Cardiomyopathy: Understanding Its Definition and Classification

Cardiomyopathy refers to a group of heart diseases primarily affecting the heart muscle, not caused by congenital malformations, systemic or pulmonary hypertension, valvular heart disease, or coronary artery disease. These conditions often lead to structural and functional abnormalities of the heart, with clinical manifestations including heart enlargement, arrhythmias, heart failure, and the potential for thromboembolic events.

Types of Cardiomyopathy

Cardiomyopathy can be broadly classified into two main categories: primary and secondary. Primary cardiomyopathy originates within the heart muscle itself and may be further divided into familial and non-familial types. Specific forms include endomyocardial fibrosis, fibroelastosis, peripartum cardiomyopathy, and Keshan disease, among others. These conditions may have genetic, environmental, or idiopathic causes.

Secondary Cardiomyopathy: Common Causes

Secondary cardiomyopathy develops as a result of external factors or underlying conditions that affect the heart muscle. This category encompasses a wide range of etiologies, including:

Infectious Causes

These forms arise from myocardial inflammation caused by various pathogens, such as viral, bacterial, or parasitic infections. Myocarditis can progress to chronic cardiomyopathy if left untreated or if the heart muscle sustains long-term damage.

Nutritional and Metabolic Disorders

Certain metabolic conditions can lead to heart muscle dysfunction. Examples include obesity-related cardiomyopathy, anemia-induced heart disease, diabetic cardiomyopathy, and uremic cardiomyopathy associated with chronic kidney disease.

Endocrine-Related Cardiomyopathy

Hormonal imbalances can significantly impact heart function. Conditions such as hyperthyroidism or hypothyroidism may lead to cardiac changes that resemble cardiomyopathy if not properly managed.

Connective Tissue Diseases

Autoimmune disorders like rheumatoid arthritis, systemic lupus erythematosus, and polyarteritis nodosa can cause myocardial damage due to chronic inflammation and immune-mediated injury to the heart tissue.

Neuromuscular Disorders

Genetic conditions such as hereditary ataxia and progressive muscular dystrophy can affect the heart muscle as part of a broader systemic disease process, leading to cardiomyopathy.

Toxic and Allergic Reactions

Exposure to certain drugs, heavy metals (like arsenic or mercury), carbon monoxide, alcohol, venom from snakes or scorpions, and even radiation therapy can cause direct damage to the myocardium, resulting in toxic cardiomyopathy.

Neoplastic and Hematologic Conditions

Disorders like polycythemia vera, multiple myeloma, and other blood-related cancers can infiltrate or impair the heart muscle, causing secondary cardiomyopathy due to direct cellular invasion or metabolic disruption.