In short
Cardiac sarcoidosis is a rare condition where tiny clumps of immune cells called granulomas form in your heart, causing inflammation that can disrupt normal heart function and lead to serious complications if left untreated.
What Is Cardiac Sarcoidosis?
Cardiac sarcoidosis is a condition in which your immune system triggers inflammation that harms your heart. Clumps of immune cells called granulomas (tiny clusters of cells) form in your heart. Over time, these granulomas may cause scarring. The scars can damage your heart muscle, interfere with your heart's electrical activity, and cause abnormal heart rhythms.
This condition is a less common form of a disease called sarcoidosis, which is a disorder that can affect many organs in the body. Most people with sarcoidosis have granulomas in their lungs. However, it's possible to have them in your heart as well, and not know until testing reveals them. Experts believe that up to 1 in 4 people with sarcoidosis have heart involvement.
- Heart
- Heart muscle (myocardium)
Cardiac sarcoidosis is a rare condition. Approximately 25% of patients with general sarcoidosis have cardiac disease involvement, and about 25% of patients have isolated cardiac sarcoidosis, meaning the condition affects only the heart and no other organs.
Symptoms
Many patients with cardiac sarcoidosis will be free of symptoms. It's also possible not to feel any symptoms of sarcoidosis in your heart. Whether you have symptoms depends on where the granulomas form and how much inflammation they cause.
When symptoms do occur, cardiac sarcoidosis can disrupt normal heart function and cause symptoms like:
- Chest pain or tightness
- Coughing
- Fainting
- Fatigue
- Heart palpitations (feeling like your heart is racing or pounding)
- Shortness of breath
- Swelling in your legs
- Dizziness
The clinical presentation of cardiac sarcoidosis is highly variable. Patients frequently present with symptoms of heart failure, conduction abnormalities (problems with the heart's electrical system), ventricular arrhythmias (abnormal heart rhythms), or in rare cases, sudden cardiac death. The most common presentations are problems with the heart's conduction system and heart failure.
Causes and Risk Factors
Experts don't fully understand what causes cardiac sarcoidosis. They believe it's likely a mix of your genes and your environment. Cardiac sarcoidosis is due to an overactive immune system. The condition results from a combination of environmental, genetic, and inflammatory factors causing the accumulation of granulomas in the heart.
Certain genes may make your immune system more likely to overreact to triggers like mold, insecticides, silica dust, or bacteria — causing immune cells to cluster in your heart. Doctors are unsure what causes this reaction, but it might be related to inhaling biological contaminants. Risk factors include exposure to bacteria, viruses, pesticides, fumes, and mold.
You have a higher risk of cardiac sarcoidosis if someone in your biological family has the condition.
Possible Complications
Cardiac sarcoidosis can keep your heart from working as it should. For example, inflammation or scars may block electrical signals from getting where they need to be. This can cause your heart to beat out of sync. Or your heart may be unable to pump enough blood to meet your body's needs. Without treatment, these issues can be life-threatening.
As the inflammation in the heart progresses, it can lead to serious complications including:
- Atrial fibrillation (irregular heartbeat in the upper chambers of the heart)
- Heart block (abnormally slow heart rhythm where electrical signals are delayed or blocked)
- Heart failure (when the heart cannot pump enough blood)
- Ventricular fibrillation (dangerously fast and irregular heartbeat in the lower chambers)
- Ventricular tachycardia (dangerously fast heart rhythm)
- Sudden cardiac death
Cardiac sarcoidosis is a rare condition with a generally poor prognosis. The left ventricular ejection fraction (a measurement of how well the heart pumps blood) is the most important predictor of mortality in cardiac sarcoidosis.
How Is It Diagnosed?
Diagnosing cardiac sarcoidosis is often challenging because there is no single diagnostic test for the condition, and the clinical presentation is variable. Cardiac sarcoidosis can mimic other conditions and go undiagnosed for years. Sarcoidosis is sometimes considered a diagnosis of exclusion because there is no single diagnostic laboratory, radiologic, or other test.
