Cardiomyopathy- Causes, Diagnosis, Treatment

Cardiomyopathy is a disease of the heart muscle. There are three main types of cardiomyopathy — dilated, hypertrophic and restrictive — all of which affect your heart’s muscle, often making it difficult to pump blood and deliver it to the rest of your body. There are many causes of cardiomyopathy, including coronary artery disease and valvular heart disease.

Cardiomyopathy can be treated. The type of treatment you’ll receive depends on which type of cardiomyopathy you have and how serious it is. Your treatment may include medications, surgically implanted devices or, in severe cases, a heart transplant.

Causes

Most of the time, the cause of the cardiomyopathy is unknown. In some people, however, doctors are able to identify some contributing factors. Possible causes of cardiomyopathy include:

  • Long-term high blood pressure
  • Heart valve problems
  • Heart tissue damage from a previous heart attack
  • Chronic rapid heart rate
  • Metabolic disorders, such as thyroid disease or diabetes
  • Nutritional deficiencies of essential vitamins or minerals, such as thiamin (vitamin B-1), selenium, calcium and magnesium
  • Pregnancy
  • Excessive use of alcohol over many years
  • Abuse of cocaine or antidepressant medications, such as tricyclic antidepressants
  • Use of some chemotherapy drugs to treat cancer
  • Certain viral infections, which may injure the heart and trigger cardiomyopathy

Hemochromatosis is a disorder in which your body doesn’t properly metabolize iron, causing it to build up in various organs, including your heart muscle. This can lead to a weakening of the heart muscle, resulting in dilated cardiomyopathy.

The three types of cardiomyopathy are:

  • Dilated cardiomyopathy. This is the most common type of cardiomyopathy. In this disorder, your heart’s main pumping chamber — the left ventricle — becomes enlarged (dilated), its pumping ability becomes less forceful, and blood doesn’t flow as easily through the heart. Although this type can affect people of all ages, it occurs most often in middle-aged people, and is more likely to affect men. Some people with dilated cardiomyopathy may have a family history of the condition.
  • Hypertrophic cardiomyopathy. This type involves abnormal growth or thickening of your heart muscle, particularly affecting the muscle of your heart’s main pumping chamber. As thickening occurs, the heart tends to stiffen and the size of the pumping chamber may shrink, interfering with your heart’s ability to deliver blood to your body. Hypertrophic cardiomyopathy can develop at any age, but the condition tends to be more severe if it becomes apparent during childhood. Most affected people have a family history of the disease, and some genetic mutations have been linked to hypertrophic cardiomyopathy.
  • Restrictive cardiomyopathy. The heart muscle in people with restrictive cardiomyopathy becomes rigid and less elastic, meaning the heart can’t properly expand and fill with blood between heartbeats. While restrictive cardiomyopathy can occur at any age, it most often tends to affect older people. It’s the least common type of cardiomyopathy and can occur for no known reason (idiopathic). The condition may also be caused by diseases elsewhere in the body that affect the heart, such as amyloidosis, a rare condition in which abnormal proteins present in the blood are deposited into the heart.

Symptoms

Some people who develop cardiomyopathy may have no signs and symptoms in the early stages of the disease. But as the condition advances, signs and symptoms usually appear. Signs and symptoms of cardiomyopathy may include:

  • Breathlessness with exertion or even at rest
  • Swelling of the legs, ankles and feet
  • Bloating (distention) of the abdomen with fluid
  • Fatigue
  • Irregular heartbeats that feel rapid, pounding or fluttering
  • Dizziness, lightheadedness and fainting

No matter what type of cardiomyopathy you have, signs and symptoms tend to get worse unless treated. In certain people, this worsening happens quickly; while in others, the disease may not worsen for a long time.

Diagnosis

Your doctor will conduct a physical examination, take a personal and family medical history, and ask when your symptoms occur — for example, whether exercise brings on your symptoms. If your doctor thinks you have cardiomyopathy, you may need to undergo several tests to confirm the diagnosis. These tests may include:

  • Chest X-ray. An image of your heart will show whether it’s enlarged.
  • Echocardiogram. An echocardiogram uses sound waves to produce images of the heart. Your doctor can use these images to examine the size of your heart and its motions as it beats.
  • Electrocardiogram (ECG). In this noninvasive test, electrode patches are attached to your skin to measure electrical impulses from your heart. An ECG can show disturbances in the electrical activity of your heart, which can detect abnormal heart rhythms and areas of injury.
  • Cardiac catheterization and biopsy. In this procedure, a thin tube (catheter) is inserted in your groin and threaded through your blood vessels to your heart, where a small sample (biopsy) of your heart can be extracted for analysis in the laboratory. Pressure within the chambers of your heart can be measured to see how forcefully blood pumps through your heart. Pictures of the arteries of the heart can be taken during the procedure (coronary angiogram) to ensure that you do not have any blockage.
  • Blood tests. One blood test can measure brain natriuretic peptide (BNP), a protein produced in your heart. Your blood level of BNP rises when your heart is subjected to the stress of heart failure, a common complication of cardiomyopathy.A variety of other blood tests may be done, including those to check your kidney function and look for anemia and thyroid problems. Your iron level may be measured. Having too much may indicate an iron overload disorder called hemochromatosis. Accumulating too much iron in your heart muscle can weaken it. Early diagnosis and treatment can prevent the progression of this serious disease.

