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Overview

What Is Cardiac Sarcoidosis?

Cardiac sarcoidosis is a condition in which sarcoidosis affects the heart. Inflammatory clusters called granulomas can form in heart tissue and may later cause scarring. This inflammation or scarring can affect the heart’s rhythm, electrical conduction system or ability to pump blood. Cardiac sarcoidosis, also called sarcoidosis of the heart, may occur in people with sarcoidosis in other organs or, less commonly, before the condition is recognized elsewhere.

Symptoms

Cardiac Sarcoidosis Symptoms

Cardiac sarcoidosis symptoms vary depending on where inflammation or scarring occurs and how much heart tissue is affected. Some people have no noticeable symptoms, while others develop signs of an abnormal rhythm, reduced pumping function or heart failure.

  • Palpitations (awareness of a fast, slow or irregular heartbeat).
  • Fainting (syncope).
  • Near-fainting (presyncope).
  • Dizziness.
  • Chest pain.
  • Shortness of breath.
  • Fatigue.
  • Leg swelling.
  • Reduced ability to exercise.

Seek urgent care

Urgent symptoms

New fainting, a sustained rapid heartbeat, severe chest pain or severe difficulty breathing requires urgent medical evaluation.

Causes

What Causes Cardiac Sarcoidosis?

The precise cause of sarcoidosis is unknown. An abnormal immune response causes groups of inflammatory cells called granulomas to form in body tissues, and these granulomas can involve the heart. Inflammation may resolve, persist or leave scar tissue that interferes with the heart’s electrical signals or pumping action.

Is Sarcoidosis Genetic?

Inherited susceptibility may contribute to sarcoidosis, but cardiac sarcoidosis is not considered a straightforward single-gene disorder. Infection has not been established as a direct cause. Environmental or occupational exposures may contribute in susceptible people, but they do not prove a specific cause in any individual.

Risk Factors

Risk Factors for Cardiac Sarcoidosis

  • Known sarcoidosis in the lungs, lymph nodes, skin or another organ is the clearest risk context for heart involvement.
  • A previous or current abnormal heart rhythm, conduction problem or unexplained reduction in heart function may raise concern for cardiac sarcoidosis.
  • A family history of sarcoidosis may reflect inherited susceptibility, although it does not predict cardiac involvement with certainty.
  • Sarcoidosis occurs more often in some racial and ethnic populations and commonly begins during adulthood, but it can affect people of different ages and backgrounds.
  • Associated inflammatory or immune-related conditions may occur alongside sarcoidosis, although their effect on cardiac risk is not fully established.

Complications

Complications of Cardiac Sarcoidosis

  • Atrioventricular block can slow or interrupt electrical signals between the heart’s upper and lower chambers.
  • Ventricular arrhythmias are abnormal rhythms arising from the heart’s lower chambers and may be life-threatening.
  • Heart failure can develop when inflammation or scarring weakens the heart’s pumping ability.
  • Cardiomyopathy may cause enlargement, stiffening or weakening of the heart muscle.
  • Inflammation may affect the heart valves or the lining around the heart, called the pericardium.
  • Sudden cardiac arrest can occur when a dangerous rhythm prevents the heart from pumping effectively.

When complications may be urgent

Serious heart symptoms

Fainting, severe palpitations, chest pain or sudden shortness of breath can be associated with serious complications and should be assessed promptly. These symptoms do not always indicate an emergency, but sudden or severe symptoms require urgent medical attention.

Diagnosis

How Is Cardiac Sarcoidosis Diagnosed?

There is no single definitive cardiac sarcoidosis test. Diagnosis combines symptoms or rhythm findings, cardiac imaging, evidence of sarcoidosis elsewhere in the body and exclusion of other causes of heart disease. Doctors may also consider the pattern and location of inflammation or scarring when determining whether sarcoidosis affects the heart.

