Left ventricular noncompaction has been estimated to occur most often in infants (0.81 per 100,000 infants/year), followed by children (0.12 cases per 100,000 children/year) (21), and adults (prevalence 0.014%).¹

The frequency of ventricular noncompaction among patients with established cardiomyopathy is 9.5% in children² and ranges from 3%³ to 16%⁴ in adults. In a clinical series of heart failure patients, ventricular noncompaction represented 3% of patients and 2% of all heart transplants.⁵

Left ventricular noncompaction may be an isolated finding or may be associated with other congenital heart anomalies (Table 159.1). When not associated with congenital heart disease, it can have dilated, hypertrophic, and restrictive phenotypes.⁶ A substantial proportion of children improve clinically, but most of these have recurrent deterioration of their ejection fraction at a median interval of 6.3 years.²

In adults, the noncompaction form of nonischemic cardiomyopathy occurs at a somewhat younger age than does idiopathic dilated cardiomyopathy (mean age at diagnosis: 39 years). The prognosis is similar.⁷

Acquired, diagnosed by cardiac imaging, has been described in highly trained athletes, patients with sickle cell anemia, and pregnant patients and can be reversible.¹

There have been rare reports with concomitant histiocytoid cardiomyopathy, suggesting a link with mitochondrial disease.^8,9

A proportion of cases of ventricular noncompaction are familial.^1,10 Mutations of several genes have been associated with LVNC. None is specific for the disease, and all have been reported in other phenotypes, most commonly dilated cardiomyopathy. Associated genes include ACTC1 (actin, alpha, cardiac muscle); DTNA (dystrobrevin alpha); LDB3 (domain-binding 3); MIB1 (homolog of Drosophila mind bomb); MYBPC3 (myosin-binding protein C, cardiac); MYH7 (β-myosin heavy chain 7, cardiac muscle); PRDM16 (PR domaincontaining protein 16); TAZ (tafazzin); TNNT2 (troponin T2); TPM1 (tropomyosin 1); and LMNA (lamin A).^1,6,11 The association with tafazzin mutations suggests a pathogenetic link between noncompaction and Barth syndrome. Approximately one-half of patients with Barth syndrome demonstrate imaging features of ventricular noncompaction (see Chapter).