Multidisciplinary Diagnostic Approach for Left Ventricular Hypertrabeculation/Noncompaction

The report on three patients with asymptomatic left ventricular hypertrabeculation/noncompaction (LVHT) by Koh et al.1 is stimulating but also raised the following concerns.

In light of recent reports about patients in whom LVHT developed during their lifetimes,2, 3 we regard discussing LVHT as a "congenital form of cardiomyopathy"1 as unjustified. Though LVHT appears to be congenital in the majority of cases, particularly in cases involving children and young adults, it is verifiably acquired in single cases.2, 3 Unfortunately, the pathomechanism of LVHT has neither been discovered for the acquired nor the congenital form. The most frequently presumed and discussed pathomechanisms for acquired LVHT are: (1) it is a compensatory mechanism of an impaired myocardium or (2) it results from destruction of the impaired myocardium by the intra-ventricular pressure. Congenital LVHT is most frequently attributed to an arrest of the physiologic intrauterine compaction process during embryonic heart development.

Since long-term follow-up data about the diagnosis of LVHT are lacking, it is speculative to state that LVHT is associated with increased morbidity and mortality in the patients described by Koh et al.

Since it is under debate if LVHT is an indication for oral anti-coagulation, we propose oral anti-coagulation only if decreased systolic function or atrial fibrillation is also present. This approach is substantiated by findings from a series of 62 patients of which thrombo-embolic events were found in only 10% of the patients with LVHT but in 15% of age-, sex- and left ventricular function-matched controls.4

LVHT is frequently found in patients with neuromuscular disorders. LVHT has been reported in association with Duchenne or Becker muscular dystrophy, myotonic dystrophy type 1, dystrobrevinopathy, Pompe's disease, myoadenylate-deaminase deficiency, mitochondriopathy, cypher gene mutations, centronuclear myopathy, Friedreich ataxia, Barth syndrome, or various other rare genetic disorders.5-10

Since atrio-ventricular block is a common feature of neuromuscular disorders with cardiac involvement, particularly in myotonic dystrophy, it appears essential to investigate each patient neurologically with appropriate examinations to exclude neuromuscular disorders as the underlying cause of LVHT.

It is stated that LVHT is an "extremely rare disorder".1 However, in our experience LVHT is more prevalent than previously thought particularly if asymptomatic relatives of patients with proven LVHT also undergo cardiac examinations. In an adult echocardiographic laboratory the prevalence of LVHT amounted to 0.25%/year.11 The true prevalence of LVHT among the general population is, however, unknown since no screening investigations have been carried out thus far.

Establishing the diagnosis of LVHT is dependent on the echocardiographer's awareness and experience, the applied transducer frequencies, and the applied diagnostic criteria. So far, three different definitions of LVHT have been proposed.5, 12, 13 Since there is no consensus about the accuracy and applicability of these definitions, it is desirable to know if LVHT in the described patients also fulfils diagnostic criteria other than the applied. Furthermore, we cannot understand how the ratio between a non-compacted and a compacted layer can be easily calculated at endsystole, particularly in small, well-contracting left ventricles.

Cardiac computed tomography represents a radiographic technique with a high radiation burden. An additionally supplied contrast medium is cost expensive. Cardiac MRI carries a much lower risk for side effects.

Extensive trabeculations found at autopsy in 68% of normal hearts refers to a number of up to three trabeculations. More than three trabeculations were found in only 4% of the normal hearts.14 The following anatomical findings were the bases for Stöllberger's LVHT definition: more than > 3 coarse, prominent trabeculations apically to the papillary muscles on echocardiography, which have the same echogenicity as the myocardium, move synchronously with it, are not connected to the papillary muscles, and are surrounded by intertrabecular spaces, which are perfused from the ventricular cavity.5

Finally, the diagnosis of a lumbar disc prolapse is questionable in a patient with bilateral radicular pain. Was there any indication for vertebral stenosis, discitis, or polyradiculitis? Did the patient's symptoms completely resolve after surgery?

In conclusion, LVHT is a rare cardiac abnormality of which the underlying etiology and pathomechanism are poorly understood. LVHT requires special attention not only of the cardiologist but also of the neurologist. Furthermore, special consideration is also required of the pediatrician in childhood and juvenile cases.