The Cardiomyopathies

Definition: Cardiomyopathy is a disease of the heart muscle (myocardium) causing structural and functional abnormalities, which does not result from coronary artery disease, hypertension, valvular disease, or congenital heart disease.
The term "ischemic cardiomyopathy" continues to be in use for left ventricular systolic dysfunction caused by myocardial scar and left ventricular remodelling after a myocardial infarction, although according to this definition it is not exactly a cardiomyopathy, but a secondary myocardial disease.
Most (but not all) cardiomyopathies are familial. Thus family screening is often mandatory to identify people with undiagnosed or subclinical disease. In familial cardiomyopathies the inheritance is most often autosomal dominant and less often X- linked recessive, or autosomal recessive.
Cardiomyopathies are a heterogeneous group of diseases. Recently the MOGES classification system has been adopted, which describes the morphological and functional (morphofunctional) phenotype (M), organ involvement (O), genetic inheritance pattern (G), etiology (E), functional status (S).
Another classification of cadiomyopathies includes primary cardiomyopathies characterized by disease involving predominantly the myocardium and secondary cardiomyopathies, i.e. myocardial disease associated with a known specific etiology.
Primary cardiomyopahies include: 
Cardiomyopathies of genetic etiology
Hypertrophic cardiomyopathy, arrhytmogenic right ventricular cardiomyopathy, myocardial non compaction, glycogen storage disease (such as Danon's disease), mitochondrial myopathies and genetic ion channel disorders (channelopathies such as Brugada syndrome, congenital long QT syndrome, congenital short QT syndrome, catecholaminergic polymorphic ventricular tachycardia).
Cardiomyopathies of mixed (genetic or acquired) etiology:
 This category includes dilated cardiomyopathy and restrictive cardiomyopathy
Acquired cardiomyopathies such as:
 inflammatory cardiomyopathy (caused by myocarditis), alcoholic cardiomyopathy, peripartum cardiomyopathy, tachycardiomyopathy (cardiomyopathy due to a persistent tachyarrhythmia), stress induced cardiomyopathy also known as Tako-tsubo cardiomyopathy

Hypertrophic cardiomyopathy (HCM) 
It is the most common inherited cardiac disorder with a prevalence in the general population of approximately 1 per 500. 

