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Dilated Cardiomyopathy

Updated : May 17, 2024





Background

Dilated cardiomyopathy affects the heart muscle, specifically the myocardium. In this condition, the heart becomes dilated and weakened, leading to a decrease in its ability to pump blood effectively. As a result, the ventricles may not be able to pump blood efficiently, and the heart’s ability to supply the body with oxygen and nutrients is compromised. Dilated cardiomyopathy is characterized by systolic dysfunction, where patients may or may not exhibit overt symptoms of heart failure. This condition is broadly classified into primary and secondary, with primary DCM considered idiopathic and diagnosed only after excluding secondary causes.

Typically progressive, DCM often culminates in heart failure and has a grim prognosis without transplantation. With diverse etiologies, all impacting ventricular function to varying extents, most DCM patients manifest symptoms, though a minority may remain asymptomatic due to compensatory mechanisms. The ongoing ventricular enlargement contributes to a gradual decline in function, subsequently leading to conduction system abnormalities, ventricular arrhythmias, thromboembolism, and eventual heart failure. Early identification and intervention play a pivotal role in prognosis improvement.

It is essential to recognize that prompt identification and treatment of individuals with DCM can significantly impact outcomes. The disease progression, marked by ventricular enlargement and functional decline, underscores the importance of early intervention to mitigate complications such as arrhythmias and heart failure. Without transplantation, DCM’s prognosis is notably challenging, emphasizing the critical role of timely medical attention and therapeutic strategies in enhancing survival rates.

Epidemiology

Dilated cardiomyopathy is relatively common, contributing significantly to worldwide heart failure cases. It can affect individuals of all ages, but it is often diagnosed in adults. Some studies may have a slight male predominance, suggesting that men are more frequently affected than women. Environmental factors, lifestyle, and genetic predispositions may contribute to these variations.

It is associated with certain conditions, such as viral infections, inflammatory diseases, and metabolic disorders. Conditions like hypertension and diabetes may also contribute to the development or exacerbation of dilated cardiomyopathy. The condition can lead to heart failure, arrhythmias, and other complications, impacting morbidity and mortality.

Anatomy

Pathophysiology

Numerous instances of dilated cardiomyopathy stem from an idiopathic origin, though it can also result from diverse myocardial insults. Ventricular enlargement may arise due to left ventricular failure or as a part of a primary cardiomyopathic process involving both systolic and diastolic dysfunction. The decline in systolic function is attributed to myocardial remodeling, causing an increase in both end-systolic and end-diastolic volumes.

The ongoing dilation of the ventricles induces significant tricuspid and mitral valve insufficiency, contributing to a further reduction in ejection fraction and an elevation in ventricular wall stress and end-systolic volumes. Initial compensatory mechanisms involve heightened heart rate and peripheral vascular system tone. However, these compensatory responses lead to geometric remodeling of the ventricles, ultimately exacerbating myocardial injury.

Concurrently, there is neurohumoral activation of the renin-angiotensin-aldosterone system, accompanied by elevated circulating levels of catecholamines. Additionally, there is an increase in levels of natriuretic peptides. Over time, these compensatory mechanisms become overwhelmed, culminating in heart failure.

Etiology

Genetic Mutations: DCM can be inherited, and specific genetic mutations are associated with an increased risk. Mutations in genes that encode proteins involved in myocardial structure and function can lead to familial DCM.

Environmental and Lifestyle Factors: Tobacco smoke contains harmful chemicals that can damage the heart muscle. Excess body weight can strain the heart and contribute to the development of cardiomyopathy.

Acquired or Secondary Factors:

  • Nutritional Deficiencies: Inadequate nutrition, particularly deficiencies in essential vitamins and minerals, can contribute to the development of DCM.
  • Metabolic Disorders: Conditions like diabetes and thyroid disorders can impact the heart and contribute to DCM.
  • Toxic Substances: Exposure to certain toxins, such as alcohol, cocaine, certain drugs, and heavy metals, can cause myocardial damage and contribute to DCM.

Genetics

Prognostic Factors

The overall prognosis for individuals diagnosed with dilated cardiomyopathy is uncertain. Most patients ultimately develop chronic heart failure, leading to considerations for advanced interventions like heart transplantation or assisted devices, which introduce additional morbidity.

The progression towards heart failure is contingent on factors such as the ejection fraction and the underlying cause of the disease. Alarmingly, nearly half of patients do not survive beyond a span of 5 years.

