Episode Schematics & Teaching

The etiology has been a constant debate since 1980. It has been debated among researchers and clinicians whether LVNC is a physiologic or a pathologic manifestation. Waning et al., classified 327 unrelated patients into 3 categories: 1) genetic, 2) probably genetic, or 3) sporadic, identifying the most common mutations: MYH7, MYBPC3 and TTN in the genetic LVNC patients, which mostly encode for sarcomere, Z-disc and nuclear-envelope proteins. This supports the hypothesis that the inherited phenotype can arise from a gene mutation possibly during embryogenesis, disrupting the physiologic compaction of normally developing myocardium, which progresses from the base to the apex of the cardiac tissue. It is estimated that genetic LVNC accounts approximately 18-44% of cases, with autosomal dominant transmission being the most common form of inheritance. Physiologic remodeling with prominent trabeculations may be noted in athletes and pregnant women, in comparison to pathologic remodeling which may be encountered in patients with cardiomyopathy (e.g. pressure or volume load).  (1)

There is no pathognomonic signs or symptoms in LVNC. LVNC patients may encounter various potential clinical characteristics. Presentations are myriad and include heart failure symptoms (HFrEF or HFpEF), ventricular tachycardia (VT/VF), atrial fibrillation, thromboembolism including cerebrovascular accident (CVA), and syncope. In a cohort of 95 probands with LVNC investigated in Europe, as many as 32.3% had an ICD/CRT-D implantation, with 11.8% experiencing a cardiovascular death and 18.2% having an appropriate ICD shock. (2)

Imaging plays a key role in diagnosis for LVNC. The identification and diagnosis of LVNC is evaluated using 2D echocardiography. The initial proposed method by Chin et al., evaluated the size of the trabeculation in the center. (3) The most commonly used criteria, Jenni et al. (4), entail the following four finding:

• Two-layer structure, with a thin compacted layer and a thick non-compacted layer measure at end-systole at the parasternal short-axis view. LVNC is defined by a ratio of N/C > 2
• Absence of co-existing cardiac structural abnormalities
• Prominent, excessive trabeculations and deep intra-trabecular recesses
• Recesses supplied by intraventricular blood on color doppler

Cardiac MRI has increased the diagnostic accuracy in the diagnosis of LVNC. It has been suggested that a NC/C ratio of > 2.3 in diastole distinguished pathological non-compaction, with sensitivity of 86% and a specificity of 99%, respectively. Although studies have shown an increase specificity with cardiac MRI, caution is needed as it may overestimate the presence of LVNC. Late gadolinium enhancement which suggests myocardial fibrosis or scar has been shown to have some prognostic value in LVNC patients. (5)

Management for LVNC is multifaceted. As above,LVNC has a variety of presentations and prevailing manifestations will differ among patients. Therefore, the diagnostic and management approach much be personalized for a given patient.

Heart failure with reduced ejection fraction is the most common presentation, thus treatment follows guided directed medical therapy, including ACEi/ARB/ARNi, beta-blockers, MRA, SGLT2i, etc. The risk for thromboembolism in patients with LVNC has not been well-established although case-series have noted an increase in clot formation due to the increase in intertrabecular recesses. Although no definitive criteria for anticoagulation have been suggestive in patients with LVNC and atrial fibrillation who meet current recommendations. There is a weak recommendation for anticoagulation in patients with LVNC and LVEF < 40% with or without atrial fibrillation. (6) Arrhythmias in LVNC is frequent.

Ambulatory rhythm monitoring may be used to detect atrial fibrillation and ventricular arrhythmias. As with our patient, individuals with LVNC who survive an episode of sustained ventricular tachycardiac or sudden cardiac death, an ICD is indicative as secondary prevention.  Otherwise, LVNC in patients with LVEF ≤ 35 percent and NYHA class II to III heart failure, ICD implantation is suggested. (6)

Patients should be referred for genetic counseling with testing and subsequent cascade family screening as appropriate. Genetic testing has an important role in the management of LVNC. The identification of genetic LVNC is more predictive of major adverse cardiovascular events in the pediatric population than in adults, based on the finding from Waning et al. It has also been noted that patients with left ventricular dysfunction predicted a higher risk of MACE in carriers of the mutation compared to nongenetic cases. 

The 2018 Heart Failure Society of America (HFSA) guideline recommends a careful family history for at least three generation and screening of first-degree relatives of all patients with LVNC. Clinical screening should include physical history, echocardiogram, physical examination, electrocardiogram, and creatinine kinase. The HFSA recommends genetic testing for the individual displaying the most affect phenotype of disease. If the individual displays an abnormal disease-causing gene-variant then first degree relatives are recommended to undergo clinical screening for the disease followed by genetic counseling. (7)