There is hypertrophy of left (usually), right, or both ventricles
preserved or reduced contractile function. Hypertrophy (increased cardiac muscle thickness) is inappropriate (is not expected as a result of an etiologic condition, such as hypertension, aortic stenosis, etc) may be generalized or regional and it almost always presents by the age of 30 years. Histologically HCM is characterised by left ventricular hypertrophy with malalignment of the myocardial fibres (myofibril disarray) and myocardial fibrosis. The hypertrophy may be generalised or confined largely to the interventricular septum (asymmetric septal hypertrophy) or other regions (e.g. apical hypertrophic cardiomyopathy).
Causes of HCM
HCM is a genetic disorder, caused by mutations of genes encoding proteins involved in the contractile apparatus of the myocardial cells.The most common mutation involves beta-myosin heavy chains. There are also other mutations involving troponin T, tropomyosin, and other proteins. The mode of genetic transmission is usually autosomal dominant, with a high degree of penetrance and variable expression.
Clinical presentation: most patients with HCM are asymptomatic, but some present with dyspnea, effort angina palpitations (due to arrhythmias), syncope, or sudden death. In summary, hypertrophic cardiomyopathy (HCM) can be asymptomatic or it can result in heart failure with preserved ejection fraction (EF), in sudden cardiac death, or rarely in heart failure with reduced EF.
 Heart failure with preserved ejection fraction (EF), usually manifested by effort dyspnea (breathlessness during physical activity) can occur in HCM, because myocardial hypertrophy can produce a stiff ventricle with reduced compliance. This results in an elevation of the diastolic filling pressure. 
Angina, when present, in HCM usually results from increased myocardial oxygen demand due to the hypertrophy.
In hypertrophic obstructive cardiomyopathy (HOCM), a form of HCM characterized by the presence of  dynamic left ventricular outflow tract (LVOT) obstruction, the systolic pressure gradient in the LVOT contributes to the development of symptoms.  In HOCM the dynamic LVOT obstruction is caused by the hypertrophy of the interventricular septum and the abnormal systolic anterior motion (SAM) of the mitral valve. SAM can also cause mitral regurgitation.
Physical examination in HCM can be normal , or reveal only a fourth (presystolic) heart sound S4, when there is no LVOT obstruction. The S4 is caused by LV diastolic dysfunction resulting in a forceful left atrial contraction against a stiff ventricle. The apical impulse is often forceful and diffuse. A double impulse can be present because of a presystolic impulse due to the forceful atrial contraction as a consequence of the reduced LV compliance.
In hypertrophic obstructive cardiomyopathy (HOCM) :
 >The carotid pulse typically rises sharply and then falls sharply in midsystole (because of the LVOT obstruction in midsystole) followed by a second rise
> There is a midsystolic crescendo-decresendo murmur best heard at the left sternal border and at the area between the apex and the left sternal border. This murmur of dynamic LVOT obstruction is accentuated by maneuvers that decrease preload (abruptly standing up, which reduces venous return to the heart) or decrease afterload (vasodilation by administering sublingual nitrate) and does not radiate to the neck. These features help distinguish the murmur of HOCM from the murmur of valvular aortic stenosis (also see chapter on aortic stenosis).
> A pansystolic murmur is often heard at the apex due to mitral regurgitation.
The ECG is abnormal in the majority of patients with hypertrophic cardiomyopathy (HCM). The commonest abnormalities are ST and T wave abnormalities followed by signs of left ventricular hypertrophy ( Tall R waves especially in mid-precordial leads and also in left precordial leads). Prominent  Q waves may be present in the inferior and/or precordial leads, caused by septal hypertrophy. Giant negative T waves in the precordial leads occur in apical HCM. 
The chest X ray may demonstrate a normal heart size or cardiac enlargement due to LV hypertrophy and left atrial dilatation. 
Echocardiography in HCM 
There are some characteristic features that strongly indicate HCM:
1) Hypertrophy of any segment of the LV with wall thickness > 1,5 cm.
2) Asymmetric septal hypertrophy (the interventricular septum is much thicker than other segments of LV wall) with a ratio of wall thickness septum/posterior wall > 1.3 in normotensive  and > 1.5 in hypertensive individuals. This is the commonest form of HCM.
3) In HOCM (a common type of HCM) : Asymmetric hypertrophy of the interventricular septum with SAM of the anterior mitral leaflet, increased velocity of flow in the left ventricular outflow tract (LVOT) and a systolic pressure gradient in the LVOT. The latter two findings are evidence of LV dynamic obstruction. Obstruction is dynamic, meaning that it changes at different times at the same patient and especially with changes in preload, afterload or contractility. Some patients have obstruction at rest, whereas others only during exercise.  Obstruction is present when the peak intraventricular systolic gradient is ≥ 30 mmHg. Severe obstuction is present when the peak gradient is > 50 mmHg.   Mitral regurgitation is often present. 
4) Concentric hypertrophy of the LV without any identifiable cause, especially with a wall thickness ≥ 1.5 cm.
5) Apical hypertrophy of the LV (this is a rare form of HCM, about 1 % of cases)
6) Mid-ventricular hypertrophy of the LV with signs of systolic obstruction at the level of the papillary muscles (such signs are a turbulent high velocity systolic flow at the midventricular level, demonstrated with color flow doppler and a systolic intraventricular gradient at this level, demonstrated with pulse wave spectral doppler.) The LV apex is usually aneurysmatic. This is a rare form of HCM.
7) In some cases of HCM hypertrophy of the right ventricle (RV) can also be present (RV wall thickness > 5 mm).
Differential diagnosis of HCM includes other causes of increased ventricular wall thickness: e.g. hypertensive heart disease, aortic stenosis, infiltrative and storage diseases (amyloidosis, Fabry disease).
Treatment of HCM
In patients without an LVOT gradient pharmacologic therapy is administered if there are symptoms (dyspnea or chest pain): Beta blockers (starting at a dose equivalent to propranolol 80-120 mg/day and titrated to achieve a heart rate of 50-70 beats per minute at rest ) or alernatively non dihydropyridine calcium  antagonists (verapamil starting at a dose of 120 mg/day, or diltiazem starting at a dose of 180 mg/day).

