OVERVIEW
Cardiomyopathy (CMP) is disease affecting the heart muscles, making it harder for the heart muscle to pump blood and can lead to heart failure
Cardiomyopathy can also cause rhythm disturbances of the heart or arrhythmias
It can affect people of any age sex or ethnicity
CMP is one of the common indications for heart transplant
Recent major breakthrough in understanding of cardiomyopathies is employing gene testing that enables detection of the specific genetic mutations causing disease and carriers even before the person becomes symptomatic
Latest imaging techniques also better localization of the disease in the heart muscle and plan most optimal treatment possible. Also, new drugs are being developed to treat certain forms of CMP

TYPES OF CARDIOMYOPATHY
There are two broad types of cardiomyopathy

Primary cardiomyopathy – The patient does not have underlying heart cardiac conditions that can cause weakening of the heart muscle. Some of these cases are inherited and passed down from parents to offspring

Secondary cardiomyopathy – It is typically caused by pre-existing medical condition (such as congenital heart disease, coronary artery disease, hypertension, valvular heart disease or toxins/medications). Some of these conditions are treatable. The aim of treatment in persons with secondary cardiomyopathy is to identify and treat the underlying condition appropriately

Secondary cardiomyopathy can be further subdivided into
Ischemic cardiomyopathy (caused by coronary artery disease)
Non-ischemic cardiomyopathy – They are not associated with coronary artery disease but can be inherited in some cases. The four main types of secondary CMP include

Dilated CMP – Dilated cardiomyopathy (DCM) is commonest form of nonischemic cardiomyopathy. The heart’s main pumping chamber, the left ventricle becomes enlarged and dilated and unable to effectively pump blood due to weakening of the heart muscle

Hypertrophic CMP – Hypertrophic cardiomyopathy (HCM) involves thickening of the heart muscle, especially the ventricles, stiffness of ventricular muscle and mitral valve changes. Thickening of the heart muscle (myocardium) occurs most often in the septum, muscular wall that separates the right and left chambers of the heart. The thickened septum causes narrowing of the left ventricular cavity and reduces blood flow from the left ventricle to the aorta, referred to as “outflow tract obstruction.”

Restrictive CMP – It is the least common form of cardiomyopathy, in which the walls of the ventricles become extremely rigid and are unable to expand as the ventricles fill with blood.

Arrhythmogenic right ventricular dysplasia (ARVD) is a very rare form of cardiomyopathy but is the main reason of sudden death in young athletes. It is an inherited condition where right ventricular muscle is replaced by fat and scar tissue replace the muscle of the right ventricle leading to abnormal rhythms

CLINICAL FEATURES OF CMP
The various types of CMP may initially be asymptomatic but as the condition advances, symptoms may be evident including
• Shortness of breath (dyspnea) on exertion or even at rest
• Bloating of the abdomen due to fluid buildup
• Swelling of the legs, ankles and feet
• Cough while lying down
• Tiredness and fatigue
• Palpitation, rapid heartbeat, fluttering sensation in chest
• Chest discomfort, tightness or pain
• Fainting episodes, dizziness and lightheadedness

DIAGNOSIS OF CMP
If you consult a doctor with any of the above symptoms, he will take a detailed history including family history of similar symptoms, nature and duration of symptoms, potential trigger factors and conduct a thorough physical examination. If a diagnosis of cardiomyopathy is suspected, the following tests will be done to confirm or rule out the diagnosis

• Chest X-ray – Image of the heart that can demonstrated dilation of the left ventricle
• Echocardiogram – It is an ultrasound imaging of the heart and can show in real time any structural or functional abnormalities of the heart muscle, valves and any underlying condition that may be causing the symptoms
• Electrocardiogram (ECG) – Electrode patches are placed on the skin to evaluate electrical activity of the heart. It can detect arrhythmias, areas of ischemia and injury to heart that may be causing these symptoms
• Treadmill stress test – The patient is asked to walk on a treadmill while blood pressure, heart rhythm and breathing are monitored while you walk on a treadmill. This test may be done to check whether exercise triggers any abnormal rhythms
• Cardiac MRI – MRI produces high resolution images of the heart and can demonstrate evidence of underlying heart pathology, especially if echocardiogram is non-diagnostic
• Cardiac CT scan – The patient is made to lie on a table inside a circular machine. An x-ray tube within the machine rotates and captures images of the heart and other structures
• Cardiac catheterization. A thin tube (catheter) is inserted via the arm or thigh and maneuvered gradually through the blood vessels to the heart. Pressure within the heart chambers can be measured as well as narrowing of coronary arteries can be seen by injecting a contrast dye (angiogram). A sample of heart tissue (myocardial biopsy) can be obtained for histopathological examination
• Blood tests – Blood tests to evaluate thyroid, kidney and liver function, and estimation of serum iron levels
Another blood test measures B-type natriuretic peptide (BNP), a protein produced in the heart and becomes elevated in heart failure
• Genetic testing – Cardiomyopathy can be inherited. You may be referred for genetic screening as well as your first degree relatives including parents, children and siblings

TREATMENT OF CMP
The aim of treatment in persons with cardiomyopathy is to identify and treat the underlying condition appropriately and provide symptomatic relief

MEDICATION – Medications to improve heart’s pumping ability, lower blood pressure (antihypertensives), slow heart rate (eg beta blockers), improve blood flow (vasodilators), remove excess fluid from body (diuretics)and prevent clot formation (anti-platelets/anticoagulant) may be prescribed

SURGICALLY IMPLANTED DEVICES
Various devices can be implanted to improve heart function and control abnormal heart rhythms. These include implantable cardioverter defibrillator (ICD), Ventricular assist device (VAD) and pacemaker

NON-INVASIVE MEASURES
Non-invasive methods to treat cardiomyopathy and arrhythmias include septal ablation with alcohol and radiofrequency ablation of the abnormal heart tissue that is causing the symptoms

SURGERY
Septal myomectomy removes a portion of the thickened septum and improves blood flow within the heart

PROGNOSIS
Hypertrophic CMP has the best prognosis although symptoms and severity may vary from case to case. Dilated CMP patients develop heart failure and half the patients die within 2 years. Restrictive CMP has a poor outlook and many persons die within a year of diagnosis