Left Ventricular Non-Compaction (LVNC)

Left ventricular non-compaction (LVNC), also known as ventricular hypertrabeculation, is a rare congenital cardiomyopathy. This condition is characterized by a unique and prominent trabecular meshwork and deep intratrabecular recesses, leading to a distinctive appearance of a two-layered myocardium: a thin, compacted epicardial layer and a thick, non-compacted endocardial layer.

Etiology and Genetics

LVNC can occur in isolation or in conjunction with other cardiac anomalies (such as Ebstein, ventricular septal defects or other anomalies). While the exact cause is still under investigation, studies suggest that it may be due to an arrest in the normal process of endomyocardial morphogenesis during fetal development. Genetic factors have been strongly implicated, with many cases displaying an autosomal dominant inheritance pattern.

Several genes associated with LVNC have been identified, including MYH7, MYBPC3, and TTN, among others. Genetic counseling and testing may be considered in some cases to determine risk in siblings and for future offspring.

Clinical Presentation

The clinical presentation of LVNC in newborns varies widely, from asymptomatic to severe heart failure. The variability in presentation is believed to be due to differences in the degree and location of non-compaction, and possibly the co-occurrence of other cardiac abnormalities. Symptoms may include poor feeding, failure to thrive, difficulty breathing, and excessive fatigue or lethargy.

Diagnosis

Diagnosis of LVNC is usually established through echocardiography, which reveals the characteristic appearance of a two-layered myocardium. Additional imaging modalities like Cardiac Magnetic Resonance Imaging (CMRI) may be used to confirm the diagnosis.

Specific echocardiographic criteria for LVNC have been proposed, although there is currently no universally accepted standard. The most commonly used criteria include the ratio of non-compacted to compacted myocardium, with a ratio greater than 2.0 in end-systole generally considered diagnostic.

• Jenni Criteria: This includes the presence of numerous prominent trabeculations and deep intertrabecular recesses. It defines non-compacted to compacted myocardial ratio greater than 2:1 measured at end-systole in the parasternal short-axis view as diagnostic of LVNC.

• Chin et al. Criteria: It includes the presence of two distinct myocardial layers, a thin, compacted epicardial layer, and a much thicker non-compacted endocardial layer with prominent trabeculations and deep intertrabecular recesses.

• Stöllberger and Finsterer Criteria: In addition to features of two distinct myocardial layers, it requires the presence of color Doppler flow within the deep intertrabecular recesses.

• Petersen et al. Criteria: Non-compacted to compacted myocardial ratio of > 2.3:1 at end-diastole on cardiac magnetic resonance imaging (CMR) was diagnostic of LVNC in their study. Although this criterion was designed for CMR, some practitioners use it for echo as well.

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Newborn with hypertrabeculations at the Apex and concern for noncompaction:

Management and Prognosis

Management of LVNC in newborns is largely symptomatic and aims to manage and prevent heart failure and arrhythmias, which are the most common complications. Treatment may include medications, such as ACE inhibitors, beta-blockers, and diuretics. In the context of cardiac failure, there is an increased risk of clot and some of these patients may require anti-coagulation. 

In severe cases, or in the event of progressive heart failure, cardiac transplantation may be considered. Regular follow-up with a pediatric cardiologist is essential to monitor the condition and adjust treatment as needed.

Prognosis varies and can be influenced by factors such as the severity of the condition, the presence of other congenital heart defects, and the newborn's overall health.

Conclusion

LVNC is a complex and heterogeneous disorder. While advances in genetics and imaging modalities have increased our understanding of this condition, further research is required to elucidate its pathophysiology, optimize diagnostic criteria, and improve management and outcomes for affected newborns. Continuing education and awareness among healthcare professionals in the field of pediatric cardiology are crucial for early detection and timely intervention.

Article highlight: Bennett CE, Freudenberger R. The Current Approach to Diagnosis and Management of Left Ventricular Noncompaction Cardiomyopathy: Review of the Literature. Cardiol Res Pract. 2016;2016:5172308. doi: 10.1155/2016/5172308.