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{{Cardiac amyloidosis}}
{{Cardiac amyloidosis}}
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==Overview==
==Overview==
'''Cardiac amyloidosis''' is a well-known condition, which has been reported with varying incidence rates. Myocardial involvement results in severe dysfunction and is the leading cause of death in patients with amyloidosis. Systemic amyloidosis of AL and TTR type is often associated with amyloid deposition in heart valves, in addition to blood vessels and myocardium <ref>Pomerance, A. The pathology of senile cardiac amyloidosis. J. Pathol. Bacteriol. 91, 357. 1966</ref> <ref>Buja, L. M., Khoi, N. B., and Roberts W. C. Clinically significant cardiac amyloidosis. Clinicopathologic findings in 15 patients. Am. J. Cardiol., 26, 394. 1970</ref> In this classical type of valvular amyloidosis are the deposits occur in previously unaltered valves.
Cardiac amyloidosis is a well-known progressive condition, which has been reported with varying [[incidence]] rates. It refers to [[extracellular]] deposition of [[light chain]]s of some [[serum]] [[Protein|proteins]], that assume a beta pleated structure. [[Myocardium|Myocardial]] involvement results in [[congestive heart failure]] and [[fatal]] [[arrhythmias]] and is the leading cause of [[death]] in [[Patient|patients]] with amyloidosis. Systemic amyloidosis of [[Primary amyloidosis|AL]] and TTR type is often associated with [[amyloid]] deposition in [[Heart valve|heart valves]], in addition to [[Blood vessel|blood vessels]] and [[myocardium]]. In this classical type of valvular amyloidosis, the deposits occur in previously unaltered [[Heart valve|valves]]. There is also another type of cardiac amyloidosis restricted entirely to the heart valves (surgically removed for chronic valvular disease) or only the [[Atrium (heart)|atria]] (also called isolated atrial amyloidosis). This condition is heavily under-diagnosed because the thickening of [[Ventricle|ventricles]] from [[extracellular]] deposition of [[amyloid]] material in the [[heart]] is mostly attributed to [[chronic hypertension]], which is also a feature of cardiac amyloidosis. Cardiac amyloidosis should be suspected in the following scenarios:


There is also another type of cardiac amyloidosis restricted entirely to the heart valves and can be found in valves, surgically removed for chronic valvular disease. The deposits are small and restricted to the areas of scarring and calcification.<ref>Goffin, Y. A. Microscopic amyloid deposits in the heart valves: a common local complication of chronic damage and scarring. J. Clin. Pathol., 33, 262. 1980</ref> The amyloid protein has not been identified but it has been demonstrated not to be AL or AA <ref>Goffin, Y. A., Murdoch, W., Cornwell, G. G. III, and Sorenson, G. D. Microdeposits of amyloid in sclerocalcific heart valves: a histochemical and immunoflourescence study. J. Clin. Pathol., 36, 1342. 1983</ref> <ref>Amyloid and amyloidosis. Gilles Grateau, Robert A. Kyle, Martha Skinner, 2005 ISBN 0-8493-3534-5</ref>
* [[Congestive heart failure]] and an increase in [[Left ventricle|left ventricular]] wall thickness (> 12 mm) in the absence of [[hypertension]] or other causes of increased [[Left ventricle|left ventricular]] mass
 
* [[Congestive heart failure]] and an increase in [[Left ventricle|left ventricular]] wall thickness (> 12 mm) in the absence of [[hypertension]] or other causes of increased [[Left ventricle|left ventricular]] mass in an African-American > 60 years old
 
*[[HFpEF|Congestive heart failure with preserved left ventricular ejection fraction fraction (HFPEF)]] in an individual > 60 years old
 
* [[Congestive heart failure]] in an individual (particularly an elderly male) with unexplained [[neuropathy]], bilateral [[carpal tunnel syndrome]] without risk factors, [[atrial fibrillation]]
 