In patients with HOCM who have symptoms, treatment to reduce the LVOT gradient is indicated. Such treatment includes
beta-blockers, usually in high doses. If this fails, combined treatment with a beta blocker (in a small to moderate dose) plus disopyramide  (an antiarrhythmic drug with potent negative inotropic properties) is an option. Disopyramide is usually given at a dose of 400-600 mg/day and can often cause side effects due to its anticholinergic action (dry mouth and eyes, urinary retention).
Surgical myectomy, alcohol septal ablation or DDD pacing are treatment options (that act by reducing the LVOT gradient) selected in cases of HOCM with symptoms refractory to medical therapy, or who cannot tolerate medical therapy and a significant LVOT pressure gradient (i.e. a pressure gradient > 50 mmHg in the LVOT, in LV systole). DDD pacing generally is less effective than the other two treatments (surgery, or septal ablation). Both surgical myectomy and alcohol septal ablation are effective procedures, associated with low rates of complications and high success rates, when performed in centers with experience. There is debate regarding which procedure is best. Two basic concerns with percutaneous septal ablation are the following: There is a potential for creation of an arrhythmogenic focus (since the procedure causes a myocardial infarct at the proximal interventricular septum) and there is also an increased risk of complete heart block, as a procedural complication.
In summary, in HCM either with, or without intraventricular obstruction, treatment is needed in patients who have symptoms and not in asymptomatic people. Evaluation for risk factors for sudden cardiac death is needed in all patients. 

Important : Risk factors for sudden death in HCM  are as follows:
The most powerful, but also very obvious, risk factor is a personal history of resuscitated cardiac arrest, or sustained ventricular tachycardia. This is an indication for an implantable defibrillator (ICD). 
Massive left ventricular hypertrophy (>30 mm on echocardiography)
Family history of sudden cardiac death (that has occured before the age of 50 in one or more first degree relatives with or without a diagnosis of HCM, or sudden death in one or more first degree relatives irrespective of age, with an established diagnosis of HCM).
Non-sustained ventricular tachycardia on 24-hour Holter monitoring
Prior unexplained syncope
Abnormal blood pressure (BP) response on exercise (failure of BP to rise, or a fall in BP with exercise).
 ICD insertion should be seriously considered in patients with 2 or more of these risk factors.  When the risk is less, amiodarone is an appropriate alternative.

A VIDEO :  Hypertrophic Cardiomyopathy: The ECG, echocardiography and treatment

Dilated cardiomyopathy (DCM):
There is impaired systolic function and dilatation of one or both ventricles. It more often affects the left ventricle and then it  is characterized by left ventricular dilatation associated with decreased contractile function (left ventricular EF <45%) in the absence of coronary artery disease sufficient to cause global systolic dysfunction and in the absense of abnormal ventricular loading conditions (hypertension, valvular heart disease, congenital heart disease). DCM can result in heart failure with reduced ejection fraction (EF). Right ventricular dilation and dysfunction may also be present but are not necessary for the diagnosis.
Causes of DCM 
 The most common causes are idiopathic and inherited (familial DCM, due to genetic defects).
Idiopathic DCM includes cases with no clearly identified cause and is considered to result from an interplay of unclear familial, immune-mediated, toxic, or infectious mechanisms that ultimately result in myocardial systolic dysfunction. Some cases are due to a previous episode of subclinical viral myocarditis. Viral components present in the myocardial tissue may serve as antigens that can direct the immune system to attack the myocardium.
An abnormality of immune regulation may play a role in DCM, as suggested by the association of DCM with some HLA antigens (HLA DR4).
Familial DCM accounts for about 30-50 % of cases and is due to mutations of genes that result in myocardial dysfunction and reduced contractile force. Most cases of familial DCM demonstrate an autosomal dominant mode of inheritance, although autosomal recessive and X-linked forms also exist. They are the result of mutations of genes encoding cytoskeletal, contractile or nuclear membrane proteins (dystrophin, desmin, actin, troponin, a-tropomyosin, beta-myosin heavy chain, lamin, vinculin).  
Some neuromuscular diseases of genetic origin also cause DCM (Duchenne muscular dystrophy).