  • Electrocardiogram records the heart’s electrical activity and may show conduction problems or an abnormal rhythm.
  • Ambulatory rhythm monitoring tracks the heartbeat over hours or days to detect intermittent arrhythmias.
  • Echocardiogram uses ultrasound to assess heart structure, valve function and pumping strength.
  • Cardiac MRI can show heart muscle inflammation, scar tissue and changes in structure or function.
  • FDG-PET imaging can identify areas of active inflammation when the heart is prepared with a specialized diet and fasting plan.
  • Chest imaging may identify lung or lymph-node findings that support sarcoidosis elsewhere in the body.
  • Blood tests may assess inflammation, organ function and alternative explanations, but no blood test alone confirms cardiac sarcoidosis.
  • Biopsy may be considered when appropriate, although sampling can miss patchy disease and a heart biopsy is not always required.

How MRI and PET Help

Cardiac MRI helps identify scar and structural changes, while FDG-PET can highlight areas of active inflammation. The tests answer different questions and may be used together with rhythm testing and evaluation of other organs. Because heart involvement can be patchy, a negative heart biopsy does not always exclude the disease, and clinicians may make a diagnosis using the overall clinical picture.

Treatment & Management

Cardiac Sarcoidosis Treatment and Management

Cardiac sarcoidosis treatment is individualized according to whether inflammation is active, the risk of arrhythmia, the presence of conduction disease, heart function and involvement of other organs. Care often involves a cardiologist, an electrophysiologist and a specialist familiar with sarcoidosis. The goals are to control inflammation, protect heart function and reduce the risk of dangerous rhythms.

  • Corticosteroids are often used to reduce active inflammation and may be adjusted according to response and side effects.
  • Steroid-sparing immunosuppressants may be added or used to reduce long-term corticosteroid exposure in selected patients.
  • Medicines for heart failure or arrhythmias help manage reduced pumping function, fluid retention or abnormal rhythms.
  • A pacemaker may be needed when inflammation or scarring causes significant conduction block or a persistently slow heartbeat.
  • An implantable cardioverter-defibrillator may be recommended for selected patients at risk of life-threatening ventricular arrhythmias.
  • Catheter ablation can treat some recurrent arrhythmias when medicines are not enough.
  • Heart transplantation may be considered for a small number of people with advanced, otherwise uncontrolled heart failure.

Long-Term Management

Long-term care may include repeat rhythm assessment, electrocardiograms, ambulatory monitoring and follow-up imaging. Medicines require monitoring for effectiveness and side effects, and activity guidance should be based on cardiac risk rather than symptoms alone. Coordination between cardiology, electrophysiology and sarcoidosis specialists helps adjust treatment as inflammation, rhythm findings or heart function change.

Medication safety

Treatment changes require specialist guidance

Do not start, stop or taper corticosteroids or other immunosuppressive medicines without medical guidance. Stopping treatment suddenly or changing the dose without supervision can increase risks.

Outlook and Prognosis

Outlook and Prognosis

Some people respond well to treatment and have stable heart function, while others develop persistent or recurrent inflammation, scarring or rhythm problems. The outlook for cardiac sarcoidosis varies substantially between individuals. Early recognition, appropriate treatment and regular monitoring can help reduce the risk of serious complications.

  • Ventricular function affects outlook because a weakened pumping ability can increase the risk of heart failure and arrhythmias.
  • The extent and location of scar tissue can influence electrical stability and how well the heart contracts.
  • A history of ventricular arrhythmias or other serious rhythm problems may indicate higher risk.
  • Response to immunosuppression helps show whether active inflammation is being controlled.
  • Adherence to follow-up allows clinicians to detect changes in rhythm, inflammation or heart function earlier.

When Should You See a Doctor

When Should You See a Doctor?

  • Arrange medical evaluation for unexplained fainting or near-fainting.
  • Discuss recurrent palpitations, especially if they are new, prolonged or associated with dizziness.
  • Seek evaluation for new or worsening breathlessness, particularly during usual activities or when lying down.
  • Report new chest discomfort or pressure to a healthcare professional.
  • Arrange assessment for new swelling in the legs, ankles or abdomen.
  • Contact a clinician if known sarcoidosis is accompanied by new palpitations, fainting, breathlessness or chest symptoms.

Get emergency help

Emergency symptoms

Call emergency services for severe chest pain, severe breathing difficulty, collapse, fainting with ongoing symptoms or a sustained rapid or irregular heartbeat.

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