Clinical History

DCM can have a gradual onset, with symptoms developing over time, or it may manifest suddenly, especially in cases related to acute myocarditis. In some instances, DCM is asymptomatic initially, making early detection challenging. The duration of DCM varies among individuals. Some may experience a rapid progression, while others may have a more indolent course.

Dyspnea, particularly on exertion, may be an early symptom, progressing to difficulty breathing at rest as the disease advances. Palpitations or an irregular heartbeat may be indicative of arrhythmias associated with DCM. Syncope or near-syncope episodes may result from impaired cardiac function and reduced blood flow.

Chest pain may occur due to reduced blood flow or associated conditions. Fluid retention, leading to edema, is commonly observed in the legs and abdomen. Chronic disease often leads to prolonged management, focusing on symptom control and addressing the underlying causes.

Physical Examination

Classic symptoms of dilated cardiomyopathy encompass paroxysmal nocturnal dyspnea, leg swelling, orthopnea, and shortness of breath. Nonspecific manifestations, including malaise, fatigue, and weakness, can also be observed. In more complicated cases, complications such as thromboembolism, arrhythmias, conduction disturbances, or sudden cardiac death may manifest. Physical examination findings lack specificity for distinguishing from other causes of cardiomyopathy and are consistent with typical congestive heart failure indicators.

These include crackles in lung fields, peripheral edema, elevated jugular venous pressures, and an S3 gallop. Classically, the point of maximum impulse is displaced laterally. Murmurs indicative of mitral or tricuspid regurgitation may occur due to ventricular enlargement and annular dilation. Neck examination may reveal jugular venous distension, large V-waves, A-waves, and positive hepatojugular reflux.

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

Acute Pericarditis

Cardiac Tamponade

Hypertrophic Cardiomyopathy

Restrictive Cardiomyopathy

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

The treatment paradigm for dilated cardiomyopathy (DCM) typically involves a multifaceted approach aimed at managing symptoms, improving cardiac function, and preventing complications. Patients may be prescribed medications such as ACE inhibitors, beta-blockers, and diuretics to alleviate symptoms and reduce the strain on the heart. In some cases, anticoagulants may be necessary to prevent blood clots.

Cardiac rehabilitation and lifestyle modifications, including a heart-healthy diet and exercise, are essential to promote cardiovascular health. Devices like implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy (CRT) devices may be implanted for more advanced cases.

In severe cases, heart transplantation or ventricular assist devices (VADs) may be considered. Regular monitoring and close collaboration with healthcare providers are crucial to tailor the treatment to each patient’s unique needs and optimize their quality of life while managing DCM effectively.

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

Patients experiencing disease unresponsive to maximal medical therapy should be evaluated for cardiac transplantation or the placement of a left ventricular assist device (LVAD). LVADs can serve as a bridge to transplantation or a destination therapy for those ineligible.

For the primary prevention of sudden cardiac death and cardiac resynchronization therapy, implanted cardioverter-defibrillators are considered and endorsed by heart failure guidelines.

While heart transplant remains a viable option, the scarcity of donors poses a significant obstacle. Indications for heart transplant include refractory cardiogenic shock, reliance on high levels of inotropes, ventricular arrhythmias, and dependence on an intra-aortic balloon pump or a ventricular assist device.

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

Administration of a pharmaceutical agent

In acute exacerbation of congestive heart failure, intravenous loop diuretics are administered to address hypervolemia. For the management of chronic and stable heart failure, oral diuretics are often necessary to attain a euvolemic state. Angiotensin-converting enzyme inhibitors or angiotensin receptor blockers have demonstrated efficacy in treating heart failure with reduced ejection fraction and are recommended for individuals with dilated cardiomyopathy.

Aldosterone receptor blockade using medications like eplerenone, or spironolactone is also advised for patients in New York Heart Association heart failure classes II-IV with systolic dysfunction. Likewise, beta-blockers such as bisoprolol, carvedilol, or long-acting metoprolol are recommended for all patients with heart failure and reduced ejection fraction unless contraindications are present.

The combination of isosorbide dinitrate plus hydralazine has demonstrated increased survival rates, particularly in advanced cases of the disease. Anticoagulation therapy is warranted for patients with artificial heart valves, atrial fibrillation, or known mural thrombus. While oral anticoagulants can mitigate the risk of stroke, it is crucial to acknowledge the inherent risk of bleeding associated with their use. 