Other causes of DCM are due to myocardial inflammation and cell damage via infective, immunologic or toxic mechanisms.
Such causes are:
 Infections (viral myocarditis, Chagas disease)
Drugs and toxins (
Alcohol, cocaine, doxorubicin, cyclophosphamide,)
Peripartum cardiomyopathy
Systemic vasculitis (systemic lupus erythematosus)
Other causes of DCM include various systemic diseases such as: uremia, thyroid disease, pheochromocytoma, glycogen storage disease.
Whereas coronary artery disease (CAD) is the most common cause of left ventricular (LV) systolic dysfunction and dilatation, this condition (often called ischemic cardiomyopathy) is not classified as dilated cardiomyopathy.
Clinical presentation of DCM 
DCM usually presents with signs and symptoms of congestive heart failure. Thus the major presenting symptoms are effort dyspnea or paroxysmal nocturnal dyspnea, fatigue and effort intolerance and edema. Other presentations include systemic emboli (from LV wall thrombus), syncope, angina, cardiac arrhythmias, conduction defects  or sudden death (from ventricular arrhythmias). Chest pain, including typical angina, may be present in some patients with DCM (even though it is not considered one of the main symptoms) and should not be used as a proof of coronary artery disease as the etiology of myocardial systolic dysfunction. It may indicate a more limited coronary vascular reserve in these patients, despite normal epicardial coronary arteries.
Physical examination in DCM can show:
An apical impulse which is laterally displaced, because of left ventricular (LV) enlargement.
 A narrow pulse pressure (this is a sign of a diminished stroke volume)
Pulsus alternans (in cases of severe LV dysfunction).
In auscultation a fourth (presystolic) heart sound (S4) is common and in case of decompensated heart failure, there is often a third (early diastolic) heart sound -S3. Systolic murmurs of mitral or tricuspid regurgitation are also common, because dilated cardiomyopathy (DCM) is often associated with functional atrioventricular valve regurgitation.
The ECG in DCM often shows poor R wave progression (or even Q waves) in the precordial leads, because of myocardial fibrosis and P wave morphology indicative of left atrial dilatation. ST and T wave abnormalities frequently occur.
   Another common finding is an intraventricular conduction defect (for example a LBBB) causing an increased QRS duration. Atrial or ventricular arrhythmias are also common. 
The chest X ray usually demonstrates a generalized enlargement of the cardiac silhouette due to dilatation of the cardiac chambers (cardiomegaly= enlargement of the heart).
Echocardiography is valuable for the diagnosis, since it can assess ventricular size and function. Usually in DCM there is a diffuse reduction of LV contractility (hypokinesis) with LV dilation (often the best contracting LV segment is the basal posterior and /or the basal lateral). In ischemic cardiomyopathy diffuse hypokinesis  and LV dilatation can also be present, but there is akinesis and reduced thickness of the infarcted segments. This is a useful distinguishing feature between these two entities. 
In some cases of mild DCM, or at an early stage of the disease echocardiography can show a mild diffuse hypokinesis of the left ventricle (LV) without LV dilatation and with an ejection fraction (EF) being at the lower normal limits or mildly abnormal.
Ventricular size and function can also be  assessed very accurately with magnetic resonance imaging (MRI).
Cardiac catheterization and coronary angiography is often necessary to exclude coronary artery disease as the cause of the LV dysfunction. Usual hemodynamic findings in cardiac catheterization include an elevated left ventricular end-diastolic pressure and pulmonary capillary wedge pressure and often modest pulmonary hypertension. Left ventriculography demonstrates diffuse contractile dysfunction of a dilated LV.
Treatment of DCM
Standard treatment for heart failure with reduced EF (systolic heart failure) which usually includes an ACE inhibitor, a beta blocker, a diuretic (usually furosemide) and an aldosterone antagonist (MRA=mineralocorticoid receptor antagonist). Digoxin can be added if there is atrial fibrillation with a relatively rapid ventricular response, or in patients with sinus rhythm but persistent symptoms of heart failure despite the above standard treatment.
Regular exercise (as tolerated) is beneficial. 
Cardiac resynchronization, or an  ICD (implantable cardioverter defirilator) may be needed in patients with an indication (see chapter on heart failure for the indications).
For patients with end stage heart failure treatment options include ventricular assist devices and heart transplantation.
A case of DCM (left parasternal long axis view)