*[[Medical sign|Signs]] or [[Symptom|symptoms]] in an individual with a [[family history]] of amyloidosis
 
* Individuals with hyperenhancement on [[Cardiac magnetic resonance|Cardiac Magnetic Resonance (CMR)]] or echogenicity on [[echocardiography]]
 
==Historical Perspective==
In 1639, Nicolaus Fontanus [[Autopsy|autopsied]] a young man who had [[ascites]], [[jaundice]], [[liver abscess]], and [[splenomegaly]] and his report has been the first description of amyloidosis. There is no significant data regarding the historical perspective of amyloidosis throughout the 18th century. Rudolph Virchow and Weber are the prominent figures with substantial work on amyloidosis during the 19th century. In 1922, Bennhold introduced [[Congo red|Congo Red staining]] of [[amyloid]] that remains the [[Gold standard (test)|gold standard]] for [[diagnosis]].
 
==Classification==
Cardiac amyloidosis can be [[Classification|classified]] based on the type of [[amyloid]] that infiltrates the [[heart]]. The types of [[amyloid]] that commonly deposit in the [[heart]] are immunoglobulin light chain (AL) and transthyretin (ATTR). These two types of [[amyloid]] can result in cardiac AL amyloidosis and cardiac transthyretin amyloidosis.
 
==Pathophysiology==
The characteristic feature of cardiac amyloidosis is abnormal deposition of abnormally folded [[light chain]]s of several [[serum]] [[Protein|proteins]], making them insoluble and leading to their accumulation in various [[Organ (anatomy)|organs]]. This abnormal folding of [[Protein|proteins]] is most commonly a result of [[genetic mutations]] or excessive formation. Involvement of [[cardiac muscle]] can lead to [[heart failure]], [[arrhythmia]]s, and advanced [[cardiac conduction disorder]]s.
 
==Causes==
The causes of cardiac amyloidosis vary based on the cause of the [[systemic]] [[amyloidosis]].
 
==Differentiating Cardiac Amyloidosis from other Diseases==
[[Cardiomyopathy]] with [[congestive heart failure]] is the most common presentation of cardiac amyloidosis. Other common causes of [[cardiomyopathy]] should be excluded, and cardiac amyloidosis should be considered in the absence of a history of myocaridal [[ischemia]], [[myocardial infarction]], or presence of [[coronary artery disease]] risk factors. Cardiac amyloidosis should be included in the differential diagnoses in patients with [[Congestive heart failure|unexplained congestive heart failure]] who have no history of [[valvular heart disease]], [[Hypertension|long-standing hypertension]], or myocardial [[ischemia]].
 
==Epidemiology and Demographics==
The [[incidence]] rate increased from 18 to 55 per 100,000 person-years from 2000 to 2012. The [[prevalence]] rate increased from 8 to 17 per 100 000 person-years from 2000 to 2012. Cardiac amyloidosis commonly presents in adults more than 40 years old. The [[incidence]] and [[prevalence]] of cardiac amyloidosis have increased among blacks from 2000 to 2012. Over the years, both [[incidence]] and [[prevalence]] of cardiac amyloidosis have increased among men.
 
==Risk Factors==
The most common [[risk factor]] for the development of cardiac amyloidosis is the presence of an underlying [[plasma cell dyscrasia]].
 
==Screening==
There is insufficient evidence to recommend routine [[Screening (medicine)|screening]] for cardiac amyloidosis.
 
==Natural History, Complications, and Prognosis==
The presence or absence of cardiac involvement with amyloid is the most important prognostic factor. Untreated cardiac amyloidosis is associated with a very poor prognosis and a high mortality rate. The most common cardiac complications include [[heart failure]], [[sudden cardiac death]] due to [[electromechanical dissociation]] and [[pericardial effusion]].
 
