Left ventricular noncompaction (LVNC) is a heart muscle disorder characterized by excessive trabeculations and deep recesses in the left ventricle. It is diagnosed using echocardiography or cardiac MRI based on specific criteria. Symptoms vary and include heart failure, arrhythmias, and thromboembolic events like stroke. The cause involves abnormal heart muscle development during fetal life. Genetic factors are involved in some cases. Treatment focuses on managing symptoms and complications. Prognosis depends on the severity of symptoms and complications.

1. Left Ventricular Non
compaction
(BSc Cardiac Tech)
DR.S.R.SRUTHI MEENAXSHI

2. Left ventricular noncompaction (LVNC) is a distinct phenotype characterized by prominent LV
trabeculae and deep intertrabecular recesses .
LVNC was previously also called spongy myocardium or hypertrabeculation syndrome but these
terms should not be used interchangeably with LVNC .
This review will focus on clinical manifestations and diagnosis of LVNC as an isolated disorder
distinct from other clinical settings in which non-compacted myocardium may be seen in
association with other cardiac and noncardiac abnormalities.

3. By definition, isolated LVNC occurs in the absence of other cardiac or noncardiac congenital abnormalities. (
Although LVNC has been categorized as an "unclassified" cardiomyopathy mounting evidence now points to
reclassification of LVNC as a distinct but not always pathological phenotype.
The presence of noncompacted myocardium by itself does not seem to cause disease. LVNC is a condition
resulting from genetics interacting with environment that is best labeled as a phenotype
LVNC is characterized by the following features:
●An altered myocardial wall with prominent trabeculae and deep intertrabecular recesses, resulting in thickened
myocardium with two layers consisting of noncompacted myocardium and a thin compacted layer of myocardium .
●Continuity between the LV cavity and the deep intertrabecular recesses, which are filled with blood from the
ventricular cavity without evidence of communication to the epicardial coronary artery system.
As discussed below, criteria for the extent of noncompaction have been developed to help distinguish the
trabeculation seen in LVNC from that seen in other forms of heart disease and in healthy individuals.
However, criteria are evolving and there may be morphologic overlap between LVNC and other types of
cardiomyopathy and other pathologic and nonpathologic phenotypes.

5. LVNC is characterized by the following features:
●An altered myocardial wall with prominent trabeculae and deep intertrabecular recesses,
resulting in thickened myocardium with two layers consisting of noncompacted myocardium and
a thin compacted layer of myocardium .
●Continuity between the LV cavity and the deep intertrabecular recesses, which are filled with
blood from the ventricular cavity without evidence of communication to the epicardial coronary
artery system.

6. ◦ As discussed below, criteria for the extent of noncompaction have been
developed to help distinguish the trabeculation seen in LVNC from that seen in
other forms of heart disease and in healthy individuals.
◦ However, criteria are evolving and there may be morphologic overlap between
LVNC and other types of cardiomyopathy and other pathologic and
nonpathologic phenotypes

7. The prevalence of LVNC in the general population is not known, but its prevalence among patients undergoing
echocardiography is estimated at 0.014 to 1.3 percent .
A review from Switzerland identified 34 cases within 15 years, which represented 0.014 percent of
echocardiograms performed.
However, this may be an underestimate, since improved echocardiographic image quality, increased detection of
the entity on non-echo imaging, and increasing awareness of LVNC will likely lead to enhanced recognition of this
echocardiographic phenotype. Among patients with heart failure (HF), the prevalence of LVNC has been reported
as 3 to 4 percent .
Among patients with HF, criteria for LVNC are more frequently met among black patients than among white
patients .
One difficulty in ascertaining the prevalence of LVNC is that a variety of morphologic criteria for LVNC have been
applied; criteria for LVNC are evolving and likely have varying specificity in different populations.
As examples, most studies have not included wall thickness <8.1 mm as a criterion, and the morphology of
papillary muscles has seldom been addressed.

8. PATHOGENESIS
It has been suggested that LVNC may be due to intrauterine arrest of compaction of the loose
interwoven meshwork that makes up the fetal myocardial primordium.
However, the term "noncompaction" may be a misnomer: some authors have suggested that
noncompaction of the ventricular myocardium results from abnormal persistence of the trabecular
layer, rather than from noncompaction of the ventricular wall .
Pronounced hypertrabeculation may be the result of altered regulation in cell proliferation,
differentiation, and maturation during ventricular wall formation .
Trabeculations of the LV may be unique for each individual, like fingerprints .
Prominent trabeculations as seen in LVNC may develop during adult life.
Remodeling in response to LV loading conditions may explain the phenotypic characteristics of LVNC
seen in some athletes and in some individuals who are hypertensive, pregnant, or have heart failure
or hematologic disorders (eg, β-thalassemia) .
Additionally, LVNC can occur as a transient phenomenon in patients with other disorders, such as
myocarditis.

