Non-compaction of the left ventricle

Non-compaction of the left ventricle, also known as spongiform cardiomyopathy or left ventricular non-compaction (LVNC) is a phenotype of hypertrophic ventricular trabeculations and deep interventricular recesses. It has been hypothesized to result from arrest of normal myocardial compaction during embryogenesis, although acquired cases have also been reported.

Non-compaction of the right ventricle has been described, but is rare 3.

There is controversy as to whether LVNC represents a distinct disease versus a phenotypic manifestation of various cardiomyopathies 9. For example, although LVNC is classified as a primary genetic cardiomyopathy by the American Heart Association, it remains unclassified by both the World Health Organization and the European Society of Cardiology 9.

At least some of the inconsistency is due to the fact that LVNC is mostly diagnosed by morphological criteria on non-invasive imaging (e.g. echocardiography and cardiac MRI), and no universally-accepted criteria exist.

Additionally, findings of LVNC may be seen in a spectrum of clinical presentations. It may be seen as a component of cardiomyopathy, such as in Barth syndrome, or in concert with other myocardial structural/functional abnormalities (e.g. dilated, restrictive, arrhythmogenic right ventricular cardiomyopathies); however, it may be acquired/reversible and/or observed in subjects with normal left ventricular function and size.

Thus, findings of LVNC should not be equated with cardiomyopathy or aberrant left ventricular function, as the findings The findings should be integrated into a holistic evaluation of cardiac function in deciding a final diagnosis 6.

While LVNC may be an isolated morphological variant, discovered in patients with otherwise structurally and functionally normal hearts, it may also present as a component of a congenital heart disease or true cardiomyopathy; in this latter instance it may present as congestive heart failure. Other presenting features may include 8:

  • exertional syncope
    • may be associated with a long QT interval
      • may predispose to a subtype of polymorphic ventricular tachycardia, torsades de pointes 
  • atrial fibrillation
  • systemic thromboembolic events
    • may lead to transient ischemic attacks or stroke

In most patients with non-compaction of the left ventricle, there are no other cardiac malformations. Familial and sporadic form have been described 1. However, in at least one study, approximately 12% of patients had associated cardiac malformations 1:

Chest radiographs are not useful in the diagnosis of non-compaction of the left ventricle. They are more useful in identifying complications of the cardiomyopathy, such as pulmonary edema and cardiomegaly.

Echocardiography was traditionally used in the diagnosis of left ventricular non-compaction, with the addition of contrast greatly increasing the sensitivity of this examination. However, cardiac MRI is now considered the modality of choice to make this diagnosis. There are no universally accepted echocardiographic criteria for left ventricular non-compaction. Most common echocardiographic features include 7:

  • bilayered mural appearance of left ventricle
    • the relatively hypoechoic inner layer of left ventricular wall representing the endocardium/myocardium is hypertrabeculated
      • referred to as the non-compacted or "NC" layer
    • the non-compacted layer is surrounded by the outer "compacted" layer, representing the epicardium
    • classical definition based on the NC/C thickness ratio
      • increased thickness of the NC layer with an NC/C ratio >2.3 consistent with diagnosis
  • regional increase in left ventricular trabeculaction
    • predominantly affects the inferolateral walls and the apex
    • the parasternal short axis (or apical four/two/long axis view) should reveal at least four trabeculations
  • pronounced inter-trabecular "crypts" or recesses

Other commonly associated features include:

Cardiac MRI has a better contrast resolution than echocardiography and it is the modality of choice for the diagnosis of spongiform cardiomyopathy. The best diagnostic clue is a ratio of non-compacted telediastolic myocardium to compacted telediastolic myocardium of more than 2.3:1 (sensitivity: 86%, specificity: 99%).

The only definitive treatment of left ventricular non-compaction is cardiac transplantation. Otherwise, prevention of both heart failure and thromboembolic events are the main target of treatments.

Possible differential considerations in certain situations include:

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Article information

rID: 20889
System: Cardiac
Synonyms or Alternate Spellings:
  • Spongiform cardiomyopathy
  • LV noncompaction
  • Spongy myocardium
  • Left ventricular hypertrabeculation
  • Noncompacted myocardium
  • Noncompaction of the left ventricle
  • Non compaction cardiomyopathy
  • Left ventricular non compaction

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