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Cardiac Sarcoidosis

By

L. Brent Mitchell

, MD, Libin Cardiovascular Institute of Alberta, University of Calgary

Last review/revision Jan 2023
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Sarcoidosis is a multisystem, chronic inflammatory/granulomatous disorder that often affects the heart, causing conduction disturbances, bradyarrhythmias, tachyarrhythmias, and sometimes cardiomyopathy. Diagnosis is suspected in patients with known sarcoidosis or young patients who have otherwise unexplained heart block, arrhythmias, or cardiomyopathy. Treatment is corticosteroids and sometimes an implantable cardioverter-defibrillator (ICD).

The inflammatory process in sarcoidosis leads to formation of noncaseating granulomas and fibrosis in any tissue. In cardiac sarcoidosis, the conducting system and/or myocardium are typically involved in patients with clinically apparent cardiac sarcoidosis, but valvular, papillary muscle, and pericardial involvement may also occur. Nearly all patients with cardiac sarcoidosis have involvement of other organs (typically the lungs), but cardiac sarcoidosis may rarely occur in isolation. About 25% of patients with systemic sarcoidosis have cardiac involvement identifiable using imaging techniques, but cardiac involvement is symptomatic in only about 20% of these (5% of all patients with sarcoidosis). The disorder shows marked regional variation in incidence being particularly high in people of Northern European and African descent, being particularly high in African-American women.

The predilection of cardiac sarcoid involvement of the interventricular septum causes atrioventricular (AV) conduction system blocks in many patients with cardiac sarcoidosis. Involvement of the conducting system may cause first-, second-, or third-degree AV block, left anterior or left posterior hemiblock, and left or right bundle branch block. Involvement of the sinus node artery may produce the bradyarrhythmias of sinus nodal dysfunction.

Myocardial involvement may produce tachyarrhythmias, predominantly ventricular tachycardia (VT), but atrial tachycardias, atrial flutter, and atrial fibrillation may also occur.

Most patients with cardiac sarcoidosis are asymptomatic, but the associated bradyarrhythmias and tachyarrhythmias may cause palpitations, syncope, and sometimes cardiac arrest or sudden death. In most patients, disease manifests between the ages of 25 to 60 years. A significant number of deaths resulting from systemic sarcoidosis are due to sudden cardiac death, including in many patients who have had no previous indication of cardiac involvement. Cardiomyopathy may cause any heart failure symptom, including exertional dyspnea, fatigue, and peripheral edema.

Diagnosis of Cardiac Sarcoidosis

  • Clinical suspicion

  • ECG, echocardiography, and sometimes cardiac MRI with late gadolinium enhancement and/or fluorodeoxyglucose (FDG)-positron emission tomography (PET) scan

  • Biopsy of noncardiac tissue that appears affected by systemic sarcoidosis

  • Rarely cardiac biopsy

About half of the patients with clinical manifestations suggestive of cardiac sarcoidosis are already known to have systemic sarcoidosis. Patients with known sarcoidosis and no cardiac symptoms should typically have periodic ECGs and echocardiography to screen for cardiac involvement. If cardiac symptoms, signs, or test abnormalities are present, cardiac MRI with gadolinium should also be done, and also ambulatory ECG monitoring if symptoms suggest a rhythm or conduction disturbance. An FDG-PET scan provides additional information regarding active inflammation and is usually also done.

In patients not yet diagnosed with sarcoidosis, diagnosis of cardiac sarcoidosis is frequently difficult. Cardiac sarcoidosis should be suspected in young patients with heart block, ventricular tachyarrhythmias, and/or heart failure who have no obvious cause. All such patients should have an ECG and an echocardiogram. Patients with an unexplained cardiomyopathy should also have a cardiac MRI.

When findings from these examinations suggest cardiac sarcoidosis or when there is a high suspicion thereof (eg, in young patients with unexplained AV block), further testing for cardiac sarcoidosis (ambulatory ECG monitoring, FDG-PET scan) and further testing for extracardiac sarcoidosis, (chest x-ray, chest CT, whole body FDG-PET scan) is needed. With extensive investigation, most patients with cardiac sarcoidosis will be found to also have extracardiac sarcoidosis.

An international consensus document (1 Diagnosis reference Sarcoidosis is a multisystem, chronic inflammatory/granulomatous disorder that often affects the heart, causing conduction disturbances, bradyarrhythmias, tachyarrhythmias, and sometimes cardiomyopathy... read more ) indicated that the diagnosis of cardiac sarcoidosis requires a cardiac biopsy showing non-caseating granuloma without alternative explanation or an extracardiac tissue biopsy showing non-caseating granuloma without alternative explanation plus one or more of the following without alternative explanation:

  • Corticosteroid-responsive cardiomyopathy or heart block

  • Unexplained reduced left ventricular ejection fraction < 40%

  • Unexplained spontaneous or induced ventricular tachycardia

  • Mobitz type II second-degree AV block or third-degree AV block

  • Cardiac PET scan showing patchy uptake

  • Cardiac MRI showing late gadolinium enhancement

  • Positive gallium uptake on a nuclear scan

Most commonly, the diagnosis is established by extracardiac biopsy in conjunction with suggestive cardiac abnormalities on noninvasive testing. Cardiac biopsy has low sensitivity because the disease process is patchy and pathological tissue may not be sampled. However, sensitivity of cardiac biopsy is improved if it is guided by advanced cardiac imaging techniques or by targeting areas of low voltage.

