Restrictive Cardiomyopathy

A healthy heart expands flexibly to take in blood, then pumps it throughout the body. In restrictive cardiomyopathy, the muscle of the heart's lower chambers (ventricles) becomes stiff and cannot expand well. Pressure inside the heart rises, blood backs up into the lungs and the body, and both upper chambers of the heart (atria) become enlarged. Pumping strength is often still normal in the early stages, so this condition is one of the causes of heart failure with preserved ejection fraction.

Because the ventricles cannot hold enough blood, the amount of blood pumped with each beat becomes small, especially when the heart beats fast during activity. That is why shortness of breath and fatigue are often first felt during movement.

A Rare Type of Cardiomyopathy

Restrictive cardiomyopathy is a rare type of cardiomyopathy. The 2023 European Society of Cardiology (ESC) guidelines use this term for a stiff heart with normal or small ventricles and walls that are not thickened. Storage diseases such as amyloidosis can cause similar stiffness, but usually with thickened walls. This group of storage diseases is covered on the Infiltrative Cardiomyopathy page.

Varied Causes

Causes can include changes in the genes for heart muscle proteins, especially in children and young adults; buildup of protein, iron, or other substances in the heart muscle; scar tissue after chest radiation or certain cancer drugs; and diseases of the heart's inner lining, such as endomyocardial fibrosis and inflammation caused by high levels of eosinophils, a type of white blood cell. In some people no cause is found, and this is called idiopathic.

Similar to Constrictive Pericarditis

Its symptoms and test results are very similar to those of constrictive pericarditis, a stiffening and thickening of the sac that surrounds the heart. Telling the two apart is important because constrictive pericarditis can be treated with surgery, while restrictive cardiomyopathy cannot. That condition is covered on the Constrictive Pericarditis page.

Treatment Approach

Treatment focuses on controlling fluid with carefully adjusted water pills (diuretics), controlling heart rhythm, preventing blood clots, and treating the cause when there is one, such as amyloidosis or iron overload. In advanced stages, a heart transplant may be considered. An overview of this family of diseases is covered on the Cardiomyopathy page.

Your doctor asks about your symptoms, your history of cancer treatment and blood disorders, and any heart disease in your family, then checks for signs of congestion such as bulging neck veins, an enlarged liver, and swelling. An ECG and an NT-proBNP test are the first steps.

Echocardiography shows enlarged atria, ventricles that are not enlarged, and a stiff filling pattern. Cardiac MRI assesses the heart muscle tissue and helps find the cause, such as amyloidosis, iron deposits, or scar tissue. To distinguish the condition from constrictive pericarditis, your doctor may perform cardiac catheterization to measure the pressures on both sides of the heart at the same time. If the cause is still unclear, a heart muscle biopsy, a bone scan for transthyretin amyloidosis, blood and urine protein tests, and genetic testing may be considered. The results of all these tests determine whether there is a specific treatment for the cause.

Restrictive cardiomyopathy develops slowly, so early symptoms are easily mistaken for ordinary tiredness. Go to the emergency room right away if you have severe shortness of breath at rest, fainting, persistent chest pain, or signs of a stroke. Make an appointment if you experience any of the following:

• Shortness of breath or tiring easily that happens more and more often
• Leg or abdominal swelling that does not go away
• A pounding or irregular-feeling heartbeat
• Shortness of breath after past chest radiation or chemotherapy
• A family member with cardiomyopathy, amyloidosis, or sudden death at a young age
• A child with frequent shortness of breath that does not improve with asthma medicine