Left Ventricular Noncompaction

Abstract

BackgroundThere is considerable overlap between left ventricular noncompaction (LVNC) and other cardiomyopathies. LVNC has been reported in up to 40% of the general population, raising questions about whether it is a distinct pathological entity, a remodeling epiphenomenon, or merely an anatomical phenotype.ObjectivesThe authors determined the prevalence and predictors of LVNC in a healthy population using 4 cardiac magnetic resonance imaging diagnostic criteria.MethodsVolunteers >40 years of age (N = 1,651) with no history of cardiovascular disease (CVD), a 10-year risk of CVD < 20%, and a B-type natriuretic peptide level greater than their gender-specific median underwent magnetic resonance imaging scan as part of the TASCFORCE (Tayside Screening for Cardiac Events) study. LVNC ratios were measured on the horizontal and vertical long axis cine sequences. All individuals with a noncompaction ratio of ≥2 underwent short axis systolic and diastolic LVNC ratio measurements, and quantification of noncompacted and compacted myocardial mass ratios. Those who met all 4 criteria were considered to have LVNC.ResultsOf 1,480 participants analyzed, 219 (14.8%) met ≥1 diagnostic criterion for LVNC, 117 (7.9%) met 2 criteria, 63 (4.3%) met 3 criteria, and 19 (1.3%) met all 4 diagnostic criteria. There was no difference in demographic or allometric measures between those with and without LVNC. Long axis noncompaction ratios were the least specific, with current diagnostic criteria positive in 219 (14.8%), whereas the noncompacted to compacted myocardial mass ratio was the most specific, only being met in 61 (4.4%).ConclusionsA significant proportion of an asymptomatic population free from CVD satisfy all currently used cardiac magnetic resonance imaging diagnostic criteria for LVNC, suggesting that those criteria have poor specificity for LVNC, or that LVNC is an anatomical phenotype rather than a distinct cardiomyopathy.

Novel Genetic Triggers and Genotype–Phenotype Correlations in Patients With Left Ventricular Noncompaction

“…We also recognize that the LVNC phenotype may be secondary to causes other than genetic triggers, for example unfavorable LV remodeling. 7,45 With this in mind, we recognize that our study does not have longitudinal data and that we cannot document presence or absence of LV trabeculations early in life in our cohort. Although numerous potentially contributory mutations were identified using strict criteria (population conservation, evolutionary conservation and known deleteriousness of the variant, gene function), these variants may still not be disease causing.…”

“…There is an ongoing debate about whether LVNC can be labeled as a distinct cardiomyopathy or simply as a trait shared by other primary cardiomyopathies. 3-7 The American Heart Association classified LVNC as a distinct primary cardiomyopathy. 8 However, the European Society of Cardiology has designated LVNC as an “unclassified cardiomyopathy” and does not take a firm stance on whether LVNC is a separate cardiomyopathy or a morphological trait.…”

Role of Cardiac Magnetic Resonance in the Diagnosis and Prognosis of Nonischemic Cardiomyopathy

“…However, when using these criteria, up to 43% of individuals who get CMR as part of screening studies such as the Multi-Ethnic Study of Atherosclerosis can meet imaging criteria (30). Similarly, another screening study showed that up to 14.8% of normal individuals met at least 1 diagnostic criterion for LVNC (31). Thus, clinical criteria of symptomatic HF or LV dysfunction on CMR likely need to be included to improve the specificity of diagnosis.…”

The highest mortality rates in childhood dilated cardiomyopathy occur during the first year after diagnosis

“…DCM has been associated with significant morbidity and mortality and has been reported to account for more than half of all cardiac transplants in children and adolescents 4, 5, 6, 7, 8. Left ventricular noncompaction cardiomyopathy (LVNC) is still referred to as an unclassified cardiomyopathy that may develop into dilated cardiomyopathy–the LVNC‐dilated phenotype 9, 10, 11, 12. Because LVNCs have several morphological and functional phenotypes, they are difficult to diagnose 10, 12.…”

“…Left ventricular noncompaction cardiomyopathy (LVNC) is still referred to as an unclassified cardiomyopathy that may develop into dilated cardiomyopathy–the LVNC‐dilated phenotype 9, 10, 11, 12. Because LVNCs have several morphological and functional phenotypes, they are difficult to diagnose 10, 12. For example, both the European Society of Cardiology Working Group on Myocardial and Pericardial Diseases and the World Health Organization (WHO) define LVNC as an unclassified cardiomyopathy, whereas the American Heart Association defines LVNC as a primary genetically determined cardiomyopathy, which reflects the embryonic structure of the human heart due to an arrest in the compaction process during the first trimester.…”