Isolated Left Ventricular Noncompaction: an underestimated cardiomyopathy?

Abstract

Isolated Left Ventricular Noncompaction (IVNC) is a rare congenital unclassified cardiomyopathy. This disorder, become widely known in the last 10 years, is postulated to be caused by intrauterine arrest of compaction of the myocardial fibres and meshwork, an important process in myocardial development. The predominant clinical features are heart failure, arrhythmias, embolic events and unexpected death (Jenni R et al., 2001) [1]. By definition, IVNC occurs in the absence of other structural heart disease. According to the new American Hearth Association classification of the cardiomyopathies, IVNC is classified as a primary, genetic cardiomiopathy but in the position statement of the European Society of Cardiology it is not yet considered as a distinct pathology (Elliott P et al., 2008) [2]. There is evidence that IVNC is a genetically heterogeneous disease. Using linkage and mutation analysis, a point mutation in the G4.5 gene has been identified in a family with X-linked infantile IVNC and in other forms of infantile X-linked dilated cardiomyopathies. Sabine Sasse-Klaassen et al., (2004) suggest an autosomal dominant mode of transmission of this disorder in adult subjects that seems to be distinct from paediatric form. A genome-wide linkage analysis of a family with autosomal dominant IVNC showed a gene locus that maps to human chromosome 11p15 (Sabine Sasse-Klaassen et al., 2004) [3]. Nevertheless, a major genetic cause for familial IVNC remains to be identified. The true prevalence of IVNC as a cause of heart failure and heart transplantation is unknown. In a recent study of primary cardiomyopathy in Australian children, IVNC was the third most common cardiomyopathy after dilated cardiomyopathy and hypertrophic cardiomyopathy and in another single center, IVNC was responsible for 9,5% of cardiomyopathies in children (Pignatelli RH et al., 2003) [4]. Recently, Kovacevic-Preradovic’s group in a retrospective study of 960 patients seen in the heart failure clinic from 1987 to 2005, describe the IVNC as a cause of heart failure common to hypertrophic cardiomyopathy, present in 2,7% of patients.