Restrictive cardiomyopathy (RCM)
Restrictive cardiomyopathy (RCM) is a rare type of cardiac muscle disease, in which symptoms and signs of congestive heart failure occur in a patient with normal or decreased volume of both ventricles and bi-atrial enlargement (dilatation of both atria). The ventricles have a normal or near normal systolic function as assessed visually with 2-dimensional imaging or with the ejection fraction, despite of the manifestations of heart failure. (More sensitive echocardiographic techniques such as tissue doppler or myocardial strain and strain rate show an impairment of the systolic function, that is not apparent on visual estimation with 2-dimensional imaging or M-mode measurements).  Ventricular wall thickness can be normal or increased (depending on the etiology) and cardiac valves have no significant dysfunction.
 It should be emphasized that the predominant abnormality in these patients is a severely impaired ventricular filling with restrictive physiology, which produces symptoms and signs of heart failure.
The restrictive physiology is caused by severely reduced compliance (elasticity) of the ventricular walls and can be demonstrated by doppler echocardiography, or cardiac catheterization.
Causes of RCM
The most common cause is amyloidosis.
Other causes: Sarcoidosis, hemochromatosis, Loeffler's endocarditis,  endomyocardial fibrosis,radiation, metastatic cancer, diabetic cardiomyopathy, systemic scleroderma, idiopathic restrictive cardiomyopathy (it can be familial). 
In Loeffler's endocarditis and endomyocardial fibrosis there is myocardial and endocardial fibrosis apparent in imaging tests (echocardiography or magnetic resonance imaging) and blood tests (complete blood count-CBC) show eosinophilia.
Investigations in RCM
 Chest X-ray may show pulmonary venous congestion. The cardiac silhouette can be normal or mildly enlarged (because of atrial enlargement).
The ECG may show low QRS voltage and nonspecific ST-segment and T-wave abnormalities.
 Echocardiogram demonstrates a normal or near-normal ejection fraction (EF), dilatation of both atria and impaired ventricular filling.
The severely impaired ventricular filling (restrictive physiology) is characterized by the following findings :
Significant dilatation of the atria
Mitral inflow pattern (obtained with the pulse wave doppler at the tips of the mitral valve) with
E wave peak velocity/ A wave peak velocity >1.5
(E wave is the early diastolic velocity of the blood moving through the mitral valve and A wave is the end-diastolic velocity at the time of atrial contraction-absent in atrial fibrillation). The deceleration time (DT) of the E wave (the time from peak velocity of blood flow to zero velocity) is reduced : DT ≤ 150 msec.
( Isovolumic relaxation time is also reduced: IVRT < 60 msec).
Pulse wave doppler examination of blood flow in a pulmonary vein (performed in the apical 4 chamber view) will show a marked predominance of the D wave (of early diastolic flow through the pulmonary veins) over the S wave (of systolic flow) with
peak S velocity/peak D velocity <0.5  The S and D waves are both positive waves (over the baseline) because they represent flow with direction into the left atrium and towards the tranducer (which is at the apex of the heart). The peak velocity of the AR wave (a negative wave of reverse flow from the atrium into the pulmonary vein at end-diastole during atrial systole, in sinus rhythm) is elevated 
(> 35 cm/s). 
Tissue doppler measurements of the velocity at the mitral annulus demonstrates reduced early diastolic peak velocity (E') : E'< 8 cm/s and E/E' > 15 (this indicates an elevated LV end diastolic pressure). In this ratio E=the peak velocity of early diastolic blood flow through the mitral valve and E'=the peak early diastolic velocity of the mitral annulus. The first is measured with pulse wave flow doppler through the tips of the mitral valve (in the apical 4 chamber view) and the latter with the pulse wave tissue doppler at the mitral annulus.
In contrast, in constrictive pericarditis peak velocity E' of the septal mitral annulus  > 8 cm/s. The differential diagnosis between restrictive cardiomyopathy and constritive pericarditis is a classic problem, because both conditions produce a clinical picture of heart failure caused by severe diastolic dysfunction.  Another difference between these two entities is the following. In constrictive pericarditis there is a marked respiratory variation (by more than 30%) of the peak E (early diastolic) blood flow velocity both in mitral and tricuspid flow, with mitral E velocity decreasing in inspiration and tricuspid E velocity increasing in inspiration. This is due to the phenomenon of the ventricular interdependence (for an explanation of this term see chapter on constrictive pericarditis). This phenomenon of ventricular interdependence does not exist in restrictive cardiomyopathy (RCM), therefore in RCM the respiratory variation in the trasmitral and transtricuspid flow is not augmented. In fact, in RCM respiratory variation in flow velocities through the atrioventricular valves is diminished or absent. 
Cardiac catheterization in RCM shows elevation of filling pressures (diastolic pressures) in both ventricles, and a dip-and-plateau ventricular diastolic pressure tracing (a pattern like the symbol of square root) is often seen. These are also features of contrictive pericarditis (CP). A difference is that in CP there is equalization of diastolic pressures of both ventricles (the difference of end-diastolic pressure between the two ventricles is <5 mmHg in CP). On the contrary, in RCM this difference is usually > 5mmHg.  Therefore, careful evaluation of simultaneously recorded LV and RV pressures helps in distinguishing between the two.

