cardiovascular disorders
Cardiac Sarcoidosis
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 ( Diagnosis reference ) 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. 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 Rhythm11:1304–1323, 2014. doi: 10.1016/j.hrthm.2014.03.043 