiomyopathy

Background The prognostic value of myocardial trabecular complexity in patients with hypertrophic cardiomyopathy (HCM) is unknown. Purpose To explore the prognostic value of myocardial trabecular complexity using fractal analysis in participants with HCM. Materials and Methods The authors prospectively enrolled participants with HCM who underwent 3.0-T cardiovascular MRI from August 2011 to October 2017. The authors also enrolled 100 age- and sex-matched healthy participants to form a comparison group. Trabeculae were quantified with fractal analysis of cine slices to estimate the fractal dimension (FD). Participants with HCM were divided into normal and high FD groups according to the upper limit of normal reference value from the healthy group. The primary end point was defined as all-cause mortality and aborted sudden cardiac death. The secondary end point was the composite of the primary end point and readmission to the hospital owing to heart failure. Internal validation was performed using the bootstrapping method. Results A total of 378 participants with HCM (median age, 50 years; age range, 40-61 years; 207 men) and 100 healthy participants (median age, 46 years; age range, 36-59 years; 55 women) were included in this study. During the median follow-up of 33 months ± 18 (standard deviation), the increased maximal apical FD (≥1.325) had a higher risk of the primary and secondary end points than those with a normal FD (<1.325) (P = .01 and P = .04, respectively). Furthermore, Cox analysis revealed that left ventricular maximal apical FD (hazard ratio range, 1.001-1.008; all P < .05) provided significant prognostic value to predict the primary and secondary end points after adjustment for the European Society of Cardiology predictors and late gadolinium enhancement. Internal validation showed that left ventricular maximal apical FD retained a good performance in predicting the primary end points with an area under the curve of 0.70 ± 0.03. Conclusion Left ventricular apical fractal dimension, which reflects myocardial trabecular complexity, was an independent predictor of the primary and secondary end points in patients with hypertrophic cardiomyopathy. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Captur and Moon in this issue.

Auxiliary diagnostic potential of ventricle geometry and late gadolinium enhancement in left ventricular non-compaction; non-randomized case control study

Background

There are still ambiguities existing in regard to left ventricular non-compaction (LVNC) diagnostic imaging. The aim of our study was to analyze diagnostic potential of late gadolinium enhancement (LGE) and ventricle geometry in patients with LVNC and controls.

Methods

Data on cardiac magnetic resonance imaging (CMR) studies for LVNC were reassessed from the hospital’s database (3.75 years; n=1975 exams). Matching sample of controls included cases with no structural heart disease, hypertrophic or dilative cardiomyopathy, arrhythmogenic right ventricular dysplasia or subacute myocarditis. Eccentricity of the left ventricle was measured at end diastole in the region with pronounced NC and maximal to minimal ratio (MaxMinEDDR) was calculated.

Results

Study included 255 patients referred for CMR, 100 (39.2%) with LVNC (prevalence in the studied period 5.01%) and 155 (60.8%) controls. Existing LGE had sensitivity of 52.5% (95%-CI:42.3–62.5), specificity of 80.4% (95%-CI:73.2–86.5) for LVNC, area under curve (AUC) 0.664 (95%-CI:0.603–0.722);p<0.001. MaxMinEDDR>1.10 had sensitivity of 95.0% (95%-CI:88.7–98.4), specificity of 82.6% (95%-CI: 75.7–88.2) for LVNC, AUC 0.917 (95%-CI:0.876–0.948); p<0.001. LGE correlated with Max-Min-EDD-R (Rho=0.130; p=0.038) and there was significant difference in ROC analysis ΔAUC0.244 (95%-CI:0.175–0.314); p<0.001. LGE also correlated negatively with stroke volume and systolic function (both p<0.05, respectively).

Conclusions

LGE was found to be frequently expressed in patients with LVNC, but without sufficient power to be used as a discriminative diagnostic parameter. Both LGE and eccentricity of the left ventricle were found to be relatively solid diagnostic landmarks of complex infrastructural and functional changes within the failing heart.

The hypertrabeculated (noncompacted) left ventricle is different from the ventricle of embryos and ectothermic vertebrates

Ventricular hypertrabeculation (noncompaction) is a poorly characterized condition associated with heart failure. The condition is widely assumed to be the retention of the trabeculated ventricular design of the embryo and ectothermic (cold-blooded) vertebrates. This assumption appears simplistic and counterfactual. Here, we measured a set of anatomical parameters in hypertrabeculation in man and in the ventricles of embryos and animals. We compared humans with left ventricular hypertrabeculation (N=21) with humans with structurally normal left ventricles (N=54). We measured ejection fraction and ventricular trabeculation using cardiovascular MRI. Ventricular trabeculation was further measured in series of embryonic human and 9 animal species, and in hearts of 15 adult animal species using MRI, CT, or histology. In human, hypertrabeculated left ventricles were significantly different from structurally normal left ventricles by all structural measures and ejection fraction. They were far less trabeculated than human embryonic hearts (15-40% trabeculated volume versus 55-80%). Early in development all vertebrate embryos acquired a ventricle with approximately 80% trabeculations, but only ectotherms retained the 80% trabeculation throughout development. Endothermic (warm-blooded) animals including human slowly matured in fetal and postnatal stages towards ventricles with little trabeculations, generally less than 30%. Further, the trabeculations of all embryos and adult ectotherms were very thin, less than 50 μm wide, whereas the trabeculations in adult endotherms and in the setting of hypertrabeculation were wider by orders of magnitude. It is concluded in contrast to a prevailing assumption, the hypertrabeculated left ventricle is not like the ventricle of the embryo or of adult ectotherms. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.

Non-compact cardiomyopathy or ventricular non-compact syndrome?

