ISSN: 1885-5857 Impact factor 2023 7.2
Vol. 68. Num. 2.
Pages 167-168 (February 2015)

Letter to the editor
The Genetic Background of Left Ventricular Hypertrabeculation/Noncompaction Remains Vague. Response

El trasfondo genético de la hipertrabeculación/miocardiopatía no compactada ventricular izquierda sigue sin estar claro. Respuesta

María Rodríguez-SerranoabDiana DomingoabcBegoña IgualdEsther Zorioac
Rev Esp Cardiol. 2015;68:166-710.1016/j.rec.2014.09.010
Josef Finsterer, Sinda Zarrouk-Mahjoub

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To the Editor,

We appreciate the comments by Drs Finsterer and Zarrouk-Mahjoub.

These authors seem to question the genetic basis of left ventricular noncompaction (LVNC), contradicting the position of the European Society of Cardiology/American Heart Association (ESC/AHA).1–3 Although helpful, functional studies are not routinely performed. Instead, evidence in the literature, cosegregation, consequences in the protein and in silico studies are usually employed (as we did). Mutation carriers may not exhibit the phenotype because of an incomplete penetrance2 and diagnostic difficulties, such as different sets of criteria, suboptimal echocardiographic quality and reproducibility,3 and unavailable magnetic resonance imaging.

Is LVNC acquired? Can it disappear? These issues are unresolved2,4 and have not been addressed.

In silico studies are not the only data to assess a mutation. Additional information supported the pathogenic effect of ACTC1I289T (third paragraph, page 859). The genetic heterogeneity of LVNC is unquestionable.2,3

The preferred term is LVNC (PubMed) and the ESC considers “hypertrabeculation” to be incorrect.4 Even so, the above-mentioned authors prefer LVHT. We use LVNC if the criteria are fulfilled and hypertrabeculation (see the Figure in the paper by Rodríguez-Serrano et al.5) when these criteria cannot be assessed. Accordingly, hypertrabeculation for the heart explant (histologic criteria for LVNC are lacking) should also have been used within the text, but was changed for LVNC because of word count constraints.

Individuals II:4 and III:4 fullfilled the criteria of Chin and Stöllberger whereas individual III:6 did not.

The echocardiogram of patient IV:1, thoroughly reviewed, lacked LVNC. There were no histopathologic studies or stored pictures or tissues. Image acquisition limitations at the intensive care unit (small infant heart with an LV assist device) could explain the discrepancy but it is also possible that no discrepancy was actually present, the situation being a cardiomyopathy presenting with different phenotypes, namely restrictive cardiomyopathy in an infant (which can also be caused by ACTC1 mutations6) and LVNC in adults. Many circumstances may account for this phenomenon (age-dependent expression of modifier genes, additional mutations…).

Finally, neurological signs/symptoms and creatine kinase elevation were ruled out.

References
[1]
B.J. Maron, J.A. Towbin, G. Thiene, C. Antzelevitch, D. Corrado, D. Arnett, et al.
Contemporary definitions and classification of the cardiomyopathies: an American Heart Association Scientific Statement from the Council on Clinical Cardiology, Heart Failure and Transplantation Committee; Quality of Care and Outcomes Research and Functional Genomics and Translational Biology Interdisciplinary Working Groups; and Council on Epidemiology and Prevention.
[2]
C. Rapezzi, E. Arbustini, A.L. Caforio, P. Charron, J. Gimeno-Blanes, T. Heliö, et al.
Diagnostic work-up in cardiomyopathies: bridging the gap between clinical phenotypes and final diagnosis. A position statement from the ESC Working Group on Myocardial and Pericardial Diseases.
Eur Heart J., (2013), 34 pp. 1448-1458
[3]
P. Thavendiranathan, A. Dahiya, D. Phelan, M.Y. Desai, W.H. Tang.
Isolated left ventricular non-compaction controversies in diagnostic criteria, adverse outcomes and management.
[4]
E. Oechslin, R. Jenni.
Left ventricular non-compaction revisited: a distinct phenotype with genetic heterogeneity?.
Eur Heart J., (2011), 32 pp. 1446-1456
[5]
M. Rodríguez-Serrano, D. Domingo, B. Igual, A. Cano, P. Medina, E. Zorio.
Miocardiopatía no compactada familiar asociada con una mutación nueva en el gen de la alfa-actina cardiaca.
Rev Esp Cardiol., (2014), 67 pp. 857-859
[6]
J.P. Kaski, P. Syrris, M. Burch, M.T. Tomé-Esteban, M. Fenton, M. Christiansen, et al.
Idiopathic restrictive cardiomyopathy in children is caused by mutations in cardiac sarcomere protein genes.
Heart., (2008), 94 pp. 1478-1484
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