Noncompaction cardiomyopathy

Noncompaction cardiomyopathy

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]; Associate Editors-In-Chief: Cafer Zorkun, M.D., Ph.D. [3]

Overview

Non-compaction cardiomyopathy (NCC), sometimes known as "spongiform cardiomyopathy" is a rare congenital cardiomyopathy that affects both children and adults. It refers to a type of cardiomyopathy where the myocardial development is hindered during the early stages of fetal development (the embryogenesis stage). . It results from the failure of myocardial development during embryogenesis.

Pathophysiology

During development, the majority of the heart muscle is a sponge-like meshwork of interwoven myocardial fibers. As normal development progresses, these trabeculated structures undergo significant compaction that transforms them from spongy to solid. This process is particularly apparent in the [[ventricles of the heart|ventricles]], and particularly so in the left ventricle. Noncompaction cardiomyopathy results when there is failure of this process of compaction. Because the consequence of non-compaction is particularly evident in the left ventricle, the condition is also called left ventricular noncompaction. Other hypotheses and models have been proposed, none of which is as widely accepted as the noncompaction model.

This abnormality in development begins to occur around the 8 week mark during fetal development. The myocardium at this period of development is often referred to looking like a sponge as it is still a meshwork of interwoven myocardial fibers. This is beneficial at this stage as there is an increased surface area which allows perfusion of the myocardium from the left ventricular cavity. However as the embryo grows the myocardium should begin to be compact, in the case of NCC though the heart fails to fully compact leaving the myocardium to still have a spongy form. Non-compaction Cardiomyopathy can affect both ventricle walls of the heart separately or together however it generally only affects the left ventricle wall and therefore is sometimes known as left ventricular noncompaction.

Symptoms can range however are often a result of a poor pumping performance by the heart. The disease can be associated with other problems with the heart and other organs.

Noncompaction of ventricular myocardium was recently included in the 2006 classification of cardiomyopathies as a genetic cardiomyopathy .

Epidemiology

Due to its recent discovery as a diagnostic entity and the fact that has been unclassified as a cardiomyopathy according to the WHO, the incidence of the condition is not well characterized. Some reports suggest an incidence of approximately 0.12 cases per 100,000. This number may be an underestimation of the true percentage, as it only represents those patients with severe symptoms that have come to medical attention.

Diagnosis

Symptoms

Subjects symptoms from non-compaction cardiomyopathy range widely. It is possible to be diagnosed with the condition, yet not to suffer from any of the symptoms associated with heart disease . Likewise it possible to suffer from severe heart failure , which even though the condition is present from birth, may only manifest itself later in life.

• Shortness of breath and dyspnea on exertion (DOE)
• Fatigue
• Pedal edema or swelling of the ankles
• Limited physical capacity and exercise intolerance

Echocardiography

The ratio of compacted to non-compacted myoacardium may very at various developmental stages and ages. Non-compaction cardiomyopathy is characterized anatomically by deep trabeculations in the ventricular wall, which define recesses communicating with the main ventricular chamber. Major clinical correlates include systolic and diastolic dysfunction, associated at times with systemic embolic events. On echocardiography the left ventricular wall is thick with a two layered appearance. The epicardial layer is compacted and thin and the endocardial layer is non-compacted and thick. The ratio of the non-compacted endocardial layer to the epicardial layer is > 2.

Misdiagnosis

In a recent study of 53 patients with non-compaction cardiomyopathy, the first 42 were misdiagnosed with another form of heart disease. Improved awareness and improved imaging modalities allowed the correct diagnosis to be made in the last 11 cases. The most common misdiagnoses included:

• Dilated cardiomyopathy: 30 Cases
• Congenital heart disease: 6 Cases
• Ischemic heart disease: 2 Cases
• Disease of the heart valves: 2 Cases
• Dilated phase hypertensive cardiomyopathy: 1 Case
• Restrictive cardiomyopathy: 1 Case

The high number of misdiagnosis can be attributed due to non-compaction cardiomyopathy only being first reported in 1990, and so diagnosis is often overlooked or delayed. Advances in medical imaging equipment (Echo and MRI) has made it easier to diagnosis NCC.

Complications of NCC

The presence of NCC can also lead to other complications around the heart and in other organs. These are not necessarily common complications and no paper has yet to document the incidence of these complicationcs.

• Heart Related
  • Abnormalities of the origin of the left coronary artery
  • Pulmonary atresia
  • Stenosis
  • Right or Left ventricle obstruction
  • Hypoplastic left ventricle
  • Mitral regurgitation
  • Tachyarrhythmias and sudden cardiac death
  • Thrombus in the left ventricle

• Neuromuscular (Pertaining to both nerves and muscles)
  • Becker's muscular dystrophy
  • Mitochondrial myopathy
  • Polyneuropathy and metabolic myopathy

• Genetic related
  • Emery-Dreifuss muscular dystrophy
  • Myotubular cardiomyopathy
  • Barth syndrome

Prognosis

Due to non-compaction cardiomyopathy being a relatively new disease in terms of understanding it's impact on the human life expectancy is not very well understood. In a 2005 study which documented the long term follow up of 34 patients with NCC, 35% had died at the age of 42 +/- 40 months with a further 12% having to under go a heart transplant due to heart failure. However, this study was based upon symptomatic patients referred to a tertiary care center, and so were suffering from more severe forms of NCC than might be found typically in the population. As NCC is a genetic disease, as a precaution immediate family members are being tested which is turning up more supposedly healthy people with NCC who are not suffering from it. The long term prognosis for these people is currently unknown.

Management

The management of NCC is similar to that of other cardiomyopathies and includes the use of ACE inhibitors, beta blockers and aspirin. Implantation of an automatic internal cardiac defibrillator AICD may be appropriate in patients who are deemed to be at increased risk of sudden cardiac death. A small study from the Netherlands identified young females with premature ventricular contractions (PVCs) at risk of sudden death.

In severe NCC cases, in which severe heart failure has developed, a heart transplant may be necessary.

Source

• "Left Ventriuclar noncompaction" (PDF). Orphanet.

See also

Barth syndrome, Emery-Dreifuss muscular dystrophy, myotubular myopathy, genes responsible for NCC are located also in the area that cause these conditions.

Additional Resources

• "Left Ventricular Non-compaction". Baylor College of Medicine.
• "Contemporary Definitions and Classification of the Cardiomyopathies". American Heart Association Scientific Statement.
• "The Failing Heart". Nature.
• "Noncompaction of the left ventricle: a new cardiomyopathy is presented to the clinician". Sao Paulo Medical Journal.
• "Non-compaction of the Left Ventricular Myocardium - From Clinical Observation to the Discovery of a New Disease". Touch Cardiology.

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