==Diagnosis==
===Diagnostic Study of Choice===
A cardiac [[biopsy]] that reveals [[amyloid]], confirms the [[diagnosis]]. [[Biopsy]] of other [[tissues]] may also confirm the [[diagnosis]] of a systemic involvement. Amyloidosis is frequently confirmed by [[biopsy]] of [[Abdomen|abdominal]] [[fat]], [[rectal]] [[submucosa]], [[kidney]], or [[bone marrow]].
 
===History and Symptoms===
Amyloidosis is a multi-system disease involving many organs simultaneously. Approximately 50% of patients with cardiac amyloidosis present with [[right heart failure]] symptoms. The most common symptoms observed in patients with cardiac amyloidosis include [[fatigue]], [[weight loss]], and [[Purpura|periorbital purpura]].
 
===Physical Examination===
Cardiac amyloidosis is difficult to [[Diagnosis|diagnose]]. More than 50% of the [[Patient|patients]] with cardiac amyloidosis present with [[Medical sign|signs]] and [[Symptom|symptoms]] suggestive of [[right heart failure]]. Common [[physical exam]] findings include elevated [[jugular venous pressure]], [[third heart sound]] and [[pedal edema]].
 
===Laboratory Findings===
There is no single specific [[diagnostic test]] that can be used to diagnose amyloidosis and the [[diagnosis]] is based upon the totality of the data. Hence, awareness of the [[disease]] is necessary to identify [[Patient|patients]] with amyloidosis.
 
===Electrocardiogram===
The combination of low voltage electrocardiographic pattern and increased thickness of the left ventricular posterior wall and interventricular septum on echocardiogram is highly specific for cardiac amyloidosis. Conduction and rhythm disturbances are common in cardiac amyloidosis, however direct infiltration of the specialized conduction tissue of the heart by the amyloid does not account for the majority of these disturbances.
 
===Imaging===
====Cardiac MRI====
[[Amyloidosis]] is an infiltrative disease resulting in deposition of [[amyloid]] in the extracellular spaces of the tissues. Amyloid infiltration of the heart leads to expansion of these extracellular spaces resulting in retainment of [[gadolinium]] dye during cardiac magnetic resonance imaging. This retainment of gadolinium leads to signal enhancement in the late washout phase during delayed enhanced cardiac imaging.
 
====Echocardiography====
[[Transthoracic echocardiography]] is most commonly used in the initial evaluation of cardiac amyloidosis. The most common echocardiographic finding is thickening of the [[left ventricle]].  Echocardiographic findings strongly correlate with the degree of cardiac dysfunction and disease progression with mildly or moderately increased wall thickness in the early asymptomatic phase and severe thickening and [[hypokinesia]] of the left ventricular posterior wall and [[interventricular septum]] in clinically apparent [[cardiac dysfunction]].  Echocardiographic findings have both diagnostic and prognostic importance.
 
====Other Imaging Findings====
Nuclear cardiac scans like [[MUGA scan|MUGA]] and radionuclide ventriculography (RNV) are not used routinely early in the diagnosis of cardiac amyloidosis. However, when performed, these scans show increased uptake of technetium by the myocardium correlating well with the degree of involvement.
 
===Cardiac Biopsy===
A cardiac [[biopsy]] that reveals [[amyloid]] confirms the diagnosis. Biopsy of other tissues may also confirm the diagnosis. Amyloidosis is frequently confirmed by biopsy of abdominal [[fat]], rectal submucosa, [[kidney]], or [[bone marrow]].
 
==Treatment==
===Medical Therapy===
Major cardiac manifestations of systemic amyloidosis include [[heart failure]] and fatal [[arrhythmias]]. Therefore treatment of cardiac amyloidosis includes treatment of heart failure and arrhythmias and treatment of the underlying disease. Treatment of heart failure associated with cardiac amyloidosis differs from therapy usually attempted in patients with systolic or [[diastolic dysfunction]].
 
===Surgery===
When heart function is very poor, a heart transplant may be considered for some patients, but not those with AL type amyloidosis since their disease compromises many organs. In one type of secondary amyloidosis, [[liver]] transplantation is also required.
 
