Evaluation of Diagnostic Criteria in Cardiac Sarcoidosis - an Observational Study

Sarcoidosis is an inflammatory condition rarely affecting the heart, exhibiting fluctuating disease activity and eventually leading to ventricular fibrosis. Clinical presentation ranges from no symptoms at all to life-threatening arrhythmias, heart failure and death in severe cases. The heart lesions show patchy distribution and can mimic virtually any other type of cardiomyopathy, which poses significant challenges for the accurate and eary diagnosis.

At present, there are four diagnostic tools and recomendations for diagnosis of cardiac sarcoidosis (CS) that utilize clinical, ECG, laboratory, imaging and biopsy criteria. Recently, it was demonstrated that there is a significant diagreement between these four diagnostic tools. On the other hand, earlier identification of patients with active inflammatory process is necessary, as they are those who will most likely benefit from immunosuppressive therapy.

The aim of this observational study is to evaluate the prognostic significance of the current clinical, ECG, laboratory, imaging and biopsy criteria for diagnosing cardiac sarcoidosis. Patients with suspected cardiac sarcoidosis based on clinical symptoms will recieve elaborate diagnostic work-up consisting of: evaluation of symptoms, family history, occupational hazards, ECG, chest X-ray, laboratory markers for sarcoidosis, positron emission tomography (PET), cardiac magnetic resonance (CMR) as well as endomyocardial biopsy.

In accordance to the recomendations of the current guidelines, the patients will be devided into 3 groups: 1) patients with proven CS; 2) patients with probable CS; and 3) unlikely CS that will serve as a reference group. The patients in first two groups will be treated with immunosuppressive therapy, mainly glucocorticoids (GC). The follow-up at 3, 6, 12 and 24 months will consist of evaluation of the symptoms using dedicated King's Sarcoidosis Questionaire (KSQ), fatigue assessment scale (FAS), Holter-ECG, pacemaker interrogation, laboratory findings, imaging with PET and CMR.

Clinical outcomes will be defined as: 1) improvement of symptoms (FAS score, heart failure class, AV block, ventricular arrhythmias, and KSQ score) and 2) improvement of imaging parameters ( left ventricular ejection fraction, PET activity, myocardial edema, scar in CMR). The outcomes between the groups will be compared using group 3 as reference. Furthermore, patients with improvement with GC (successful therapy) will be compared with those without improvement (unsuccessful therapy) and the predictive value of each diagnostic criterion will be evaluated. Finally, the odds ratios (OR) for each parameter will be used to calculate a diagnostic and predictive score which will be used prospectively to evaluate patients with suspected CS and to guide the therapy.