 

Medication

 

benziodarone 

Invivo studies suggests 100 mg daily



 
 

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References

Dilated Cardiomyopathy

Updated : May 17, 2024




Dilated cardiomyopathy affects the heart muscle, specifically the myocardium. In this condition, the heart becomes dilated and weakened, leading to a decrease in its ability to pump blood effectively. As a result, the ventricles may not be able to pump blood efficiently, and the heart’s ability to supply the body with oxygen and nutrients is compromised. Dilated cardiomyopathy is characterized by systolic dysfunction, where patients may or may not exhibit overt symptoms of heart failure. This condition is broadly classified into primary and secondary, with primary DCM considered idiopathic and diagnosed only after excluding secondary causes.

Typically progressive, DCM often culminates in heart failure and has a grim prognosis without transplantation. With diverse etiologies, all impacting ventricular function to varying extents, most DCM patients manifest symptoms, though a minority may remain asymptomatic due to compensatory mechanisms. The ongoing ventricular enlargement contributes to a gradual decline in function, subsequently leading to conduction system abnormalities, ventricular arrhythmias, thromboembolism, and eventual heart failure. Early identification and intervention play a pivotal role in prognosis improvement.

It is essential to recognize that prompt identification and treatment of individuals with DCM can significantly impact outcomes. The disease progression, marked by ventricular enlargement and functional decline, underscores the importance of early intervention to mitigate complications such as arrhythmias and heart failure. Without transplantation, DCM’s prognosis is notably challenging, emphasizing the critical role of timely medical attention and therapeutic strategies in enhancing survival rates.

Dilated cardiomyopathy is relatively common, contributing significantly to worldwide heart failure cases. It can affect individuals of all ages, but it is often diagnosed in adults. Some studies may have a slight male predominance, suggesting that men are more frequently affected than women. Environmental factors, lifestyle, and genetic predispositions may contribute to these variations.

It is associated with certain conditions, such as viral infections, inflammatory diseases, and metabolic disorders. Conditions like hypertension and diabetes may also contribute to the development or exacerbation of dilated cardiomyopathy. The condition can lead to heart failure, arrhythmias, and other complications, impacting morbidity and mortality.

Numerous instances of dilated cardiomyopathy stem from an idiopathic origin, though it can also result from diverse myocardial insults. Ventricular enlargement may arise due to left ventricular failure or as a part of a primary cardiomyopathic process involving both systolic and diastolic dysfunction. The decline in systolic function is attributed to myocardial remodeling, causing an increase in both end-systolic and end-diastolic volumes.

The ongoing dilation of the ventricles induces significant tricuspid and mitral valve insufficiency, contributing to a further reduction in ejection fraction and an elevation in ventricular wall stress and end-systolic volumes. Initial compensatory mechanisms involve heightened heart rate and peripheral vascular system tone. However, these compensatory responses lead to geometric remodeling of the ventricles, ultimately exacerbating myocardial injury.

Concurrently, there is neurohumoral activation of the renin-angiotensin-aldosterone system, accompanied by elevated circulating levels of catecholamines. Additionally, there is an increase in levels of natriuretic peptides. Over time, these compensatory mechanisms become overwhelmed, culminating in heart failure.

Genetic Mutations: DCM can be inherited, and specific genetic mutations are associated with an increased risk. Mutations in genes that encode proteins involved in myocardial structure and function can lead to familial DCM.

Environmental and Lifestyle Factors: Tobacco smoke contains harmful chemicals that can damage the heart muscle. Excess body weight can strain the heart and contribute to the development of cardiomyopathy.

Acquired or Secondary Factors:

  • Nutritional Deficiencies: Inadequate nutrition, particularly deficiencies in essential vitamins and minerals, can contribute to the development of DCM.
  • Metabolic Disorders: Conditions like diabetes and thyroid disorders can impact the heart and contribute to DCM.
  • Toxic Substances: Exposure to certain toxins, such as alcohol, cocaine, certain drugs, and heavy metals, can cause myocardial damage and contribute to DCM.

The overall prognosis for individuals diagnosed with dilated cardiomyopathy is uncertain. Most patients ultimately develop chronic heart failure, leading to considerations for advanced interventions like heart transplantation or assisted devices, which introduce additional morbidity.

The progression towards heart failure is contingent on factors such as the ejection fraction and the underlying cause of the disease. Alarmingly, nearly half of patients do not survive beyond a span of 5 years.

