Sarcoidosis is a multisystem granulomatous disease of unknown etiology which primarily involves the pulmonary and lymph node systems but which can also affect the heart. The prevalence of cardiac sarcoidosis varies from 25% in postmortem studies  to almost 40% in a recent study of ambulatory extracardiac sarcoidosis patients. Confirmed cardiac involvement carries a poor prognosis.  This, combined with the prevalence of asymptomatic disease and the risk of sudden cardiac death (which may be the first mode of presentation) makes an imaging-based diagnosis particularly valuable. Although recent advances in imaging technology such as PET or MRI facilitate earlier detection, they may not be universally available or suitable for all patients. Two-dimensional (2D) transthoracic echocardiography remains the first line initial imaging screening tool in extracardiac sarcoid patients as well as providing a quick, cost-effective method to monitor systolic and diastolic function in known cardiac sarcoidosis. In addition, novel adjunctive echocardiographic tools are being developed which may enable increased sensitivity of echocardiography for early, focal disease detection in the future.
Sarcoid granulomas can involve any part of the heart, but most frequently involve the myocardium, where the most commonly affected regions are the LV free wall and basal interventricular septum, the right ventricle and the atrial walls.  Involvement can manifest as diffuse microscopic focal infiltrates or larger nodules, edema, fibrosis or scarring. Clinical features of cardiac involvement only occur in 5% of sarcoidosis patients and depend on the location and extent of granulomatous involvement, and on the activity of the disease. Most common presenting features are conduction abnormalities, congestive heart failure and ventricular arrhythmias. The diagnosis should always be considered in unexplained sustained 2nd or 3rd degree atrioventricular block in young adults (<55 years) or sustained monomorphic ventricular tachycardia in the setting of dilated cardiomyopathy.
In 2006, the previous 1993 Japanese Ministry of Health guidelines for the diagnosis of cardiac sarcoidosis were revised, although they have not been prospectively validated.  The current updated guidelines incorporate newer imaging modalities such as gadolinium enhanced cardiac magnetic resonance imaging and gallium-67 scintigraphy but also include several diagnostic criteria that may be illustrated by echocardiography as shown in Table 1.
Echocardiography in Sarcoid Heart Disease
Two-dimensional transthoracic echocardiographic abnormalities have been reported in 14-56%  of sarcoidosis patients but may be subtle until the later stages of the disease. Most commonly described are LV systolic dysfunction, wall motion abnormalities and abnormal septal thickness, but diastolic dysfunction, ventricular aneursym, valvular abnormalities, right ventricular dysfunction and pericardial abnormalities can also occur. All are detailed below. A speckled or snowstorm pattern due to areas of bright echoes reflecting granulomatous infiltration may also be seen.
Abnormal Septal Wall Thickness
This is the most common echocardiographic presentation of cardiac sarcoidosis and can manifest as abnormal thinning or thickening. Localized thinning of the basal interventricular septum, as depicted in Figure 1, has been detected in up to 90% of patients with cardiac sarcoidosis. 
Ventricular aneurysm is another characteristic finding in cardiac sarcoidosis, most commonly affecting the infero-posterior wall as shown in Figure 2. They occur due to direct myocardial involvement by the sarcoid granulomas. They can be distinguished from ischemic aneurysms by the fact that they do not follow typical coronary artery distributions.
LV Systolic Dysfunction
Dilated cardiomyopathy has been documented in up to 32% of patients with known cardiac sarcoidosis.  Associated LV dilatation, as depicted in Figure 3, is an independent predictor of mortality.  LV systolic dysfunction may be segmental/regional due to patchy involvement of the granulomas or global, due to diffuse involvement of the myocardium and/or secondary to valvular regurgitation. Regional wall motion abnormalities in cardiac sarcoidosis may preferentially affect the anterior and apical segments. 
LV Diastolic Dysfunction
LV diastolic dysfunction, mainly impaired relaxation, may be the earliest sign of granulomatous involvement of the myocardium, occurring in up to 14% of those with pulmonary sarcoidosis.  Early mitral annular tissue velocity of the septal wall has also been shown to be lower in pulmonary sarcoidosis patients compared to controls. 
Valve leaflets may also be affected, leading to regurgitation. Although any of the 4 cardiac valves may be affected, the most common valvular lesion in cardiac sarcoidosis is mitral regurgitation.  It may occur due to left ventricular dysfunction and/or direct granulomatous involvement of the valve leaflets. An example of significant mitral regurgitation in a patient with cardiac sarcoidosis is shown in Figure 3 (panels D-F).
Right Ventricular Dysfunction
This occurs most commonly secondary to pulmonary hypertension resulting from sarcoid lung involvement. The frequency of pulmonary hypertension in sarcoidosis as evaluated by Doppler echocardiography was found in 1 study to be up to 5.7%; advanced radiographic stage and decreased lung volumes were risk factors  The right ventricle may also be directly involved by the granulomatous inflammation leading to regional or global dysfunction.
Pericardial effusions are not infrequent in cardiac sarcoidosis, occurring in up to 19% of patients.  They are usually hemodynamically insignificant, as shown in Figure 3 (panel D), but associated cardiac tamponade has been reported. Constrictive pericarditis may rarely occur. 
Advanced Echocardiography in Sarcoid Heart Disease
Standard 2D echo-Doppler may lack sensitivity to detect early, mild or focal cardiac involvement. Newer adjunctive echocardiographic techniques may provide increased sensitivity to detect subtle, patchy disease. Two such techniques are detailed below.