 A very useful parameter is the change in these simultaneously recorded ventricular pressures during respiration.
This in CP demonstrates discordant changes in systolic pressures with respiration 
(inspiratory increase in RV systolic pressure with a simultaneous decrease in LV systolic pressure/ the opposite in expiration). In contrast, in RCM the change in the systolic pressure of the RV and the LV with respiration is concordant ( they increase or diminish  concomitantly and their respiratory changes are small). 
Treatment of RCM
Diuretics are adminisered for heart failure symptoms, but cautiously (elevations in dosage must be cautious and gradual in order to relieve congestive symptoms, without reducing left ventricular filling pressures to the point of causing hypotension). Beta-blockers are commonly administered, especially if the heart rate is rapid but any reduction in heart rate should be moderate. These patients do not need a slow heart rate because diastolic filling occurs only at the beginning of diastole, so there is no point in increasing the duration of diastole. A slow heart rate in patients with RCM will usually decrease cardiac output and this results in worsening of symptoms. In patients with secondary restrictive cardiomyopathies, specific treatment of the underlying systemic disease is often indicated. In many cases referral for transplant assessment should be considered early because severe pulmonary hypertension may develop.

Video : A case of RCM due to cardiac amyloidosis 

Arrhythmogenic right ventricular cardiomyopathy (AVRC)
It is also known as arrhythmogenic right ventricular dysplasia. In this condition, inherited as an autosomal dominant trait, patches of the right ventricular myocardium are replaced with fibrous and fatty tissue. Fibrofatty replacement can also occur in the left ventricle. It has a prevalence of approximately 1 per 10000 to 1 per 5000 in the general adult population. The dominant clinical problems are ventricular arrhythmias (ventricular tachycardia-VT, monomorphic with an LBBB pattern, or polymorphic VT), syncope, sudden death and right-sided heart failure. Common presenting symptoms are palpitations and syncope. Sudden cardiac death due to fatal ventricular arrhythmias is also a common first manifestation (in over 20% of ARVC patients). Right ventricular or biventricular failure occurs in advanced stages of the disease, whereas sudden cardiac death can also occur at an early stage.
The ECG typically shows a slightly broadened QRS complex often with incomplete or complete RBBB  and inverted T waves in the right precordial leads (V1-V3, which are the leads related to the right ventricle). Aepsilon wave can be present i.e. a terminal notch of the QRS (a small wave at the end of the QRS), as a result of slowed intraventricular conduction in an area of the right ventricle. In some cases the ECG can be normal.  Holter monitoring may demonstrate frequent extrasystoles of right ventricular origin or runs of non-sustained ventricular tachycardia.
 Echocardiography is frequently normal at an early stage, but in more advanced cases it often demonstrates right ventricular dilatation and/or aneurysm of a segment of the RV wall. There may be left ventricular dilatation and dysfunction.
Treatment of ARVC 
Beta-blockers are first-line treatment for patients with non-life-threatening arrhythmias. Amiodarone or sotalol can be used for symptomatic arrhythmias. In cases of  life-threatening arrhythmias, or indications of high risk for sudden cardiac death an implanted cardioverter defibrillator (ICD) is required. Obviously, there is an indication for an ICD in patients who had a previous episode of cardiac arrest (aborted SCD) or of hemodynamically unstable sustained ventricular tachycardia (VT), but ICD implantation should also be seriously considered in patients with an episode of hemodynamically stable VT.
 Cardiac transplantation is indicated in some severe cases for end stage heart failure or for intractable arrhythmia. 
Clinical risk factors that predict an increased risk of sudden cardiac death (SCD) in patients with arrhythmogenic right ventricular cardiomyopathy are the following:
Hemodynamically stable sustained VT

Non-sustained VT
History of unexplained syncope
Severe dilatation and/or dysfunction of the right or the left ventricle, or both
Early onset  (age < 35 years) of severe structural disease (with prominent ventricular dilatation or dysfunction)
Left heart failure 
Family of history of SCD
An ICD is recommended for patients with ARVC for primary
prevention of SCD if such risk factors are present, as well as for secondary prevention of SCD (i.e. in patients who have been resuscitated and have survived an episode of cardiac arrest or sustained VT) regardless of risk factors.

