Cardiomyopathy

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Edzel Lorraine Co, DMD, MD[2] Muhammad Saad, M.B.B.S.[3]

Cardiomyopathy refers to diseases that involve the heart muscle and leads to its abnormal function and/or structure, in the absence of coronary artery disease, hypertension, valvular disease or congenital heart disease that would explain the myocardium dysfunction.

Cardiomyopathies can generally be categorized into two groups (based on World Health Organization guidelines): extrinsic cardiomyopathies and intrinsic cardiomyopathies ^[1]. Cardiomyopathy can also be classified from a clinical standpoint, as to whether it is restrictive, dilated, or hypertrophic.

There is a very wide range of factors that can cause cardiomyopathy, ranging from infectious causes, toxins, genetic causes and other disease processes.

Some of the risk factors for developing cardiomyopathy include: a family history of cardiomyopathy, heart failure or sudden death, a history of other diseases that may lead to cardiomyopathy, obesity, alcoholism, and long standing high blood pressure. Certain diseases such as hemochromatosis, amyloidosis, and sarcoidosis also increase the risk of developing cardiomyopathy.

Cardiomyopathy will continue to progressively worsen, unless intervened on. Complications and sequelae of cardiomyopathy include heart failure, arrythmia, thromboembolic disease, and sudden cardiac death.

Patients may be asymptomatic in early stages of disease. When symptoms occur, they include: shortness of breath, edema of the lower extremities, fatigue, loss of consciousness, and palpitations due to arrythmias.

A thorough physical examination can help in diagnosing cardiomyopathy. Particular attention should be given to the cardiac exam, the lung exam, the extremities for edema, and in assessing for other signs of heart failure such as jugular venous distension.

A chest x ray also shows fluid build-up, or a pleural effusion in the lungs, which can be a sign of the complication of heart failure.

Treatment is phenotype-directed and includes guideline-directed medical therapy (GDMT) for heart failure syndromes and targeted therapy for specific cardiomyopathies such as hypertrophic cardiomyopathy (HCM). In HCM, management includes symptom-directed pharmacotherapy (beta-blocker or nondihydropyridine calcium-channel blocker, with disopyramide or a cardiac myosin inhibitor in selected adults with obstructive physiology), risk-based use of ICDs, and septal reduction therapy at experienced centers when symptoms persist despite medical therapy.^{[2] [3]}For cardiomyopathy with HFrEF, foundational GDMT consists of an ARNI/ACE inhibitor/ARB, evidence-based beta-blocker, mineralocorticoid receptor antagonist, and SGLT2 inhibitor, with additional therapies and device-based treatment individualized by EF, QRS, symptoms, and comorbidities.^[3] Goals include symptom relief, prevention of sudden cardiac death (when relevant, e.g., HCM), and modification of heart-failure trajectory; patients with advanced heart failure despite GDMT should be referred to an advanced HF team for consideration of transplant and/or durable mechanical circulatory support.^[4] In HCM with atrial fibrillation, oral anticoagulation is recommended irrespective of CHA₂DS₂-VASc, and rhythm and/or rate control should be individualized.^[2]

Procedural and surgical options are phenotype-specific and should be performed at experienced centers when indicated.^[2] For symptomatic obstructive HCM refractory to medical therapy, septal reduction therapy includes surgical septal myectomy or (in selected patients) alcohol septal ablation. Advanced heart failure may require durable mechanical circulatory support and/or heart transplantation after evaluation by an advanced HF team.^[2][4]

Primary prevention focuses on ‘at risk’ (Stage A) and ‘pre-HF’ (Stage B) management: control hypertension, diabetes, obesity, and other cardiovascular risk factors; avoid cardiotoxins (including excess alcohol and illicit drugs); and treat structural heart disease early to prevent progression to symptomatic HF.^[4][5]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Lina Ya’qoub,MD, Edzel Lorraine Co, DMD, MD[2]

In 1980, the World Health Organization (WHO) defined cardiomyopathies as “heart muscle diseases of unknown cause” to distinguish cardiomyopathy from cardiac dysfunction due to known cardiovascular causes such as hypertension, ischemic heart disease, or valvular disease. In clinical practice, however, the term “cardiomyopathy” had also been applied to diseases of known cardiovascular cause, including ischemic cardiomyopathy and hypertensive cardiomyopathy. As a result, the 1995 WHO/International Society and Federation of Cardiology (ISFC) Task Force on the Definition and Classification of the Cardiomyopathies expanded the classification to include all diseases affecting heart muscle and to take into consideration etiology as well as the dominant pathophysiology. In the 1995 classification, the cardiomyopathies were defined as “diseases of the myocardium associated with cardiac dysfunction.”

• In 1980, the World Health Organization (WHO) defined cardiomyopathies as “heart muscle diseases of unknown cause” to distinguish cardiomyopathy from cardiac dysfunction due to known cardiovascular causes such as hypertension, ischemic heart disease, or valvular disease.
• In clinical practice, however, the term “cardiomyopathy” had also been applied to diseases of known cardiovascular cause, including ischemic cardiomyopathy and hypertensive cardiomyopathy.
• As a result, the 1995 WHO/International Society and Federation of Cardiology (ISFC) Task Force on the Definition and Classification of the Cardiomyopathies expanded the classification to include all diseases affecting heart muscle and to take into consideration etiology as well as the dominant pathophysiology.
• In the 1995 WHO classification, the cardiomyopathies were defined as “diseases of the myocardium associated with cardiac dysfunction.”

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References:

1-Report of the WHO/ISFC task force on the definition and classification of cardiomyopathies. Br Heart J 1980; 44:672.