Ultrasonic Tissue Characterisation
The cycle dependent variation of myocardial integrated backscatter analysis non-invasively measures acoustic properties of the myocardium and can aid differentiation between affected and normal myocardium. It has been shown to be decreased in the basal septum in patients with cardiac involvement even in the absence of two- dimensional echocardiographic abnormalities. 
Tissue Doppler (TDI) derived longitudinal strain has recently been explored as both a diagnostic modality and an inexpensive and sensitive method to monitor response to therapy.  Figure 4 illustrates similar findings using this technique in a patient 1 year before subsequent diagnosis with cardiac sarcoidosis. In the future, evolving deformational techniques may provide further non-invasive, non-radiating and sensitive tools to detect early and/or regional granulomatous infiltration of the myocardium in sarcoid heart disease.
- ↑ Perry A, Vuitch F. Causes of death in patients with sarcoidosis. A morphologic study of 38 autopsies with clinicopathologic correlations. Arch Pathol Lab Med. 1995 Feb;119(2):167-72.
- ↑ Mehta D, Lubitz SA, Frankel Z, Wisnivesky JP, Einstein AJ, Goldman M, et al. Cardiac involvement in patients with sarcoidosis: diagnostic and prognostic value of outpatient testing. Chest. 2008 Jun;133(6):1426-35.
- ↑ 3.0 3.1 Yazaki Y, Isobe M, Hiroe M, Morimoto S, Hiramitsu S, Nakano T, et al. Prognostic determinants of long-term survival in Japanese patients with cardiac sarcoidosis treated with prednisone. Am J Cardiol. 2001 Nov 1;88(9):1006-10.
- ↑ 4.0 4.1 Roberts WC, McAllister HA, Jr., Ferrans VJ. Sarcoidosis of the heart. A clinicopathologic study of 35 necropsy patients (group 1) and review of 78 previously described necropsy patients (group 11). Am J Med. 1977 Jul;63(1):86-108.
- ↑ Sekhri V, Sanal S, Delorenzo LJ, Aronow WS, Maguire GP. Cardiac sarcoidosis: a comprehensive review. Arch Med Sci. 2011 Aug;7(4):546-54.
- ↑ Soejima K, Yada H. The work-up and management of patients with apparent or subclinical cardiac sarcoidosis: with emphasis on the associated heart rhythm abnormalities. J Cardiovasc Electrophysiol. 2009 May;20(5):578-83.
- ↑ Youssef G, Beanlands RS, Birnie DH, Nery PB. Cardiac sarcoidosis: applications of imaging in diagnosis and directing treatment. Heart. 2011 Dec;97(24):2078-87.
- ↑ Sharma OP, Maheshwari A, Thaker K. Myocardial sarcoidosis. Chest. 1993 Jan;103(1):253-8.
- ↑ 9.0 9.1 Sun BJ, Lee PH, Choi HO, Ahn JM, Seo JS, Kim DH, et al. Prevalence of echocardiographic features suggesting cardiac sarcoidosis in patients with pacemaker or implantable cardiac defibrillator. Korean Circ J. 2011 Jun;41(6):313-20.
- ↑ Chapelon-Abric C, de Zuttere D, Duhaut P, Veyssier P, Wechsler B, Huong DL, et al. Cardiac sarcoidosis: a retrospective study of 41 cases. Medicine (Baltimore). 2004 Nov;83(6):315-34.
- ↑ Yazaki Y, Isobe M, Hiramitsu S, Morimoto S, Hiroe M, Omichi C, et al. Comparison of clinical features and prognosis of cardiac sarcoidosis and idiopathic dilated cardiomyopathy. Am J Cardiol. 1998 Aug 15;82(4):537-40.
- ↑ Fahy GJ, Marwick T, McCreery CJ, Quigley PJ, Maurer BJ. Doppler echocardiographic detection of left ventricular diastolic dysfunction in patients with pulmonary sarcoidosis. Chest. 1996 Jan;109(1):62-6.
- ↑ Aydin Kaderli A, Gullulu S, Coskun F, Yilmaz D, Uzaslan E. Impaired left ventricular systolic and diastolic functions in patients with early grade pulmonary sarcoidosis. Eur J Echocardiogr. 2010 Dec;11(10):809-13.
- ↑ Fleming HA, Bailey SM. Sarcoid heart disease. J R Coll Physicians Lond. 1981 Oct;15(4):245-6, 9-53.
- ↑ Handa T, Nagai S, Miki S, Fushimi Y, Ohta K, Mishima M, et al. Incidence of pulmonary hypertension and its clinical relevance in patients with sarcoidosis. Chest. 2006 May;129(5):1246-52.
- ↑ Kinney E, Murthy R, Ascunce G, Donohoe R, Zelis R. Pericardial effusions in sarcoidosis. Chest. 1979 Oct;76(4):476-8.
- ↑ Garrett J, O'Neill H, Blake S. Constrictive pericarditis associated with sarcoidosis. Am Heart J. 1984 Feb;107(2):394.
- ↑ Hyodo E, Hozumi T, Takemoto Y, Watanabe H, Muro T, Yamagishi H, et al. Early detection of cardiac involvement in patients with sarcoidosis by a non-invasive method with ultrasonic tissue characterisation. Heart. 2004 Nov;90(11):1275-80.
- ↑ Lo A, Foder K, Martin P, Younger JF. Response to steroid therapy in cardiac sarcoidosis: insights from myocardial strain. Eur Heart J Cardiovasc Imaging. 2012 Feb;13(2):E3.
- Kim JS, Judson MA, Donnino R, Gold M, Cooper LT, Jr., Prystowsky EN, et al. Cardiac sarcoidosis. Am Heart J. 2009 Jan;157(1):9-21.
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