(See also Overview of Arrhythmogenic Cardiomyopathies Overview of Arrhythmogenic Cardiomyopathies Although any dilated or hypertrophic cardiomyopathy (see Overview of Cardiomyopathies) can produce cardiac and systemic factors that predispose to a number of different arrhythmias, including... read more and Overview of Arrhythmias Overview of Arrhythmias The normal heart beats in a regular, coordinated way because electrical impulses generated and spread by myocytes with unique electrical properties trigger a sequence of organized myocardial... read more 
)
Non-compaction cardiomyopathy is a rare (1 in 7000) cardiomyopathy resulting from failure of the embryonic ventricular myocardial compaction process, such that the ventricular myocardium consists of an outer layer of normally compact myocardium and an inner non-compacted layer that has retained embryonal characteristics. The inner layer is spongy and markedly trabeculated with deep intertrabecular recesses usually most prominent at the left ventricular apex, then elsewhere in the left ventricle, and least commonly in the right ventricle. Although there are likely acquired cases, most cases result from inherited mutations in genes encoding sarcomeric proteins, cytoskeletal proteins, or mitochondrial proteins. Inherited cases are most commonly autosomal dominant or X-linked.
In non-compaction cardiomyopathy, the disordered myocardial architecture and associated microvascular abnormalities lead to myocardial fibrosis. The fibrosis predisposes to both systolic and diastolic heart failure Heart Failure (HF) Heart failure (HF) is a syndrome of ventricular dysfunction. Left ventricular (LV) failure causes shortness of breath and fatigue, and right ventricular (RV) failure causes peripheral and abdominal... read more 
and to ventricular tachyarrhythmias, cardiac arrest, and sudden death. The deep intertrabecular recesses produce areas of blood flow stasis predisposing to thromboembolic events, including stroke Overview of Stroke Strokes are a heterogeneous group of disorders involving sudden, focal interruption of cerebral blood flow that causes neurologic deficit. Strokes can be Ischemic (80%), typically resulting... read more 
. Some forms also are associated with atrial tachyarrhythmias (eg, atrial fibrillation Atrial Fibrillation Atrial fibrillation is a rapid, irregularly irregular atrial rhythm. Symptoms include palpitations and sometimes weakness, effort intolerance, dyspnea, and presyncope. Atrial thrombi may form... read more , Wolff-Parkinson-White syndrome Wolff-Parkinson-White (WPW) syndrome Reentrant supraventricular tachycardias (SVT) involve reentrant pathways with a component above the bifurcation of the His bundle. Patients have sudden episodes of palpitations that begin and... read more ), conduction system blocks, early repolarization, long QT interval syndrome Long QT Interval Syndromes The long QT interval syndromes (LQTS) result from any congenital or acquired disorder of cardiac ion channel function or regulation (channelopathy) that prolongs ventricular myocyte action potential... read more , other congenital heart disorders Overview of Congenital Cardiovascular Anomalies Congenital heart disease is the most common congenital anomaly, occurring in almost 1% of live births ( 1). Among birth defects, congenital heart disease is the leading cause of infant mortality... read more 
, or skeletal muscular dystrophies Introduction to Inherited Muscular Disorders Muscular dystrophies are inherited, progressive muscle disorders resulting from defects in one or more genes needed for normal muscle structure and function; dystrophic changes (eg, muscle fiber... read more .
Patients may be asymptomatic. Initial symptoms are usually those of heart failure (eg, exertional dyspnea, fatigue, peripheral edema) although some patients present with symptoms of heart blocks and/or arrhythmias, including palpitations and/or syncope, or sometimes cardiac arrest. Ventricular tachyarrhythmias may be triggered by exercise.
Diagnosis of Non-Compaction Cardiomyopathy
Cardiac imaging (eg, echocardiography, magnetic resonance imaging with late gadolinium enhancement)
Genetic testing
Screening of first-degree relatives
Diagnosis of non-compaction cardiomyopathy is suspected in patients with manifestations of arrhythmias or conduction disorders in whom standard evaluation (eg, echocardiography) discloses ventricular wall abnormalities including hypertrophy, distinct layers, and deep trabeculae. However, it is frequently difficult to distinguish the findings in non-compaction cardiomyopathy from normal variations, particularly in patients with physiological or pathological left ventricular hypertrophy. Cardiac MRI with late gadolinium enhancement may be helpful.
