Cardiac sarcoidosis

Cardiac sarcoidosis

എന്താണ് കാർഡിയാക് സാർകോയിഡോസിസ്?

Sarcoidosis is a multi-system inflammatory disorder characterized by non caseating granulomas. Worse prognosis has been associated with cardiac involvement in sarcoidosis and be seen in about one fourth of cases. Sarcoidosis is an immunologically mediated disease which commonly involves the skin, lymph nodes, lungs, eyes and central nervous system [1]. Clinical cardiac involvement may be as low as 5% while autopsy series have reported 25% cardiac involvement [2,3]. Exact etiology of sarcoidosis is still unsettled.

In a study of 1235 patients who underwent endomyocardial biopsy for unexplained cardiomyopathy at the Johns Hopkins Hospital between 1982 and 1997, 28 had a clinical diagnosis of sarcoidosis. Seven of these 28 patients and 3 with other initial diagnosis had cardiac sarcoidosis on endomyocardial biopsy. 20 of those with clinical diagnosis had negative biopsy results, highlighting the difficulty of confirming cardiac sarcoidosis by biopsy. There were 7 deaths with a median survival of 2.34 years in that group. The odds ratio of death was higher in those with a positive biopsy but did not reach statistical significance [3].

Fluorodeoxyglucose positron emission tomography (FDG PET) and magnetic resonance imaging (MRI) have been shown to be important imaging modalities for the diagnosis of cardiac sarcoidosis. One study had data on 21 consecutive patients with FDG PET, MRI and serum angiotensin converting enzyme levels. Eight of these were diagnosed as having cardiac sarcoidosis according to the Japanese Ministry of Health and Welfare Guidelines for Diagnosing Cardiac Sarcoidosis. But positive findings on one of the imaging modalities were noted in 16 cases. Presence of positive findings on FDG PET was associated with elevated serum ACE levels while this association was not seen with MRI [4].

Though the characteristic non-caseating granulomas can involve any part of the heart, left ventricle is the most commonly affected chamber. Successive histological stages show edema, granulomatous inflammation and fibrosis leading to post inflammatory scarring [1].

Important clinical manifestations of cardiac sarcoidosis include conduction abnormalities, arrhythmias, congestive heart failure and sudden death.  In a study of 32 patients presenting with unexplained atrioventricular block cardiac and whole body FDG PET were done. Eleven of them were diagnosed to have cardiac sarcoidosis. All these patients were subsequently diagnosed with extracardiac sarcoidosis as well. Three of them had presented with heart failure of which two also had recurrent ventricular tachycardia with ICD shocks [5].

Left ventricular ejection fraction, New York Heart Association functional class, left ventricular end diastolic diameter and sustained ventricular tachycardia have been shown to be important predictors of mortality in cardiac sarcoidosis in those treated with prednisone [6]. The presence of focal perfusion defects on rubidium-82 PET and FDG uptake could identify patients at higher risk of death or ventricular tachycardia in a study [7]. Presence of late gadolinium enhancement on MRI also predicted aborted sudden cardiac death and appropriate ICD discharge in another study [8].

Granulomas in the ventricular myocardium can cause ventricular tachycardia by abnormal automaticity or reentrant mechanism. Ventricular tachycardia is the most frequent arrhythmia in cardiac sarcoidosis which can occur in about a quarter of them. Atrial arrhythmias are less common and often secondary to atrial dilatation rather than atrial granulomas [9].

Though corticosteroids have been used for the treatment of cardiac sarcoidosis over the decades, due to the non-availability of randomized trial data, there is still debate on benefits vs harm and on the optimal dosage and duration of treatment. A whole lot of other agents like methotrexate, infliximab, azathioprine and cyclosporine have been used as steroid sparing agents in cardiac sarcoidosis, though concrete evidence for benefit is lacking. Successful use has been reported mainly in case reports and case series. Pacemakers and ICDs are important therapeutic options in relevant situations. Final option of heart lung transplantation may also be considered in cases with advanced heart and lung involvement [1].

References

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6. Yazaki Y, Isobe M, Hiroe M, Morimoto S, Hiramitsu S, Nakano T, Izumi T, Sekiguchi M; Central Japan Heart Study Group. 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. doi: 10.1016/s0002-9149(01)01978-6. PMID: 11703997.
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9. Doughan AR, Williams BR. Cardiac sarcoidosis. Heart. 2006 Feb;92(2):282-8. doi: 10.1136/hrt.2005.080481. PMID: 16415205; PMCID: PMC1860791.