Background:

Sarcoidosis is a systemic inflammatory granulomatous disease. Isolated manifestation of cardiac sarcoidosis(CS) is rare. The definitive diagnosis is challenging, and CS is often misdiagnosed due to different clinical presentations and overlaps with other cardiomyopathies.  

Here we present a case of a patient, assumed to have end-stage dilated cardiomyopathy(DCM) with recurrent ventricular tachycardias(VT) after viral myocarditis and who underwent heart transplantation (HTX). The CS was diagnosed only after the HTX during the examination of the explanted heart, 18 months after the first presentation.

Clinical case: 

A 36- year-old woman was referred to our clinic due to dyspnea and palpitations. ECG showed VT with heart rate of 250 bpm (Fig.1A), which was terminated by direct cardioversion. Echocardiography revealed mildly reduced left ventricular (LV) ejection fraction and LV dilation. Coronary artery disease was excluded. Manifestation happened shortly after the viral infection. MRI showed late gadolinium enhancement in the basal and midanteroseptal segments of LV, right ventricular apex and free wall and endomyocardial biopsy (EMB) from LV revealed Erythroparvovirus. Hence the diagnosis of dilatative cardiomyopathy (DCM) after myocarditis was made. After adjustment of pharmacological therapy, the LVEF was improved by up to 50%. Despite LV function improvement, during the next 1.5 years, the patient underwent in total 3 catheter ablations (CA) due to recurrent VTs different morphologies, Mitraclip implantation due to secondary severe mitral insufficiency and occluder implantation due to iatrogenic atrial septum defect. 

Due to HF deterioration and recurrent sustained hemodynamically relevant VTs, she underwent HTX. However, after the HTX, she died of sepsis caused by mycotic pneumonia. 

Interestingly, the EMB of the LV repeated for the pre-HTX screening showed unremarkable myocardium. Giant cells or granulomas were visible neither in conventional staining nor immunohistochemistry (IHC). Grossing of the heart explant revealed prominent paling and whitening of the outer myocardium, especially in the LV wall and the septum (Fig.1B). Microscopy showed a dense inflammatory infiltrate in the outer half of the myocardium (Fig.1C) with formation of multiple non-necrotizing epithelioid granulomas containing prominent giant cells (Fig.1D). Even though affecting a significant part of the myocardium, the lesion only reached the subendocardial regions in small areas (Fig. 1E), thus mainly remaining undiagnosable in EMB with a high chance for sampling error!

No extracardiac sarcoidosis manifestations were identified (especially no lymphadenopathy in thorax CT). 

Conclusion: CS has a large spectrum of symptoms and can mimic other cardiac diseases, causing HF and VTs. Usually, like in our case, different VT morphologies and poor ablation success are reported in CS.  Untreated CS can lead to end-stage HF; hence the early diagnosis is crucial. EMB can confirm the definitive diagnosis, although it has a high false negative rate due to sampling error. As seen in this case report, it happened because of patchy myocardial involvement and the almost absent subendocardial infiltration, making it impossible to reach with myocardial bioptome. The awareness of CS should be raised. In case of progressive deterioration of HF and recurrent ventricular arrhythmias in DCM with unclear aetiology, screening for CS as an alternative diagnosis could be considered