Each imaging technique uses measurement cutoff criteria to enhance discrimination. Several different consensus criteria (eg, Jenni, Chin— 1 Diagnosis reference Non-compaction cardiomyopathy is a congenital disorder of the myocardium causing cardiomyopathy, a variety of arrhythmias, conduction disorders, and increased risk of sudden death. Diagnosis... read more ) have been developed to facilitate diagnosis. Patients with significant levels of myocardial fibrosis have a worse prognosis.
ECG and ambulatory cardiac rhythm monitoring are done to assess current rhythm status and are repeated annually to guide antiarrhythmic drug or device therapies.
Patients with findings suggestive of the disorder should have genetic testing.
First-degree family members of patients should have clinical evaluation (ie, to detect symptoms suggestive of arrhythmia, and/or heart failure), ECG, and echocardiography initially and repeated every 1 to 3 years. Genetic testing is done if the index case has a mutation identified. Family members who are not carriers of that mutation do not require ongoing testing.
Diagnosis reference
1. Jenni R, Oechslin E, Schneider J, et al: Echocardiographic and pathoanatomical characteristics of isolated left ventricular non-compaction: a step towards classification as a distinct cardiomyopathy. Heart 86(6):666–671, 2001. doi: 10.1136/heart.86.6.666
Treatment of Non-Compaction Cardiomyopathy
Moderation of physical activity
Sometimes an implantable cardioverter-defibrillator (ICD)
Usually a beta-blocker
Sometimes other antiarrhythmic drugs (particularly sotalol or amiodarone)
Heart failure therapy (including transplantation) as required
Sometimes chronic anticoagulation
Patients with non-compaction cardiomyopathy should avoid athletic exertion because such activities foster life-threatening arrhythmias.
Prevention of sudden death is by an ICD (see also Table Indications for an ICD Indications for Implantable Cardioverter-Defibrillators in Ventricular Tachycardia and Ventricular Fibrillation 
. An ICD is recommended for patients with prior sustained VT or resuscitated cardiac arrest or severe left ventricular systolic dysfunction.
A Heart Rhythm Society consensus statement (1 Treatment reference Non-compaction cardiomyopathy is a congenital disorder of the myocardium causing cardiomyopathy, a variety of arrhythmias, conduction disorders, and increased risk of sudden death. Diagnosis... read more ) indicates an ICD also may be useful (class IIa recommendations) in patients with non-compaction cardiomyopathy who have both nonsustained VT and reduced left ventricular ejection fraction.
Beta-blockers and other antiarrhythmic drugs are used to treat tachyarrhythmias as they occur.
Anticoagulation is used for patients with atrial fibrillation or stroke who meet standard criteria (see also CHA2DS2-VASc Score CHA2DS2-VASc Score ), although some authorities recommend anticoagulation for all patients with non-compaction cardiomyopathy and atrial fibrillation and/or trabecular thrombi regardless of their CHA2DS2-VASc Score.
Standard measures for treatment of heart failure are used as required (see also Treatment of Dilated Cardiomyopathy Treatment Dilated cardiomyopathy is myocardial dysfunction causing heart failure in which ventricular dilation and systolic dysfunction predominate. Symptoms include dyspnea, fatigue, and peripheral edema... read more 
).
Treatment reference
1. Towbin, JA, McKenna WJ, Abrams DJ, et al: 2019 HRS expert consensus statement on evaluation, risk stratification, and management of arrhythmogenic cardiomyopathy. Heart Rhythm 16:e301–e372, 2019. doi: 10.1016/j.hrthm.2019.05.007
Key Points
Non-compaction cardiomyopathies are genetic cardiac disorders that cause heart failure, arrhythmias, heart blocks, and thromboembolic disease.
Diagnosis is based on clinical factors, arrhythmias, cardiac imaging, and genetic testing.
First-degree family members have a significant risk of disease and require screening.
Treatment may require an implantable cardioverter-defibrillator (ICD), antiarrhythmic drugs, anticoagulation, and/or heart failure drugs.
Drugs Mentioned In This Article
| Drug Name | Select Trade |
|---|---|
sotalol |
BETAPACE, BETAPACE AF, Sorine , SOTYLIZE |
amiodarone |
Cordarone, Nexterone, Pacerone |