9. GENETICS
LVNC can be either sporadic or familial. In various reports, 12 to 50 percent of those with LVNC
had a family history of LVNC .
Other affected individuals can be detected by screening asymptomatic relatives of affected
patients .
Autosomal dominant inheritance is more common than X-linked inheritance or autosomal
recessive inheritance .
Differentiation of genotypes is not possible on the basis of current phenotypic data. The yield of
genetic testing in patients with LVNC is around 40 to 50 percent .

10. ◦ There is increasing recognition of considerable overlap in the genetic loci implicated in the major cardiomyopathies.
◦ Shared molecular etiology has been found for different cardiomyopathic phenotypes, including overlapping phenotypes between LVNC
and hypertrophic cardiomyopathy (HCM) and between LVNC and apical HCM .
◦ Despite the genetic overlap between LVNC and HCMs, LVNC co-occurs more commonly than HCM in patients with congenital heart
disease or Wolff-Parkinson-White syndrome.

11. CLINICAL MANIFESTATIONS
Clinical manifestations of LVNC are variable and may include dyspnea, chest pain, palpitations, syncope, or an abnormal electrocardiogram (ECG) or echocardiogram .
Cardiac symptoms and signs may not be present. The major complications of LVNC are HF, atrial and ventricular arrhythmias, sudden cardiac arrest, and thromboembolic
events, including stroke .
Symptoms and signs — The frequency of these manifestations at presentation is dependent on the population studied.
The following report is illustrative. In a systematic review including five studies with a total of 241 adult patients, 56 percent of patients were referred for HF, 27 percent were
referred for suspected LVNC based on prior clinical evaluation, and 11 percent were identified by screening . Baseline characteristics included the following:
•Dyspnea – 60 percent
•Chest pain − 15 percent
•Palpitations − 18 percent
•Syncope or presyncope − 9 percent
•Prior stroke – 3 percent
•New York Heart Association (NYHA) functional class III or IV HF – 31 percent
An increasing number of patients with isolated LVNC are initially diagnosed during childhood, however, criteria for diagnosis in children have not been established in large
studies . Initial diagnosis by prenatal ultrasound has been reported [47]. Similar presenting symptoms and signs have been reported in children

12. Complications — Complications of LVNC include HF, thromboembolism, and arrhythmias.
Heart failure — As noted above, among patients with LVNC, symptoms and signs of HF are
common at presentation, and hospitalization for HF is common .
Patients with LVNC can present as HF with reduced ejection fraction (HFrEF; LV ejection fraction
[LVEF] ≤40 percent), or less commonly, HF with preserved ejection fraction (HFpEF: LVEF ≥50
percent) or HF with mid-range ejection fraction (HFmrEF; LVEF 41 to 49 percent).

13. Thromboembolism — The risk of thromboembolism in patients with LVNC has not been
established. Given the available data, it is not clear whether the thromboembolic rate in patients
with LVNC differs from the rate generally observed in patients with HF.
. Patients with stroke or embolism had higher rates of hypertension and higher CHADS2 and
CHA2DS2-VASc scores than patients without stroke or embolism. LV fractional shortening was
similar in patients with and without a stroke or embolism event.
Atrial fibrillation was nominally more frequent in patients with stroke or embolic event but there
was no significant difference compared to patients without an event.

14. Arrhythmias — Ventricular and atrial arrhythmias occur commonly in patients with LVNC. In a
systematic review, 33 percent of patients had nonsustained ventricular tachycardia and 5
percent had sustained ventricular tachycardia .
Atrial fibrillation was documented in 10 percent of patients. There are no data on the sudden
cardiac death (SCD) risk of athletes with LVNC. LVNC has not been described in autopsy studies
of athletes with SCD; however, LVNC could have been missed at autopsy or described as HCM.
Initial testing — An ECG is commonly obtained in patients with suspected LVNC. The ECG is
usually abnormal (32 of 34 patients in the above report), but findings are nonspecific.
The abnormalities that may be seen include left or right bundle branch block, fascicular block,
atrial fibrillation, and ventricular tachycardia. Sinus bradycardia or Wolff-Parkinson-White
syndrome has been described in up to 18 percent of pediatric patients with LVNC .
The role of echocardiography and other cardiac imaging in the diagnosis of LVNC is described
below.

16. Echocardiography
Echocardiography criteria — Echocardiography is the test most commonly used both to
establish the diagnosis of LVNC and as an aid during follow-up .For diagnosis of LVNC using
echocardiography, we use the Jenni criteria, which are the most widely accepted validated
criteria.
Alternatively, some clinicians use the Chin or Stöllberger criteria, which have also been
validated.
●The Jenni criteria were developed based upon echocardiographic appearance with pathologic
confirmation in seven patients with LVNC; the criteria were validated in a second population .
The criteria are assessed in the parasternal short-axis view at base, mid, and apical levels.