2- Richardson P, McKenna W, Bristow M, et al. Report of the 1995 World Health Organization/International Society and Federation of Cardiology Task Force on the Definition and Classification of cardiomyopathies. Circulation 1996; 93:841.

3- Maron BJ, Towbin JA, Thiene G, et al. Contemporary definitions and classification of the cardiomyopathies: an American Heart Association Scientific Statement from the Council on Clinical Cardiology, Heart Failure and Transplantation Committee; Quality of Care and Outcomes Research and Functional Genomics and Translational Biology Interdisciplinary Working Groups; and Council on Epidemiology and Prevention. Circulation 2006; 113:1807.

4- Elliott P, Andersson B, Arbustini E, et al. Classification of the cardiomyopathies: a position statement from the European Society Of Cardiology Working Group on Myocardial and Pericardial Diseases. Eur Heart J 2008; 29:270.

5- WRITING COMMITTEE MEMBERS, Yancy CW, Jessup M, et al. 2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines. Circulation 2013; 128:e240.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Lina Ya’qoub,MD; Edzel Lorraine Co, DMD, MD[2]

Incidence and prevalence differ based on cause. The incidence of DCM has been estimated to be 5-8 cases per 100,000 population, with a prevalence of 36 per 100,000. This could be explained by the incomplete disease expression, which goes unrecognized. The prevalence of HCM in the absence of aortic valve disease or systemic hypertension is at least 200 per 100,000 of the adult population. RCM is much less common than either DCM or HCM in the developed world, but is a frequent cause of death in the tropical countries, primarily because of the high incidence of endomyocardial fibrosis in those regions.

Incidence and prevalence differ based on cause.^[1]

• The incidence of DCM has been estimated to be 5-8 cases per 100,000 population, with a prevalence of 36 per 100,000. This could be explained by the incomplete disease expression, which goes unrecognized.^[2]
• The prevalence of HCM in the absence of aortic valve disease or systemic hypertension is at least 200 per 100,000 of the adult population.^[3]
• RCM is much less common than either DCM or HCM in the developed world, but is a frequent cause of death in the tropical countries, primarily because of the high incidence of endomyocardial fibrosis in those regions.^[4]
• African–American individuals are approximately three times more prone to development of dilated cardiomyopathy.
• Hypertrophic cardiomyopathy has a prevalence of 400-800 per 100,0000 in adults. This prevalence seems to be similar in all races, but the disease age is mainly considered to be in adolescence and you adults.^[4]
• Dilated cardiomyopathy has an approximate incidence of 4.58 per 100,000 in children less than 1 year old. The incidence decrease when the child ages and is 0.34 per 100,000 between 1 to 18 years old. ^[4]

• The incidence of dilated cardiomyopathy was estimated to be 400-800 cases per 100,000 individuals worldwide.^[5]

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Edzel Lorraine Co, DMD, MD[2]

Some of the risk factors for developing cardiomyopathy include; a family history of cardiomyopathy, heart failure, or sudden death, a history of other diseases that may lead to cardiomyopathy, obesity, alcoholism, and long standing high blood pressure. Certain diseases such as hemachromotosis, amyloidosis, and sarcoidosis also increase the risk of developing cardiomyopathy.

Certain diseases, conditions, or factors can raise the risk for cardiomyopathy. Major risk factors include:^[1][2]

• A family history of cardiomyopathy, heart failure, or sudden cardiac arrest (SCA)
• A disease or condition that can lead to cardiomyopathy, such as coronary heart disease, heart attack, or a viral infection that inflames the heart muscle
• Diabetes or other metabolic diseases, or severe obesity
• Diseases that can damage the heart, such as hemochromatosis, sarcoidosis, or amyloidosis
• Long-term alcoholism
• Long-term high blood pressure

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Lina Ya’qoub, MD; Edzel Lorraine Co, DMD, MD[2]

Cardiomyopathy will continue to progressively worsen, unless intervened on. As the function of the heart deteriorates, symptoms of heart failure become apparent. On the other hand, defects in ion channels and hypertrophic cardiomyopathy can present with fatal arrhythmias and sudden cardiac death without the preceding symptoms of heart failure. In general, complications and sequelae of cardiomyopathy include heart failure, arrythmia, thromboembolic disease, and sudden cardiac death. Prognosis of patients depends on the etiology of the cardiomyopathy and the initiation of management, whether medical, surgical or device therapy. Patients with cardiomyopathy are usually treated with medical treatment similar to heart failure patients, although some patients do not respond well to medications and continue to have worsening heart function, which may require heart transplant eventually. Those patients at high risk for fatal arrhythmias and sudden cardiac death should receive device therapy with implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy (CRT).

• The symptoms of cardiolyopathy usually develop secondary to a predisposing factor and an underlying cause and start with symptoms such as fatigue, fever, and shortness of breath.
• Cardiomyopathy will continue to progressively worsen, unless intervened on.^[1][2]

Cardiomyopathy gets worse unless treated. The most likely complications are:^[3]

• Heart failure
• Arrythmia
• Thromboembolic disease
• Sudden cardiac death

Prognosis of patients depends on the etiology of the cardiomyopathy and the initiation of management, whether medical, surgical or device therapy:

• Patients with cardiomyopathy are usually treated with medical treatment similar to heart failure patients, although some patients do not respond well to medications and continue to have worsening heart function, which may require heart transplant eventually.
• Those patients at high risk for fatal arrhythmias and sudden cardiac death should receive device therapy with implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy (CRT).^[1][2][3]

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