Treatment

The overall goals of treatment for cardiomyopathy are to manage your signs and symptoms, prevent your condition from worsening, and reduce your risk of complications. Treatment varies by which of the major types of cardiomyopathy you have.

Dilated cardiomyopathy
If you’re diagnosed with dilated cardiomyopathy, your doctor may recommend medications, surgically implanted devices, or a combination of both. The medications you may be prescribed include:

  • Angiotensin-converting enzyme (ACE) inhibitors to improve your heart’s pumping capability, such as enalapril (Vasotec), lisinopril (Zestril, Prinivil), ramipril (Altace) or captopril (Capoten)
  • Angiotensin receptor blockers (ARBs) for those who can’t take ACE inhibitors, such as losartan (Cozaar) and valsartan (Diovan)
  • Beta blockers to improve heart function, such as carvedilol (Coreg) and metoprolol (Lopressor, Toprol XL)

Another option for some people with dilated cardiomyopathy is a special pacemaker that coordinates the contractions between the left and right ventricle (biventricular pacing). In people who may be at risk of serious arrhythmias, drug therapy or an implantable cardioverter-defibrillator (ICD) may be options. ICDs are small devices — about the size of a box of matches — implanted in your chest to continuously monitor your heart rhythm and deliver electrical shocks when needed to control abnormal, rapid heartbeats. The devices can also work as pacemakers.

Hypertrophic cardiomyopathy
Your doctor may recommend beta blockers to relax your heart, slow its pumping action and stabilize its rhythm. These medications include Lopressor or calcium channel blockers, such as verapamil (Calan, Isoptin).

In some cases, your doctor may recommend a pacemaker or an ICD. In advanced cases of hypertrophic cardiomyopathy, a surgeon may remove a portion of the thickened muscle wall that blocks normal blood flow. This procedure, called septal myotomy-myectomy, can reduce symptoms in most cases.

Your doctor may also recommend a new therapy called alcohol ablation. This nonsurgical procedure, which uses injected alcohol to destroy extra heart muscle, may reduce muscle thickening and improve blood flow.

Restrictive cardiomyopathy
Treatment for restrictive cardiomyopathy focuses on improving symptoms. Your doctor will recommend you pay careful attention to your salt and water intake and monitor your weight daily. Your doctor may also recommend you take diuretics if sodium and water retention becomes a problem. You may be prescribed medications to lower your blood pressure and control fast or irregular heart rhythms.

Many of the medications that doctors prescribe for cardiomyopathy may have side effects. Be sure to discuss these possible side effects with your doctor before taking any of these drugs.

Heart transplantation
If you have severe cardiomyopathy and medications can’t control your symptoms, a heart transplant may be an option. Because of the shortage of donor hearts, even people who are critically ill may have a long wait before having a heart transplant. In some cases, a mechanical heart assist device can help critically ill people as they wait for an appropriately matched donor. These devices, known as ventricular assist devices (VADs), can support the circulation for a prolonged period and may allow you to live outside the hospital while you wait. In some people who aren’t candidates for a heart transplant, VAD therapy may provide long-term support.

Complications

Having cardiomyopathy may produce the following complications:

  • Heart failure. Heart failure means your heart can’t pump enough blood to meet your body’s needs. The thickened, stiffened or weakened heart muscle due to cardiomyopathy can become unable to pump or can obstruct blood flow out of the heart.
  • Blood clots. Any of the types of cardiomyopathy may make you more susceptible to blood clots in your heart. If clots are pumped out of the heart and enter your circulatory system, they can block the blood flow to vital organs, including your heart and brain. If clots develop on the right side of your heart, they may travel to your lungs. To reduce your risk, your doctor may prescribe a blood thinner (anticoagulant medication), such as aspirin, clopidogrel (Plavix) or warfarin (Coumadin).
  • Heart murmur. Because people with dilated cardiomyopathy have an enlarged heart, two of the heart’s four valves — the mitral and tricuspid valves — may not close properly, leading to a backflow of blood. This flow creates sounds called heart murmurs. Heart murmurs are not necessarily harmful, but they should be monitored by your doctor.
  • Cardiac arrest and sudden death. All forms of cardiomyopathy can lead to abnormal heart rhythms. Some of these heart rhythms are too slow to sustain the circulation, and some are too fast to allow the heart to beat properly. In either case, these abnormal heart rhythms can result in fainting or, in some cases, sudden death from a complete cessation of heartbeats, called cardiac arrest.

Prevention

In most cases you can’t prevent cardiomyopathy. Let your doctor know if you have a family history of the condition. If cardiomyopathy is diagnosed early, treatments may prevent the disease from worsening.

You can help reduce your chance of heart failure by avoiding some of the conditions that can contribute to a weak heart, including the abuse of alcohol or cocaine, or not getting enough vitamins and minerals. Controlling high blood pressure with diet and exercise also prevents many people from developing heart failure later in life.