Journal of Cardiology and Heart Failure

INTRODUCTION

Cardiomyopathy describes a condition which affects the muscle of the heart which affects the heart's ability to effectively pump blood to the body. This also encompasses a range of disorders with varying causes and outcomes which result in mechanical and electrical dysfunction of the myocardium. This condition can be primary (genetic or idiopathic) and secondary (causing infection to systemic diseases or exposure to toxins). This condition affects the heart's ability to pump effectively and result in numerous premature deaths, especially in young adults and athletes. In addition, it is also a major risk for heart failure and sudden death.

Classification of Cardiomyopathy

According to the American Heart Association and The World Health Organization, cardiomyopathy can be classified into multiple categories by their morphologies and four categories by their pathophysiologies:

• Dilated Cardiomyopathy (DCM): This condition shows dilation and impaired contraction of either the left ventricle and/or both ventricles. This form of the disease is the most common and is often associated with genetic mutations, viral illnesses, and toxic exposures.
• Hypertrophic Cardiomyopathy (HCM): This condition is characterized by primary and secondary causes described as the abnormal thickening of the ventricular walls, with a focus on the interventricular septum, and is often inherited in an autosomal dominant fashion.
• Restrictive Cardiomyopathy (RCM): This condition is described as having stiff ventricular walls which leading to having impaired filling during diastole while systolic function remains normal. This condition is associated with infiltrative diseases, for instance, fibrosis or amyloidosis.
• Arrhythmogenic Cardiomyopathy (ACM): This condition describes fibro-fatty replacement of the myocardium of the right or left ventricle which predisposes the patient to sudden cardiac death and arrhythmias.
• Takotsubo (Stress-Induced) Cardiomyopathy: This condition is often triggered by acute physical or emotional stress and is a transient condition that mimics a heart attack, however, it is not associated with any type of coronary obstruction.

Pathophysiology

Alterations of heart structure and function are the result of complex cellular and molecular mechanisms of cardiomyopathy. Dilated cardiomyopathy develops myocyte damage as well as cytoskeletal disruption which are responsible for the dilation and decrease of function of the ventricles. In hypertrophic cardiomyopathy, the mutations that happen in the sarcomeric proteins including the β-myosin heavy chain plus myosin-binding protein C are responsible for the irregular and excessive hypertrophy of the myocytes. Stiffening of the myocardium caused by fibrosis or amyloid deposit also leads to decreased diastolic filling and the condition is called restrictive cardiomyopathy. Arrhythmogenic cardiomyopathy is caused by mutations in the proteins that control cell adhesion to desmosomes (like desmoplakin and plakoglobin) leading to inflammation and fibrofatty replacement which are caused by detachment of the cells and the inflammation of the tissue. These changes on the molecular level cause changes to the heart muscle, cause faulty signaling via the heart and lead to heart failure that is progressive in nature.

Clinical Manifestations

The manifestation of cardiomyopathy will vary according to what type of myocardial dysfunction occurs and how severe it is. The most common include:

• Heart failure induced dyspnea on exertion and overall fatigue systems.
• Arrhythmia induced syncope and palpitations.
• Exercise associated chest pain and decreased tolerance to exertion.
• In severe cases congestive heart failure and its signs such as peripheral edema, ascites, and increased liver size.

Some of these cases are asymptomatic until cardiomyopathy is diagnosed. This emphasizes the need for early detection of cardiomyopathy.

Diagnostic Evaluation

Evaluating the patient’s medical history and performing physical exams that help decide the next steps is diagnostic cardiomyopathy. A few of these steps are:

• Echocardiography: Primary tool for assessing the chamber size, thickness of the wall, and function during contraction and relaxation of the heart.
• Cardiac MRI: Provides detailed structuring and tissue characterization, including fibrosis detection.
• Electrocardiography (ECG): Identifies electrical and rhythm abnormalities.
• Genetic Testing: Helps identify mutations in inherited cardiomyopathies, facilitating family screening.
• Endomyocardial Biopsy: This is occasionally performed to determine inflammatory or infiltrative causes.

Management and Treatment

The management of cardiomyopathy depends on the underlying type, cause, and severity:

• Pharmacological Therapy: Includes β-blockers, ACE inhibitors, ARBs, diuretics, and aldosterone antagonists to manage symptoms and prevent remodeling.
• Device Therapy: Implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy (CRT) are recommended in patients with reduced ejection fraction or life-threatening arrhythmias.
• Lifestyle Modification: Limiting alcohol intake, managing hypertension, and avoiding strenuous physical activity in hypertrophic cases.
• Advanced Therapies: Heart transplantation remains the ultimate treatment for end-stage heart failure due to irreversible cardiomyopathy.
• Genetic Counseling: Essential in inherited forms to assess familial risk and guide screening protocols.

Prognosis and Future Directions

The conditions known as cardiomyopathy are a diverse range of myocardial disorders, with varied underlying causes, clinical presentations, and outcomes. The knowledge and management of cardiomyopathy, as well as related conditions, have improved with the growth of molecular genetics, new imaging modalities, and more effective therapies. More studies are needed to develop effective treatments that remain the focus, improving the prognosis, survival, and quality of life of those that suffer with cardiomyopathy.

CONCLUSION

The conditions known as cardiomyopathy are a diverse range of myocardial disorders, with varied underlying causes, clinical presentations, and outcomes. The knowledge and management of cardiomyopathy, as well as related conditions, have improved with the growth of molecular genetics, new imaging modalities, and more effective therapies. More studies are needed to develop effective treatments that remain the focus, improving the prognosis, survival, and quality of life of those that suffer with cardiomyopathy.