Reduced Systolic Function and Not Genetic Variants Determine Outcome in Pediatric and Adult Left Ventricular Noncompaction Cardiomyopathy

Advances and challenges in the diagnosis and management of left ventricular noncompaction in adults: A literature review

In the realm of cardiovascular health, isolated left ventricular noncompaction (LVNC) stands out for its distinct morphological features and the clinical challenges it presents, particularly in adults. This literature review explores the intricacies of LVNC, aiming to unravel its epidemiological spread, diagnostic hurdles, and therapeutic strategies. Despite technological advancements in cardiac imaging that have improved the recognition of LVNC, a significant gap persists alongside a fragmented understanding of its pathogenesis. The studies scrutinized reveal a broad spectrum of prevalence rates influenced by diverse diagnostic tools and demographic variables. This variation underscores the complexity of accurately identifying LVNC and the resultant implications for clinical management. The review succinctly addresses the need for precise guidelines to navigate the diagnosis of LVNC and outlines the imperative for tailored clinical management approaches that cater to the wide array of patient presentations, from asymptomatic cases to those with severe cardiac dysfunction. By highlighting the critical gaps in current literature-namely the absence of standardized diagnostic criteria and a comprehensive pathogenic model-the review sets the stage for future research directions. These endeavors are essential for enhancing diagnostic accuracy, refining management protocols, and ultimately improving patient outcomes in this complex subset of cardiomyopathy, thus contributing significantly to the advancement of cardiovascular medicine.

Exploring TTN variants as genetic insights into cardiomyopathy pathogenesis and potential emerging clues to molecular mechanisms in cardiomyopathies

The giant protein titin (TTN) is a sarcomeric protein that forms the myofibrillar backbone for the components of the contractile machinery which plays a crucial role in muscle disorders and cardiomyopathies. Diagnosing TTN pathogenic variants has important implications for patient management and genetic counseling. Genetic testing for TTN variants can help identify individuals at risk for developing cardiomyopathies, allowing for early intervention and personalized treatment strategies. Furthermore, identifying TTN variants can inform prognosis and guide therapeutic decisions. Deciphering the intricate genotype-phenotype correlations between TTN variants and their pathologic traits in cardiomyopathies is imperative for gene-based diagnosis, risk assessment, and personalized clinical management. With the increasing use of next-generation sequencing (NGS), a high number of variants in the TTN gene have been detected in patients with cardiomyopathies. However, not all TTN variants detected in cardiomyopathy cohorts can be assumed to be disease-causing. The interpretation of TTN variants remains challenging due to high background population variation. This narrative review aimed to comprehensively summarize current evidence on TTN variants identified in published cardiomyopathy studies and determine which specific variants are likely pathogenic contributors to cardiomyopathy development.

The Trouble with Trabeculation: How Genetics Can Help to Unravel a Complex and Controversial Phenotype

Excessive trabeculation of the cardiac left ventricular wall is a complex phenotypic substrate associated with various physiological and pathological processes. There has been considerable conjecture as to whether hypertrabeculation contributes to disease and whether left ventricular non-compaction (LVNC) cardiomyopathy is a distinct pathology. Building on recent insights into the genetic basis of LVNC cardiomyopathy, in particular three meta-analysis studies exploring genotype-phenotype associations using different methodologies, this review examines how genetic research can advance our understanding of trabeculation. Three groups of genes implicated in LVNC are described-those associated with other cardiomyopathies, other cardiac/syndromic conditions and putatively with isolated LVNC cardiomyopathy-demonstrating how these findings can inform the underlying pathologies in LVNC patients and aid differential diagnosis and management in clinical practice despite the limited utility suggested for LVNC genetic testing in recent guidelines. The outstanding questions and future research priorities for exploring the genetics of hypertrabeculation are discussed.

Can left ventricular entropy by cardiac magnetic resonance late gadolinium enhancement be a prognostic predictor in patients with left ventricular non-compaction?

PURPOSE

Left ventricular non-compaction (LVNC) is considered rare; however, the use of cardiac magnetic resonance (CMR) has shown that its incidence is not uncommon, and its clinical presentation remains variable, with an uncertain prognosis. Risk stratification of major adverse cardiac events (MACE) in patients with LVNC remains complex. Therefore, this study aims to determine whether tissue heterogeneity from late gadolinium enhancement-derived entropy is associated with MACE in patients with LVNC.

METHODS

This study was registered in the Clinical Trial Registry (CTR2200062045). Consecutive patients who underwent CMR imaging and were diagnosed with LVNC were followed up for MACE, which was defined by heart failure, arrhythmias, systemic embolism, and cardiac death. The patients were divided into MACE and non-MACE groups. The CMR parameters included left ventricular (LV) entropy, LV ejection fraction (LVEF), LV end-diastolic volume, LV end-systolic volume (LVESV), and LV mass (LVM).

RESULTS

Eighty-six patients (age: 45.48 ± 16.64 years; female: 62.7%; LVEF: 42.58 ± 17.20%) were followed up for a median of 18 months and experienced 30 MACE events (34.9%). The MACE group showed higher LV entropy, LVESV, and LVM and lower LVEF than the non-MACE group. LV entropy [hazard ratio (HR): 1.710, 95% confidence interval (CI): 1.078-2.714, P = 0.023] and LVEF (HR: 0.961, 95% CI: 0.936-0.988, P = 0.004) were independent predictors of MACE (P <0.050) according to the Cox regression analysis. Receiver operating characteristic curve analysis revealed that the area under the curve of LV entropy was 0.789 (95% CI: 0.687-0.869, P < 0.001), LVEF was 0.804 (95% CI: 0.699-0.878, P < 0.001), and the combined model of LV entropy and LVEF was 0.845 (95% CI: 0.751-0.914, P < 0.050).

CONCLUSION

LGE-derived LV entropy and LVEF are independent risk indicators of MACE in patients with LVNC. The combination of the two factors was more conducive to improving the prediction of MACE.

Advances in symptomatic therapy for left ventricular non-compaction in children

Left ventricular non-compaction is a complex cardiomyopathy and the third largest childhood cardiomyopathy, for which limited knowledge is available. Both pathogenesis and prognosis are still under investigation. Currently, no effective treatment strategy exists to reduce its incidence or severity, and symptomatic treatment is the only clinical treatment strategy. Treatment strategies are constantly explored in clinical practice, and some progress has been made in coping with the corresponding symptoms because the prognosis of children with left ventricular non-compaction is usually poor if there are complications. In this review, we summarized and discussed the coping methods for different left ventricular non-compaction symptoms.

Left Ventricular Noncompaction in Children: The Role of Genetics, Morphology, and Function for Outcome

Left ventricular noncompaction (LVNC) is a ventricular wall anomaly morphologically characterized by numerous, excessively prominent trabeculations and deep intertrabecular recesses. Accumulating data now suggest that LVNC is a distinct phenotype but must not constitute a pathological phenotype. Some individuals fulfill the morphologic criteria of LVNC and are without clinical manifestations. Most importantly, morphologic criteria for LVNC are insufficient to diagnose patients with an associated cardiomyopathy (CMP). Genetic testing has become relevant to establish a diagnosis associated with CMP, congenital heart disease, neuromuscular disease, inborn error of metabolism, or syndromic disorder. Genetic factors play a more decisive role in children than in adults and severe courses of LVNC tend to occur in childhood. We reviewed the current literature and highlight the difficulties in establishing the correct diagnosis for children with LVNC. Novel insights show that the interplay of genetics, morphology, and function determine the outcome in pediatric LVNC.