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.