DCM can have a gradual onset, with symptoms developing over time, or it may manifest suddenly, especially in cases related to acute myocarditis. In some instances, DCM is asymptomatic initially, making early detection challenging. The duration of DCM varies among individuals. Some may experience a rapid progression, while others may have a more indolent course.

Dyspnea, particularly on exertion, may be an early symptom, progressing to difficulty breathing at rest as the disease advances. Palpitations or an irregular heartbeat may be indicative of arrhythmias associated with DCM. Syncope or near-syncope episodes may result from impaired cardiac function and reduced blood flow.

Chest pain may occur due to reduced blood flow or associated conditions. Fluid retention, leading to edema, is commonly observed in the legs and abdomen. Chronic disease often leads to prolonged management, focusing on symptom control and addressing the underlying causes.

Classic symptoms of dilated cardiomyopathy encompass paroxysmal nocturnal dyspnea, leg swelling, orthopnea, and shortness of breath. Nonspecific manifestations, including malaise, fatigue, and weakness, can also be observed. In more complicated cases, complications such as thromboembolism, arrhythmias, conduction disturbances, or sudden cardiac death may manifest. Physical examination findings lack specificity for distinguishing from other causes of cardiomyopathy and are consistent with typical congestive heart failure indicators.

These include crackles in lung fields, peripheral edema, elevated jugular venous pressures, and an S3 gallop. Classically, the point of maximum impulse is displaced laterally. Murmurs indicative of mitral or tricuspid regurgitation may occur due to ventricular enlargement and annular dilation. Neck examination may reveal jugular venous distension, large V-waves, A-waves, and positive hepatojugular reflux.

Acute Pericarditis

Cardiac Tamponade

Hypertrophic Cardiomyopathy

Restrictive Cardiomyopathy

The treatment paradigm for dilated cardiomyopathy (DCM) typically involves a multifaceted approach aimed at managing symptoms, improving cardiac function, and preventing complications. Patients may be prescribed medications such as ACE inhibitors, beta-blockers, and diuretics to alleviate symptoms and reduce the strain on the heart. In some cases, anticoagulants may be necessary to prevent blood clots.

Cardiac rehabilitation and lifestyle modifications, including a heart-healthy diet and exercise, are essential to promote cardiovascular health. Devices like implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy (CRT) devices may be implanted for more advanced cases.

In severe cases, heart transplantation or ventricular assist devices (VADs) may be considered. Regular monitoring and close collaboration with healthcare providers are crucial to tailor the treatment to each patient’s unique needs and optimize their quality of life while managing DCM effectively.

Patients experiencing disease unresponsive to maximal medical therapy should be evaluated for cardiac transplantation or the placement of a left ventricular assist device (LVAD). LVADs can serve as a bridge to transplantation or a destination therapy for those ineligible.

For the primary prevention of sudden cardiac death and cardiac resynchronization therapy, implanted cardioverter-defibrillators are considered and endorsed by heart failure guidelines.

While heart transplant remains a viable option, the scarcity of donors poses a significant obstacle. Indications for heart transplant include refractory cardiogenic shock, reliance on high levels of inotropes, ventricular arrhythmias, and dependence on an intra-aortic balloon pump or a ventricular assist device.

In acute exacerbation of congestive heart failure, intravenous loop diuretics are administered to address hypervolemia. For the management of chronic and stable heart failure, oral diuretics are often necessary to attain a euvolemic state. Angiotensin-converting enzyme inhibitors or angiotensin receptor blockers have demonstrated efficacy in treating heart failure with reduced ejection fraction and are recommended for individuals with dilated cardiomyopathy.

Aldosterone receptor blockade using medications like eplerenone, or spironolactone is also advised for patients in New York Heart Association heart failure classes II-IV with systolic dysfunction. Likewise, beta-blockers such as bisoprolol, carvedilol, or long-acting metoprolol are recommended for all patients with heart failure and reduced ejection fraction unless contraindications are present.

The combination of isosorbide dinitrate plus hydralazine has demonstrated increased survival rates, particularly in advanced cases of the disease. Anticoagulation therapy is warranted for patients with artificial heart valves, atrial fibrillation, or known mural thrombus. While oral anticoagulants can mitigate the risk of stroke, it is crucial to acknowledge the inherent risk of bleeding associated with their use. 

 

benziodarone 

Invivo studies suggests 100 mg daily