17. The presence of all four of the following echocardiographic criteria are required for diagnosis:
•A thickened LV wall consisting of two layers: a thin compacted epicardial layer and a markedly
thickened endocardial layer with numerous prominent trabeculations and deep recesses with a
maximum ratio of noncompacted to compacted myocardium >2:1 at end-systole in the parasternal
short-axis view .
•Color Doppler evidence of flow within the deep intertrabecular recesses.
•Prominent trabecular meshwork in the LV apex or midventricular segments of the inferior and lateral
wall.
•Compacted wall thickness ≤8.1 mm. The criterion of maximal systolic compacta thickness of ≤8.1 mm
was found to be very specific for myocardial thickening in LVNC compared to normal controls or
patients with aortic stenosis
In addition, hypokinesis of noncompacted segments and possibly other adjoining segments may be
present.

22. The Chin criterion is based upon observations
from eight patients :
The presence of X/Y ≤0.5, where X is the distance from the epicardial surface to the trough of
the trabecular recess and Y is the distance from the epicardial surface to peak of trabeculation.
This criterion is applied to trabeculae at the LV apex on subxiphoid or apical four-chamber views
at end-diastole.

23. Stöllberger criteria emphasize
hypertrabeculation :
●More than three trabeculations protruding from the LV wall, apically to the papillary muscles,
visible in a single image plane.
• Intertrabecular spaces perfused from the ventricular cavity, visualized on color Doppler
imaging.
The role for contrast echocardiography has been incompletely evaluated in LVNC; in our
practice, we routinely use contrast echocardiography for diagnosis of LVNC in patients with
suboptimal image quality to help differentiate LVNC from apical HCM, eosinophilic
endomyocardial disease, and from apical thrombi.
A role for three-dimensional echocardiography in LVNC has not been established.
A three-dimensional echocardiographic study found significantly higher trabeculated LV volume
and trabeculated LV volume normalized by LV end-diastolic volume in patients with LVNC
compared to healthy controls and athletes

26. Other echocardiographic findings —
Nonspecific findings that may be seen on echocardiography include reduced global LV systolic
function, diastolic dysfunction, LV thrombi, and abnormal papillary muscle structure .
Absence of well-defined papillary muscles is a very typical finding of LVNC .
Tissue Doppler imaging has been used to assess patients with LVNC. The diagnostic benefit of
strain and strain rate imaging and speckle tracking in LVNC has yet to be determined.
As noted above, the echocardiographic appearance of isolated LVNC is heterogenous, including
dilated forms, hypertrophic variant, and restrictive types

27. Cardiovascular magnetic resonance imaging — CMR is generally used to aid in the diagnosis of
LVNC when echocardiographic findings are inconclusive.
In addition, since CMR provides morphologic information (including identification of fibrosis by
late gadolinium enhancement (LGE) which may have prognostic implications) that differs from
that provided by echocardiography, we perform it once in most patients to confirm the diagnosis
of LVNC and repeat it as indicated during follow-up as a component of the evaluation for
evolving clinical symptoms and complications.

29. Various CMR criteria have differing sensitivity and specificity for LVNC. In a study comparing four
different CMR criteria for LVNC, 3 to 39 percent of patients referred for CMR fulfilled LVNC
criteria .
The Stöllberger echocardiographic criteria for LVNC may be insensitive when applied to CMR .
In a series of 19 LVNC patients diagnosed by echocardiography using the Stöllberger criteria,
only nine met these criteria on CMR (obtained in short- and long-axis views).
However, the overall CMR morphologic appearance in all cases confirmed the diagnosis of
LVNC.

30. CMR may be superior to standard echocardiography in assessing the extent of noncompaction
as suggested by a small study comparing CMR with echocardiography in 16 patients with LVNC .
All 17 left ventricular segments could be analyzed by CMR whereas 88 percent of segments
could be analyzed by echocardiography at end-diastole and 87 percent of segments could be
analyzed by echocardiography at end-systole.
A two-layer structure was identified in more segments by CMR than by the echocardiographic
methods. There was no significant difference between the maximum ratio of
noncompacted/compacted layers by CMR and echocardiography at end-diastole.
Echocardiography at end systole underestimated the ratio of noncompacted/compacted layers
compared to CMR.

31. Late gadolinium enhancement — Myocardial fibrosis or scar detected by late gadolinium
enhancement (LGE, also known as delayed hyperenhancement) of trabeculae has been
observed in some patients with LVNC and may have prognostic value .
LGE distribution in patients fulfilling LVNC criteria can be very heterogeneous, which suggests
that there are several distinct cardiomyopathic processes responsible for LVNC .
A study in patients with LVNC found that diffuse fibrosis reflected by T1 mapping on CMR was
associated with ventricular arrhythmias and myocardial dysfunction .
The potential prognostic value of LGE is discussed separately.

32. RV involvement
The presence of noncompaction of the right ventricular (RV) myocardium is often difficult to
confirm by imaging.
A CMR study found that LVNC is associated with increased trabeculations of the RV apex and that
RV dysfunction in an LVNC population is associated with adverse clinical events .
The same impact on prognosis of LVNC in patients with RV involvement was shown by
echocardiography

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