Cardiomyopathy is a disease of the heart muscle in which the myocardium becomes enlarged, thickened, or rigid, impairing the heart’s ability to pump blood effectively. Causes include genetic mutations, chronic high blood pressure, coronary disease, alcohol abuse, and nutritional deficiencies such as severe thiamine deficiency in beriberi or selenium deficiency in Keshan disease. Symptoms progress from breathlessness and fatigue to heart failure. Nutritional management supports treatment through sodium restriction, fluid balance, and correction of deficiencies, alongside medication and devices. Some forms are reversible when the cause, such as alcohol or a nutrient deficiency, is removed early.