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Key Questions Relating to Left Ventricular Noncompaction Cardiomyopathy: Is the Emperor Still Wearing Any Clothes?
Robert H Anderson1, Bjarke Jensen2, Timothy J Mohun3
1Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, United Kingdom; Division of Biomedical Sciences, University College London, London, United Kingdom.
Insights
Left ventricular noncompaction cardiomyopathy is likely not a distinct disease. Excessive trabeculation alone does not indicate a poor prognosis in adults with normal ejection fraction.
Area of Science:
- Cardiology
- Developmental Biology
- Pathology
Background:
- Left ventricular noncompaction cardiomyopathy (LVNC) is a rare genetic heart muscle disorder.
- It is characterized by excessive prominent trabeculations and deep intertrabecular recesses in the left ventricle.
- Current diagnostic criteria may not accurately reflect the underlying pathophysiology.
Purpose of the Study:
- To critically evaluate the definition and diagnostic criteria of left ventricular noncompaction cardiomyopathy.
- To investigate the clinical significance of excessive left ventricular trabeculation.
- To determine if LVNC represents a distinct disease entity.
Main Methods:
- Review of existing literature and diagnostic criteria for LVNC.
- Analysis of clinical data from adult and pediatric populations with excessive ventricular trabeculation.
- Comparison of imaging findings across different age groups and clinical presentations.
Main Results:
- Evidence suggests LVNC is not a failure of embryonic myocardial compaction.
- Excessive trabeculation in adults with normal ejection fraction is associated with a good prognosis.
- Clinical features in adults differ significantly from those in children or autopsy studies.
- Excessive trabeculation may be an incidental finding or a bystander to other cardiac conditions.
Conclusions:
- The term "noncompaction cardiomyopathy" may be misleading.
- Excessive left ventricular trabeculation is not necessarily indicative of a cardiomyopathic process.
- Re-evaluation of diagnostic criteria and clinical significance of LVNC is warranted.
Abstract:
The evidence is increasing that left ventricular noncompaction cardiomyopathy as it is currently defined does not represent a failure of compaction of pre-existing trabecular myocardium found during embryonic development to form the compact component of the ventricular walls. Neither is there evidence of which we are aware to favour the notion that the entity is a return to a phenotype seen in cold-blooded animals. It is also known that when seen in adults, the presence of excessive ventricular trabeculations does not portend a poor prognosis when the ejection fraction is normal, with the risks of complications such as arrhythmia and stroke being rare in this setting. It is also the case that images of "noncompaction" as provided from children or autopsy studies are quite different from the features observed clinically in asymptomatic adults with excessive trabeculation. Our review suggests that the presence of an excessively trabeculated left ventricular wall is not in itself a clinical entity. It is equally possible that the excessive trabeculation is no more than a bystander in the presence of additional lesions such as dilated cardiomyopathy, with the additional lesions being responsible for the reduced ejection fraction bringing a given patient to clinical attention. We, therefore, argue that the term "noncompaction cardiomyopathy" is misleading, because there is neither failure of compaction nor a cardiomyopathic process in most individuals that fulfill widely used diagnostic criteria.