Cell Free DNA in Cardiac Sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of unknown cause that can affect any organ
in the body, including the heart. Sarcoidosis results from an immune reaction to an
environmental exposure to yet unknown antigen(s) in a genetically predisposed individual.
Autopsy studies have suggested that cardiac involvement with sarcoidosis occurs in up to 25%
of cases, although more than half of these cases are sub-clinical. Cardiac sarcoidosis (CS)
CS can lead to life-threatening heart failure, heart block, or rhythm disturbance and
accounts for 13-25% of all sarcoidosis deaths in the USA. Therefore, although respiratory
failure from lung sarcoidosis is the most common cause of sarcoidosis-related death in the
USA, sudden death from cardiac sarcoidosis is a major concern owing to its acute nature. CS
can present in a multitude of ways. It can be the initial manifestation of sarcoidosis in an
individual not known to have sarcoidosis (a cohort beyond the aims of this proposal),
patients can present with cardiac symptoms which can include palpitations, near-syncope or
syncopal episodes which require a complete workup for potential CS and patients can be
asymptomatic which is a sizable cohort considering the discrepancy between the expected
prevalence of CS (25-40%) and CS that is detected clinically (5%).

Granulomatous myocarditis can lead to ventricular dysfunction and ventricular arrhythmias
causing significant morbidity and mortality. Immunosuppressive therapy (IST) has been shown
to reverse active myocarditis and preserve left ventricular (LV) function and in some cases
improve LV function. In addition, IST can suppress arrhythmias that develop due to active
myocarditis and prevent the formation of scar. Cardiac MRI (cMRI) and cardiac PET scans are
currently used as complementary diagnostic tests for cardiac sarcoidosis, although with some
limitations. Cardiac MRI with gadolinium has a sensitivity of 76-100% and specificity of
78-92% for the diagnosis of cardiac sarcoidosis, but its use is limited in patients with
implantable cardiac devices. The presence of delayed enhancement on gadolinium-enhanced MRI
is suggestive of scar tissue formation. 18FDG PET uses radioactive glucose to detect areas of
active inflammation. The use of 18FDG PET as a marker of active granulomatous myocarditis
should be interpreted carefully as several studies have shown the limitations of such
protocols that force the myocardium to generate energy using free fatty acid metabolism
exclusively. In addition, studies have also shown that the presumed pathological patterns,
focal and focal on diffuse uptake, are also seen in healthy controls and patients with
ischemic congestive heart failure who have undergone 18-FDG-PET12 and that a blood glucose
level of >7.5mmol/L (>137mg/dl) at the time of the study results in absent or minimal
myocardial FDG activity.

The potential role of cardiac biomarkers, including brain natriuretic peptide (BNP), atrial
natriuretic peptide (ANP), and cardiac troponins, in detecting active myocarditis is limited
and studies have been disappointing. At present, there are no biomarkers to detect active
myocarditis and the use of advanced imaging modalities (FDG-PET) for assessing and monitoring
active myocarditis is not feasible or practical and is associate with high radiation
exposure. As such, a biomarker that is reflective of active myocarditis and that is cardiac
specific will assist physicians in assessing the presence of active myocarditis to guide
therapeutic decisions and to assess response to therapy which can limit further cardiac
damage.

Cell free DNA (cfDNA) are fragments of genomic DNA that are released into the circulation
from dying or damaged cells. It is a powerful diagnostic tool in cancer, transplant rejection
and fetal medicine especially when the genomic source differs from the host. A novel
technique that relies on tissue unique CpG methylation patterns can identify the tissue
source of cell free DNA in an individual reflecting potential tissue injury. A recent paper
utilized this technique to identify cardiac specific cfDNA in the bloodstream of patients
with acute myocardial injury and sepsis reflecting cardiomyocyte injury/death. We will be
conducting a pilot study to explore the utility of this diagnostic tool to identify
granulomatous myocarditis in patients with sarcoidosis.

1. Sarcoidosis patients without evidence of active myocarditis:

- Inclusion:

- Diagnosis of sarcoidosis based on the ATS/ERS criteria.

- Normal 12 lead ECG within the past one year.

- Non-smoker.

- No immunosuppressive therapy for at least one year.

- Exclusion:

- Known cardiac disease.

- Active smoker.

- On immunosuppressive therapy.

2. Sarcoidosis patients with evidence of active myocarditis:

- Inclusion:

- Diagnosis of sarcoidosis based on the ATS/ERS criteria.

- Evidence of active myocarditis based on recent cMRI or cFDG-PET.

- Non-smoker.

- Exclusion:

- Known cardiac disease other than sarcoidosis.

- Active smoker.

- On immunosuppressive therapy.

3. Acute ST elevation myocardial infarction (STEMI):

- Inclusion:

- Diagnosis STEMI based on 1mm ST elevation in 2 or more contiguous leads.

- Symptom onset within 12 hours.

- Undergoing cardiac intervention for acute coronary syndrome.

- Able to consent for blood draw.

- Exclusion:

- Active smoker.

- Hemodynamically unstable.

4. Healthy controls:

- Inclusion:

- No known cardiac disease.

- No known cardiovascular risk factors: hypertension, diabetes.

- Non-smoker.