Left ventricular non-compaction
Left ventricular non-compaction is a sponge-like appearance of an area of the left ventricle (LV). It results from an arrest of
myocardial maturation during embryogenesis. Familial and spontaneous cases have been described. In patients with LV non compaction mutations in several genes encoding proteins of the
cytoskeleton, sarcomere, and mitochondria have been implicated.  
The condition predominantly affects the apical segments of the LV and also the mid-inferior and mid-lateral wall. LV non-compaction can be isolated, or it may be associated with congenital heart abnormalities (such as an atrial or ventricular septum defect, or coarctation of the aorta).  
The condition is diagnosed by echocardiography, cardiac MRI (magnetic resonanse imaging) or left ventriculography (injection of contrast medium into the LV during cardiac catheterization). On these imaging studies, affected areas have a thick myocardium consisting of a thin compacted outer layer and a thicker noncompacted inner layer. The noncompacted myocardial layer has prominent trabeculations and deep endomyocardial recesses, that communicate with the left ventricular cavity.
 Useful diagnostic criteria are the following:
 The thickness of the noncompacted endocardial layer is > 2 times the thikness of the compacted epicardial layer at end systole.
The presence of blood flow should be demonstrated (with color flow doppler or contrast echocardiography) in the recesses between the myocardial trabeculations.
The presense of > 3 trabeculations visible in a single image, protruding from the left ventricular wall, apically to the papillary muscles, with intertrabecular spaces connected with the ventricular cavity.
Evidence of systolic and/or diastolic LV dysfunction should be present.
Cardiovascular magnetic resonance imaging (CMR)  permits an even better visualization of trabeculations and recesses of the LV myocardium, therefore it is a useful diagnostic test for LV non compaction.
The disease usually leads to the development of heart failure due to systolic and/or diastolic dysfunction. LV non-compaction, especially if it involves an extensive area of the myocardium, can result in congestive cardiac failure, thromboembolism, cardiac arrhythmias and sudden death. Manifestations can appear in adult age, or in childhood.
Treatment, when necessary, is for associated heart failure (the standard treatment for HF with reduced EF, see chapter on heart failure),  arrhythmias (beta blockers, amiodarone, or an ICD may be needed depending on the clinical scenario and according to their standard indications), and the risk of emboli (anticogulation may be needed). Regarding anticoagulation, one must take into account that patients with LV non compaction with or without atrial fibrillation
are at high risk for thromboembolism if they have impaired left ventricular systolic function. Therefore, anticoagulation with a vitamin K antagonist (warfarin, or acenocoumarol) is recommended in patients with LV non compaction,with
 left ventricular EF <40 %, even if they do not have a history of atrial fibrillation.

Takotsubo cardiomyopathy
Takotsubo cardiomyopathy is a syndrome of transient apical left ventricular dysfunction (which is apparent with echocardiography or left ventriculography) with a clinical picture that mimics a myocardial infarction (chest pain, or dyspnea, ST segment elevation, and raised cardiac biomarkers).
Important features of the syndrome are its assossiation with a period of emotional stress, normal epicardial coronary arteries (demonstrated with coronary angiography), and characteristic akinesia of the apical and occasionally also the mid- segments of the LV on echocardiography or ventriculography with good contractile function of the basal segments.
Possible mechanisms include a hyperadrenergic syndrome (i.e. the effects of increased levels of catecholamines), or coronary artery spasm.
Complete recovery of myocardial systolic function usually occurs within 4–6 weeks, but recurrences can occur.

Peripartum cardiomyopathy
This is a rare condition that occurs in the last trimester of pregnancy or within 5 months of delivery and presents clinically and echocardiographically as a dilated cardiomyopathy with left ventricular systolic dysfunction. This diagnosis is made, when no other cause of LV dysfunction is found.  It is more common in  multiparous, obese women over 30 years old.
Recovery to normal ventricular systolic function within 6 months occurs in nearly half of the cases, but in some patients peripartum cardiomyopathy can demonstrate a severe course with progressive heart failure, or it can cause sudden death.

