Noncompaction cardiomyopathy (NCC) is a congenital cardiomyopathy which is characterized by a spongy structure of the heart muscle (myocardium), which is the reason it is also called spongiform cardiomyopathy. This condition affects both children and adults. Symptoms can include shortness of breath, exercise intolerance, and reduced ejection fraction (EF). Patients with Non Compaction are considered to be at a greater risk for developing blood clots due to the blood retained in the heart. Noncompaction cardiomyopathy is a congenital pathological entity that can occur in isolated form or associated with other heart disease and often involves both ventricles. Noncompaction ventricular myocardium involves only left ventricle in 62% of the patients and both ventricles in 38%. The mean ratio of noncompacted to compacted myocardial layers at the site of maximal wall thickness was 3.4 ± 0.87 mm (range 2.2–7.5).
During fetal development, the majority of the heart muscle is a sponge-like meshwork of interwoven myocardial fibers. This is important for the nutrition of its cells. The spongy-like heart muscle is supplied predominately by diffusion of blood in the heart that flows into the spaces between the muscle bands. Later and simultaneously with the development of the coronary arteries, which will eventually take over carrying blood to the heart muscle, development of the muscle bands appears to go backwards. As normal development progresses, these trabeculated spongy structures undergo significant compaction that transforms them from spongy to solid. This process is particularly apparent in the ventricles, and particularly so in the left ventricle. Noncompaction cardiomyopathy results when there is failure of this process of compaction. Thus, in noncompaction cardiomyopathy, the growth of portions of the heart are arrested during pregnancy. Portions of the heart remain spongy and have mesh like fibers because they fail to become compact. The healthy portion of the heart becomes overworked and enlarged. This congenital heart defect may occur as a singular defect or may be accompanied by other congenital defects. There may be a family history of noncompaction cardiomyopathy or it may occur spontaneously.
Noncompaction has typically been associated with a high mortality rate but that outlook is beginning to change. With more advanced technology in echocardiogram and MRI as well as a heightened awareness of this particular type of cardiomyopathy more and more cases are being diagnosed early and correctly. Many studies have shown that patients with NCC (LVNC) have an increased risk of sudden cardiac death due to ventricular fibrillation even if the patient has no documented arrythmia. Patients may receive implantation of an ICD (implantable cardioverter-defibrillator) to prevent sudden cardiac death.