===Future or Investigational Therapies===
New therapies targeting the serum amyloid protein (SAP), which is an excellent immunogen and a universal component of all amyloid deposits, using monoclonal antibodies are currently being investigated.


==References==
==References==
{{reflist|2}}
{{reflist|2}}
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Latest revision as of 19:36, 19 November 2019

Cardiac amyloidosis Microchapters

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Overview

Historical Perspective

Classification

Pathophysiology

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Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Diagnostic Study of Choice

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aarti Narayan, M.B.B.S [2]; Raviteja Guddeti, M.B.B.S. [3]

Overview

Cardiac amyloidosis is a well-known progressive condition, which has been reported with varying incidence rates. It refers to extracellular deposition of light chains of some serum proteins, that assume a beta pleated structure. Myocardial involvement results in congestive heart failure and fatal arrhythmias and is the leading cause of death in patients with amyloidosis. Systemic amyloidosis of AL and TTR type is often associated with amyloid deposition in heart valves, in addition to blood vessels and myocardium. In this classical type of valvular amyloidosis, the deposits occur in previously unaltered valves. There is also another type of cardiac amyloidosis restricted entirely to the heart valves (surgically removed for chronic valvular disease) or only the atria (also called isolated atrial amyloidosis). This condition is heavily under-diagnosed because the thickening of ventricles from extracellular deposition of amyloid material in the heart is mostly attributed to chronic hypertension, which is also a feature of cardiac amyloidosis. Cardiac amyloidosis should be suspected in the following scenarios:

Historical Perspective

In 1639, Nicolaus Fontanus autopsied a young man who had ascites, jaundice, liver abscess, and splenomegaly and his report has been the first description of amyloidosis. There is no significant data regarding the historical perspective of amyloidosis throughout the 18th century. Rudolph Virchow and Weber are the prominent figures with substantial work on amyloidosis during the 19th century. In 1922, Bennhold introduced Congo Red staining of amyloid that remains the gold standard for diagnosis.

Classification

Cardiac amyloidosis can be classified based on the type of amyloid that infiltrates the heart. The types of amyloid that commonly deposit in the heart are immunoglobulin light chain (AL) and transthyretin (ATTR). These two types of amyloid can result in cardiac AL amyloidosis and cardiac transthyretin amyloidosis.

Pathophysiology

The characteristic feature of cardiac amyloidosis is abnormal deposition of abnormally folded light chains of several serum proteins, making them insoluble and leading to their accumulation in various organs. This abnormal folding of proteins is most commonly a result of genetic mutations or excessive formation. Involvement of cardiac muscle can lead to heart failure, arrhythmias, and advanced cardiac conduction disorders.

Causes

The causes of cardiac amyloidosis vary based on the cause of the systemic amyloidosis.

Differentiating Cardiac Amyloidosis from other Diseases

Cardiomyopathy with congestive heart failure is the most common presentation of cardiac amyloidosis. Other common causes of cardiomyopathy should be excluded, and cardiac amyloidosis should be considered in the absence of a history of myocaridal ischemia, myocardial infarction, or presence of coronary artery disease risk factors. Cardiac amyloidosis should be included in the differential diagnoses in patients with unexplained congestive heart failure who have no history of valvular heart disease, long-standing hypertension, or myocardial ischemia.

Epidemiology and Demographics

The incidence rate increased from 18 to 55 per 100,000 person-years from 2000 to 2012. The prevalence rate increased from 8 to 17 per 100 000 person-years from 2000 to 2012. Cardiac amyloidosis commonly presents in adults more than 40 years old. The incidence and prevalence of cardiac amyloidosis have increased among blacks from 2000 to 2012. Over the years, both incidence and prevalence of cardiac amyloidosis have increased among men.

Risk Factors

The most common risk factor for the development of cardiac amyloidosis is the presence of an underlying plasma cell dyscrasia.

Screening

There is insufficient evidence to recommend routine screening for cardiac amyloidosis.