Treatment of peripartum cardiomyopathy, as is the case for every cardiomyopathy of the dilated type, must be in accordance with heart failure guidelines, which include a medical regimen of: angiotensin-converting enzyme inhibitors (or angiotensin receptor-blockers), beta-blockers, diuretics and mineralocorticoid receptor antagonists (MRAs). 
 In patients who present with acute peripartum cardiomyopathy, studies have reported a beneficial effect of bromocriptine (a prolactin-blocker). Bromocriptine is currently being evaluated in larger studies to assess its cardiovasular effects.
In peripartum cardiomyopathy, standard heart failure therapy should be continued for a minimum of 12 months after the time of diagnosis. If cardiac function recovers, cardiac dysfunction can re-emerge if patients are to get pregnant again, therefore, they should be advised on contraceptive measures (Patients should be advised to avoid a future pregnancy). 

Tachycardia induced cardiomyopathy
This is a rare form of dilated cardiomyopathy caused by prolonged periods of supraventricular or ventricular tachycardia, which is peristent or very frequent, in order to cause LV systolic dysfunction.

Appart from tachycardia duration, another significant factor that contributes to the development of ventricular dysfunction is the ventricular rate. Patients with higher ventricular rates develop cardiomyopathy earlier.
A clinical problem is determining if the tachycardia is the cause of the cardiomyopathy or if  the arrhythmia is a consequence of a cardiomyopathy of different etiology.  Tachycardia induced cardiomyopathy should be suspected in every patient with LV dysfunction in the setting of a persistent tachyarrhythmia, when another cause for the LV dysfunction cannot be found.
Tachycardia induced cardiomyopathy is generally reversible once the underlying arrhythmia is controlled, therefore it is important to  treat promptly the tachycardia responsible for the condition.
Successful treatment of the causative prolonged arrhythmia, usually results in recovery of cardiac function. Usually the greatest recovery of the LV ejection fraction (EF) is observed approximately 1 month after arrhythmia cessation and a more gradual recovery, which may lead to a complete normalisation in many cases, can be observed up to one year thereafter.
 Heart rate normalisation, either with rate or rhythm control, is the cornerstone of management. Most of the data available come from patients with atrial fibrillation. In these patients, normalisation of heart rate using any of the two methods (rate or rhythm control) improves systolic function, in case of tachycardia induced cardiomyopathy. However, in other clinical settings, treatment of tachycardia induced cardiomyopathy should aim at the termination of the responsible arrhythmia, which may require antiarrhythmic drug therapy, direct current (DC) cardioversion, or catheter ablation. For patients with supraventricular tachyarrhythmias, if control of the arrhythmia cannot be achieved by other means, atrioventricular junction conduction ablation combined with pacemaker implantation can be an option.  Drug treatment of heart failure (HF) is also provided, as needed, according to the general indications and guidelines (e.g. an ACE-inhibitor, beta blocker-also useful for the control of heart rate, loop diuretic, digoxin, aldosterone antagonist, may be needed as part of the HF treatment). 

Links and Bibliography
 A VIDEO : I highly recommend this video with clinical questions and most importantly echocardiographic images of various cardiomyopathies ( You Tube -Mayo Clinic -Dr  Steve R. Ommen)

Classification of the cardiomyopathies: a position statement from the european society of cardiology 

Maron BJ, Towbin JA, et al Contemporary Definitions and Classification of the Cardiomyopathies. Circulation. 2006;113:1807-1816 (AHA SCIENTIFIC STATEMENT)

Nishimura RA, Holmes DR. Hypertrophic obstructive cardiomyopathy. N Engl J Med. 2004;350:1320-1327.

Watkins H, Ashrafian H, Redwood C. Inherited cardiomyopathies. N Engl J Med 2011;

Marcus FI, McKenna WJ, Sherrill D, et al. Diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia: proposed modification of the task force criteria. Circulation. 2010;121:1533-1541

Kushwaha SS, Fallon JT, Fuster V. Restrictive cardiomyopathy. N Engl J Med. 1997;336:267-276.

Behere SP, Weindling SN. Inherited arrhythmias: The cardiac channelopathies.Annals of Pediatric Cardiology. 2015;8: 210-220. LINK

Hilfiker-Kleiner D, Haghikia A, et al . Peripartum cardiomyopathy: current management and future perspectives. European Heart Journal 2015, doi:10.1093/eurheartj/ehv009

Perez-Silva A, Merino JS, Tachycardia-induced cardiomyopathy E-Journal-of-Cardiology-Practice 2019 ;7