Ventricular myocardial non-compaction has been recognized and defined as a genetic cardiomyopathy by American Heart Association since 2006. The argument on the nomenclature and pathogenesis of this kind of ventricular myocardial non-compaction characterized by regional ventricular wall thickening and deep trabecular recesses often complicated with chronic heart failure, arrhythmia and thromboembolism and usually overlap the genetics and phenotypes of other kind of genetic or mixed cardiomyopathy still exist. The proper classification and correct nomenclature of the non-compact ventricles will contribute to the precisely and completely understanding of etiology and its related patho-physiological mechanism for a better risk stratification and more personalized therapy of the disease individually. All of the genetic heterogeneity and phenotypical overlap and the variety in histopathological, electromechanical and clinical presentation indicates that some of the cardiomyopathies might just be the different consequence of myocardial development variations related to gene mutation and phenotype of one or group genes induced by the interacted and disturbed process of gene modulation at different links of gene function expression and some other etiologies. This review aims to establish a new concept of "ventricular non-compaction syndrome" based on the demonstration of the current findings of etiology, epidemiology, histopathology and echocardiography related to the disorder of ventricular myocardial compaction and myocardial electromechanical function development.

Cardiomyopathies: Evolution of pathogenesis concepts and potential for new therapies

Cardiomyopathies are defined as diseases of the myocardium with associated structural and functional abnormalities. Knowledge of these pathologies for a long period was not clear in clinical practice due to uncertainties regarding definition, classification and clinical diagnosis. In recent decades, major advances have been made in the understanding of the molecular and genetic issues, pathophysiology, and clinical and radiological assessment of the diseases. Progress has been made also in management of several types of cardiomyopathy. Advances in the understanding of these diseases show that cardiomyopathies represent complex entities. Here, special attention is given to evolution of classification of cardiomyopathies, with the aim of assisting clinicians to look beyond schematic diagnostic labels in order to achieve more specific diagnosis. Knowledge of the genotype of cardiomyopathies has changed the pathophysiological understanding of their etiology and clinical course, and has become more important in clinical practice for diagnosis and prevention of cardiomyopathies. New approaches for clinical and prognostic assessment are provided based on contemporary molecular mechanisms of contribution in the pathogenesis of cardiomyopathies. The genotype-phenotype complex approach for assessment improves the clinical evaluation and management strategies of these pathologies. The review covers also the important role of imaging methods, particularly echocardiography, and cardiac magnetic resonance imaging in the evaluation of different types of cardiomyopathies. In summary, this review provides complex presentation of current state of cardiomyopathies from genetics to management aspects for cardiovascular specialists.

Magnetic resonance assessment of prevalence and correlates of right ventricular abnormalities in isolated left ventricular noncompaction

The aim of the present study was to evaluate the prevalence and correlates of right ventricular (RV) noncompaction (RVNC), RV systolic dysfunction, and RV myocardial fibrosis in patients with isolated left ventricular (LV) noncompaction (LVNC). For this purpose, cine and contrast-enhanced cardiac magnetic resonance imaging (MRI) was used. A total of 56 consecutive patients with isolated LVNC were included in the study. The diagnosis of isolated LVNC was based on the presence of standard cardiac MRI and clinical criteria. For each patient, cine and contrast-enhanced cardiac MR images were analyzed to evaluate the prevalence and correlates of RVNC, RV dysfunction, and late gadolinium enhancement (a surrogate of myocardial fibrosis) involving the RV. Mean age of the patient population was 45 ± 19 years; 35 patients (63%) were men. RVNC was observed in 5 patients (9%). Impaired RV systolic function was observed in 9 patients (16%). Late gadolinium enhancement was not observed in any RV segment. No association was found between wall motion abnormalities and noncompaction at RV segmental level (φ coefficient 0.041, p = 0.26). At multivariate analysis, LV ejection fraction was the only variable independently related to RV ejection fraction (β = 0.62, p <0.001). In conclusion, RV systolic dysfunction is present in a non-negligible proportion of patients with isolated LVNC; LV systolic function is the only variable independently related to RV systolic function.

Relationship between left ventricular sphericity and trabeculation indexes in patients with dilated cardiomyopathy: a cardiac magnetic resonance study

AIMS

To study the relationship between left ventricular (LV) trabeculations, volume, and sphericity in patients with dilated cardiomyopathy (DCM) by cardiac magnetic resonance imaging (CMR).

METHODS AND RESULTS

Eighty-two patients with DCM were prospectively explored by CMR. The segmental trabeculation index (STI) was defined by the ratio of trabeculated layer thickness on compacted layer thickness per segment. The global trabeculation index (GTI) was defined by the ratio of the sum of the total trabeculated layer thickness to the sum of the total compacted layer thickness. The apex was excluded from the analysis. The mean number of segments with trabeculation per patient was 10 ± 2 with a mean GTI of 0.68 ± 0.32. The LV sphericity index was inversely correlated with LV ejection fraction (R = -0.42, P = 0.0002) and positively with the brain natriuretic peptide (BNP) level (R = 0.34, P = 0.003). The maximal STI was positively correlated with the indexed LV end-diastolic volume (R = 0.32, P = 0.004) and the LV sphericity index (R = 0.25, P = 0.02), but not with the BNP level or LV ejection fraction. The GTI was positively correlated with the LV sphericity index (R = 0.27, P = 0.016) but not with indexed LV end-diastolic volume, BNP levels, or LV ejection fraction.

CONCLUSION

Trabeculation indexes depend on LV shape and are positively correlated with LV sphericity. These results encourage interpreting LV trabeculation with caution in patients with DCM, considering additional morphologic criteria such as LV geometry.