Diagnosis reference

  • 1. Birnie DH, Sauer WH, Gogun F, et al: HRS Expert Consensus Statement on the Diagnosis and Management of Arrhythmias Associated with Cardiac Sarcoidosis. Heart Rhythm 11:1304–1323, 2014. doi: 10.1016/j.hrthm.2014.03.043

Treatment of Cardiac Sarcoidosis

  • Corticosteroids

  • Sometimes other immunosuppressive drugs

  • Permanent pacemaker and/or implantable cardioverter-defibrillator (ICD)

  • Sometimes antiarrhythmic drugs (avoiding class I drugs)

  • Sometimes transcatheter ablation

  • Heart failure therapy (including transplantation) as required

Standard treatments for sarcoidosis Treatment Sarcoidosis is an inflammatory disorder resulting in noncaseating granulomas in one or more organs and tissues; etiology is unknown. The lungs and lymphatic system are most often affected, but... read more Treatment itself are given, including corticosteroids and sometimes immunosuppressants (eg, methotrexate). These modalities often also ameliorate cardiac abnormalities and should be optimized.

Cardiac treatment is focused on treatment and prevention of arrhythmias. Recommendations for treatment of bradyarrhythmias or tachyarrhythmias follow that for other arrhythmogenic cardiomyopathies including an ICD for prevention of sudden death (see also table Indications for an ICD Indications for Implantable Cardioverter-Defibrillators in Ventricular Tachycardia and Ventricular Fibrillation Indications for Implantable Cardioverter-Defibrillators in Ventricular Tachycardia and Ventricular Fibrillation ). An ICD is recommended for patients with prior sustained VT or resuscitated cardiac arrest or severe right or left ventricular systolic dysfunction. An ICD also may be useful (class IIa indication) for patients with any major risk factor for sudden death, including prior syncope, non-sustained ventricular tachycardia, or moderate right or left ventricular systolic dysfunction.

Specific to cardiac sarcoidosis, a pacemaker is recommended for qualifying AV block even if the AV block reverses spontaneously and, when a permanent pacemaker is indicated (see also table ), an ICD platform is preferred (each a class IIa recommendation). The Heart Rhythm Society cardiac sarcoid consensus document also suggested an ICD should be considered (class IIb recommendation) in patients with cardiac sarcoidosis with a left ventricular ejection fraction in the 35% to 49% range and/or a right ventricular ejection fraction < 40% despite optimal medical therapy for heart failure and use of immunosuppressants in patients with active inflammation (1 Treatment reference Sarcoidosis is a multisystem, chronic inflammatory/granulomatous disorder that often affects the heart, causing conduction disturbances, bradyarrhythmias, tachyarrhythmias, and sometimes cardiomyopathy... read more ).

Antiarrhythmic drugs such as amiodarone and sotalol may be given as necessary to control frequently recurrent ventricular tachycardias and/or other tachyarrhythmias. If drugs (and adequate anti-inflammatory therapy) do not control VT, electrophysiologic studies may be done to identify the origin of the arrhythmia (often a reentrant site) that can then be treated using transcatheter ablation Ablation for Cardiac Arrhythmia The need for treatment of arrhythmias depends on the symptoms and the seriousness of the arrhythmia. Treatment is directed at causes. If necessary, direct antiarrhythmic therapy, including antiarrhythmic... read more .

Heart failure therapy typically includes a beta-blocker (watching for the possibility of worsening AV conduction), an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker, and a mineralocorticoid receptor antagonist. Newer pharmacological treatments for dilated cardiomyopathy, including angiotensin receptor neprilysin inhibitors and sodium-glucose cotransporter 2 inhibitors have been less well studied in patients with sarcoidosis. The frequent coexistence of left bundle branch block in patients with sarcoidosis dilated cardiomyopathy makes cardiac resynchronization therapy Cardiac Resynchronization Therapy (CRT) The need for treatment of arrhythmias depends on the symptoms and the seriousness of the arrhythmia. Treatment is directed at causes. If necessary, direct antiarrhythmic therapy, including antiarrhythmic... read more attractive. Heart transplantation may be considered.

Treatment reference

  • 1. Birnie DH, Sauer WH, Gogun F, et al: HRS Expert Consensus Statement on the Diagnosis and Management of Arrhythmias Associated with Cardiac Sarcoidosis. Heart Rhythm 11:1304–1323, 2014. doi: 10.1016/j.hrthm.2014.03.043

Key Points

  • About 25% of patients with systemic sarcoidosis have cardiac involvement, but only about 5% have cardiac symptoms.

  • Cardiac involvement causes a disproportionate percentage of deaths in patients with sarcoidosis.

  • Diagnosis requires a combination of clinical, electrocardiographic, and imaging findings; cardiac biopsy can be diagnostic but is not usually done.

  • Cardiac manifestations often require a pacemaker/implantable cardioverter-defibrillator (ICD) and sometimes antiarrhythmic drugs.

  • Sarcoidosis itself is treated with corticosteroids and sometimes immunosuppressants.

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