Background: Angiotensin-I-converting enzyme (ACE), soluble Interleukin-2-receptor (sIL2R) and Neopterin are laboratory markers for pulmonary sarcoidosis. The importance of these biomarkers for cardiac pathologies in patients with myocardial biopsy proven cardiac sarcoidosis (CS) is not known.

Methods: We studied ACE, sIL2R and Neopterin in 20 patients with CS that was proven by endomyocardial biopsy (EMB). The mean follow-up (FU) was 21 months. Left ventricular ejection fraction [LVEF], the presence of arrhythmias and the clinical course of the disease were analyzed in relation to the serum concentrations of the three laboratory parameters over time.

Results: The mean values of the total cohort of ACE, sIL2R and Neopterin at time of diagnosis were within normal ranges (38.4 +/- 15.7 U/l [reference range 20-70], 9.7 +/- 4.2 nmol/l [reference range <10] and 496.5 +/- 723.4 U/ml [reference range 158 – 623], respectively. No patient, two patients and four patients showed pathological values for ACE, sIL2R and Neopterin at the time of diagnosis. No patient developed pathological ACE values during FU. The two patients with elevated sIL2R at baseline showed persistent elevated values, whereas the four patients with elevated Neopterin values showed fluctuating values during FU. Of note, nine patients with initially normal Neopterin values showed pathological values during FU. There was no significant association of presence of FDG-uptake in PET-CT, presence of LGE in CMR, ventricular arrhythmias or higher degree AV block with serum concentrations of ACE, sIL2R or Neopterin. During follow-up, deterioration of the LVEF occurred in eight patients without a significant association to the change of ACE, sIL2R and Neopterin values (p=0.23, p=0.05 and p=0.89, respectively). Furthermore, there was no association between the occurrence of arrhythmias and absolute or relative laboratory values over time.

Conclusion: Most of the patients with EMB proven CS show normal values of ACE, sIL2R and Neopterin. Cardiac findings at time of diagnosis and during FU do not associate with absolute values or change over time of ACE, sIL2R and Neopterin.