Discussion
The diagnosis of LVNC is usually stablished by identifying the
morphologic diagnostic criteria proposed by Jenni et al. on
transthoracic echocardiography, which are the most validated and
commonly used 12. Those include: 1) Absence of
coexisting cardiac abnormalities (by definition); 2) A two-layer
structure with a compacted thin epicardial band and a much thicker
non-compacted endocardial layer of trabecular meshwork with deep
endomyocardial spaces. A maximal end systolic ratio of non-compacted to
compacted layers of > 2; 3) A predominant localization of
the affected segments at the mid-lateral, mid-inferior and apical areas.
Concomitant regional hypokinesia was not confined to the non-compacted
segments; 4) Colour Doppler evidence of deep perfused intertrabecular
recesses; 5) a Compacted wall thickness under or equal to 8.1mm13-15.
Despite this, sometimes the echocardiographic findings are not
diagnostic or are inconclusive as occurred in our patient, and a CMR
should be performed to confirm the diagnosis. Anyway, the CMR criteria
for diagnosis of LVNC differ slightly from the echocardiographic
criteria, since an end-diastolic noncompacted to compacted ratio
> 2.3 measured in the CMR at basal, mid and apical segments
has been considered the cutoff and the most accurate morphologic
criteria for LVNC diagnosis 3, 16-18. The CMR criteria
was fulfilled in our case with an end-diastolic non compacted to
compacted ratio > 3.
Although LVNC could be associated with other cardiomyopathies and
congenital cardiac defects 19-24, it also could be
found in highly trained athletes, patients with sickle cell anemia and
pregnants 25-28. However, as we described in our
patient, LVNC could be seen in the absence of these anomalies and is
referred as isolated LVNC.
LVNC cardiomyopathy complications include ventricular and atrial
arrhythmias, sudden death, systemic embolism and also heart failure
which is the most frequently complication described among several series
in children and adults 8 - 11. Abnormal
electrocardiographic findings related but not specific to LVNC are left
or right bundle brunch blocks, fascicular blocks, repolarization
abnormalities such as T-Wave inversion and ST-Segment changes
high-degree atrioventricular block, AF, atrial flutter, VT and
Wolff-Parkinson-White syndrome mainly in children8-11.
Frequent PVCs symptoms-related as a first manifestation of LVNC are very
unusual 8-11. Potentially, non-compaction itself may
represent a proarrhythmogenic substrate and therefore, several
mechanisms have been proposed to explain this including: concurrent
development of arrest of the conduction system, intertrabecular crypts
creating pathways for reentrant circuits, and ischemia from epicardial
coronary hypoperfusion of trabeculations 28.
Up to date, there is no specific guidelines for management of LVNC. Its
diagnosis requires to rule-out differential diagnoses as prominent
hypertrabeculation with normal compacted LV layer, hypertrophic or
dilated cardiomyopathy, endocardial fibroelastosis and LV apical
thrombus among others. Its management should include clinical monitoring
for asymptomatic patients with normal LV size and function or clinical
guidance according to current therapeutic evidence in symptomatic
patients due to LV dysfunction and/or arrythmias. Genetic testing for
LVNC is not always available and it should not change the clinical
management of the disease, but it may be useful for LVNC diagnosis
screening in patient´s relatives 3.