Contemporary Diagnostics of Cardiac Sarcoidosis: The Importance of Multimodality Imaging

Abstract

Sarcoidosis is an inflammatory condition that can affect multiple organ systems and is characterized by the formation of non-caseating granulomas in various organs, including the heart. Due to suboptimal diagnostic rates, the true prevalence and incidence of cardiac sarcoidosis (CS) remain to be determined. In patients with suspected CS, an initial examination should include 12-lead ECG or ambulatory ECG monitoring, and echocardiography with the estimation of LV, RV function, and strain rate. In patients with confirmed extracardiac sarcoidosis and with high clinical suspicion for CS, sophisticated imaging modalities, including cardiac MRI and PET, are indicated. Typical inflammation patterns and myocardial scarring should pose a high suspicion for CS. In patients without diagnosed extracardiac sarcoidosis and high clinical suspicion, although with low diagnostic probability, an endomyocardial biopsy should be considered to establish the diagnosis of definite isolated cardiac sarcoidosis. Timely diagnosis enables the initiation of therapy and close monitoring of adverse cardiac events that can be life-threatening, including sudden cardiac death, ventricular tachycardia, high-degree AV block, and heart failure. Implementing biomarkers in correlation to cardiac imaging can determine the disease's severity and progression but can also be helpful in following the treatment response. The formation of larger global registries can be helpful in the identification of independent predictors of adverse clinical events and the development of specific diagnostic algorithms to reduce the overall risk of this serious condition.

Keywords: cardiac magnetic resonance; cardiac sarcoidosis; cardiovascular imaging; echocardiography; electrocardiography; positron emission tomography.

Figure 1

Myocardial strain in a patient with cardiac sarcoidosis and reduced ejection fraction: Reduced values of GLS predominantly in basal segments of the septum (marked with arrows).

Figure 2

Endomyocardial biopsy in a patient with cardiac sarcoidosis reveals a non-necrotizing granulomatous inflammation (marked with arrow) with patchy interstitial fibrosis on hematoxylin and eosin staining.

Figure 3

Cardiac magnetic resonance in a patient with cardiac sarcoidosis: (a) LGE MAG study, short axis: LGE in septum and inferior segments (marked with arrows); (b) LGE PSIR study, short axis: LGE changes in left and right ventricle, predominantly in septal segments (marked with arrows) (Avanto MRI, Siemens Healthcare GmbH, Erlangen, Germany, 1.5 T, CMR Lab University Clinical Hospital Center Bezanijska kosa, Belgrade, Serbia).

Figure 4

Myocardial tissue mapping in a patient with cardiac sarcoidosis and high degree AV block: native T1 mapping revealing the areas of shortened native T1 time indicating myocardial fibrosis predominantly in the septum (marked with arrows) (Avanto MRI, Siemens Healthcare GmbH, Erlangen, Germany, 1.5 T, CMR Lab University Clinical Hospital Center Bezanijska kosa, Belgrade, Serbia).

Figure 5

Cardiac PET in a patient with cardiac sarcoidosis: ¹⁸F-FDG uptake in most of left ventricle, consistent with active inflammation; No significant uptake in apex or mid-inferolateral segment, compatible with possible fibrosis ((a)—apex, (b)—mid-ventricle, (c)—basal).

Figure 6

Implementation of multimodality imaging into diagnostic algorithm for the diagnosis of cardiac sarcoidosis.