Natural History, Complications, and Prognosis

The presence or absence of cardiac involvement with amyloid is the most important prognostic factor. Untreated cardiac amyloidosis is associated with a very poor prognosis and a high mortality rate. The most common cardiac complications include heart failure, sudden cardiac death due to electromechanical dissociation and pericardial effusion.

Diagnosis

Diagnostic Study of Choice

A cardiac biopsy that reveals amyloid, confirms the diagnosis. Biopsy of other tissues may also confirm the diagnosis of a systemic involvement. Amyloidosis is frequently confirmed by biopsy of abdominal fat, rectal submucosa, kidney, or bone marrow.

History and Symptoms

Amyloidosis is a multi-system disease involving many organs simultaneously. Approximately 50% of patients with cardiac amyloidosis present with right heart failure symptoms. The most common symptoms observed in patients with cardiac amyloidosis include fatigue, weight loss, and periorbital purpura.

Physical Examination

Cardiac amyloidosis is difficult to diagnose. More than 50% of the patients with cardiac amyloidosis present with signs and symptoms suggestive of right heart failure. Common physical exam findings include elevated jugular venous pressure, third heart sound and pedal edema.

Laboratory Findings

There is no single specific diagnostic test that can be used to diagnose amyloidosis and the diagnosis is based upon the totality of the data. Hence, awareness of the disease is necessary to identify patients with amyloidosis.

Electrocardiogram

The combination of low voltage electrocardiographic pattern and increased thickness of the left ventricular posterior wall and interventricular septum on echocardiogram is highly specific for cardiac amyloidosis. Conduction and rhythm disturbances are common in cardiac amyloidosis, however direct infiltration of the specialized conduction tissue of the heart by the amyloid does not account for the majority of these disturbances.

Imaging

Cardiac MRI

Amyloidosis is an infiltrative disease resulting in deposition of amyloid in the extracellular spaces of the tissues. Amyloid infiltration of the heart leads to expansion of these extracellular spaces resulting in retainment of gadolinium dye during cardiac magnetic resonance imaging. This retainment of gadolinium leads to signal enhancement in the late washout phase during delayed enhanced cardiac imaging.

Echocardiography

Transthoracic echocardiography is most commonly used in the initial evaluation of cardiac amyloidosis. The most common echocardiographic finding is thickening of the left ventricle. Echocardiographic findings strongly correlate with the degree of cardiac dysfunction and disease progression with mildly or moderately increased wall thickness in the early asymptomatic phase and severe thickening and hypokinesia of the left ventricular posterior wall and interventricular septum in clinically apparent cardiac dysfunction. Echocardiographic findings have both diagnostic and prognostic importance.

Other Imaging Findings

Nuclear cardiac scans like MUGA and radionuclide ventriculography (RNV) are not used routinely early in the diagnosis of cardiac amyloidosis. However, when performed, these scans show increased uptake of technetium by the myocardium correlating well with the degree of involvement.

Cardiac Biopsy

A cardiac biopsy that reveals amyloid confirms the diagnosis. Biopsy of other tissues may also confirm the diagnosis. Amyloidosis is frequently confirmed by biopsy of abdominal fat, rectal submucosa, kidney, or bone marrow.

Treatment

Medical Therapy

Major cardiac manifestations of systemic amyloidosis include heart failure and fatal arrhythmias. Therefore treatment of cardiac amyloidosis includes treatment of heart failure and arrhythmias and treatment of the underlying disease. Treatment of heart failure associated with cardiac amyloidosis differs from therapy usually attempted in patients with systolic or diastolic dysfunction.

Surgery

When heart function is very poor, a heart transplant may be considered for some patients, but not those with AL type amyloidosis since their disease compromises many organs. In one type of secondary amyloidosis, liver transplantation is also required.

Future or Investigational Therapies

New therapies targeting the serum amyloid protein (SAP), which is an excellent immunogen and a universal component of all amyloid deposits, using monoclonal antibodies are currently being investigated.

References


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