Multidisciplinary Diagnostic Approach for Left Ventricular Hypertrabeculation/Noncompaction

Yonsei Med J Vol. 46, No. 2, 2005 The report on three patients with asymptomatic left ventricular hypertrabeculation/noncompaction (LVHT) by Koh et al. is stimulating but also raised the following concerns. In light of recent reports about patients in whom LVHT developed during their lifetimes, we regard discussing LVHT as a "congenital form of cardiomyopathy" 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. 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 anticoagulation 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-, sexand left ventricular functionmatched controls. 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. 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. 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 Multidisciplinary Diagnostic Approach for Left Ventricular Hypertrabeculation/Noncompaction