To diagnose cardiac sarcoidosis, your provider will give you a physical exam and ask about your symptoms. They'll review your health history and ask about any biological family members who have sarcoidosis. You'll also need some tests. These allow your provider to check for signs of heart inflammation or scarring. Testing also helps rule out other conditions.
Possible tests include:
- Blood tests
- Chest X-ray
- Electrocardiogram (EKG) — a test that records the electrical activity of your heart
- Echocardiogram — an ultrasound of your heart
- Heart MRI
- Holter monitor — a portable device that records your heart rhythm
- Heart PET scan
The exact tests you need can vary. If you've already been diagnosed with sarcoidosis elsewhere in your body, your provider may want to "screen" for it in your heart. This may happen even without heart symptoms. If you have symptoms, you'll need more extensive testing.
The most accurate way to diagnose cardiac sarcoidosis is with a biopsy of the heart, though this has a low sensitivity for detection of granulomas due to the patchy nature of the disease. Providers usually don't use biopsies to diagnose cardiac sarcoidosis. While endomyocardial biopsy (taking a small sample of heart tissue) has a high specificity for cardiac sarcoidosis, it is invasive and insensitive. As an alternative, a combination of sarcoidosis in other organs, clinical symptoms, and imaging studies can be used to diagnose cardiac sarcoidosis.
These imaging studies may include a cardiac MRI and/or a type of nuclear imaging study called Positron Emission Tomography (PET). Together, these imaging studies can detect both active inflammation and scar due to prior inflammation.
Early diagnosis gives you the best chance to manage symptoms and protect your heart.
Treatment Options
There is no known cure for sarcoidosis, though the condition can clear up on its own. Treatment is focused on helping you manage your symptoms and improve your quality of life. The goal of treatment is to target and reduce inflammation.
Medicines can reduce the inflammation in your heart that's causing the problem. Treatment can also help manage complications like arrhythmias and heart failure.
Medication Therapy
The first line of therapy is with corticosteroids (medications that reduce inflammation), such as prednisone. In addition, you may be advised to take a second immunosuppressive medication such as mycophenolate mofetil, methotrexate, or azathioprine. These medications are collectively called steroid-sparing agents.
In cases of steroid-resistant cardiac sarcoidosis, monoclonal antibodies (specialized proteins that target specific parts of the immune system) such as TNF-alpha inhibitors (infliximab, adalimumab) may be recommended to treat the ongoing inflammation. After this therapy is completed, most patients will remain on some form of immunosuppression for the rest of their lives.
The available treatments for cardiac sarcoidosis are nonspecific and may cause adverse systemic effects. However, early diagnosis and intervention can improve outcomes for patients with this uncommon condition.
Device Therapies
Cardiac sarcoidosis can present with a variety of dangerous heart rhythms. These include heart block (abnormally slow heart rhythm) or ventricular tachycardia/ventricular fibrillation (dangerously fast heart rhythms). In such cases, the implantation of a cardiac pacemaker and/or implantable cardioverter defibrillator (ICD) (a device that monitors heart rhythm and delivers shocks if needed) by a cardiac electrophysiologist can help manage these conditions.
Advanced Therapies
In cases where inflammation does not completely resolve or where there is a large scar burden in the heart, cardiac sarcoidosis may lead to progressive end-stage heart failure. Advanced heart failure therapies such as implantation of a mechanical pump called a left ventricular assist device (LVAD) or heart transplantation may be considered.
Outlook
There's no single staging system for cardiac sarcoidosis. But providers may use terms like "early stage" or "advanced stage" to describe how much tissue damage they see.
Imaging can help your provider see how far the condition has progressed. Early on, inflammation in your heart may not cause lasting damage. But over time, scars can form. Ideally, providers diagnose this condition in the early stages, before scars damage your heart.
Cardiac sarcoidosis is a rare condition with a generally poor prognosis. However, early diagnosis and intervention can improve outcomes. The left ventricular ejection fraction is the most important predictor of mortality in cardiac sarcoidosis.
