Cardiac Sarcoidosis Flashcards
Which organs are commonly affected in sarcoidosis?
Lungs, heart, liver, spleen, skin, eyes, parotid
What epidemiological factors are associated with sarcoidosis?
Age (most disease occurs in 25-60 yo)
Race (more common in northern Europeans and African Americans)
Sex (Female)
What is the approach to the diagnosis of cardiac sarcoidosis?
The gold standard is a histological diagnosis with evidence of non-caseating granulomas without an alternative explanation.
A clinical diagnosis is based on determining the probability of cardiac sarcoidosis:
Ideally, this would include a histological diagnosis of extra-cardiac sarcoidosis in addition to specific cardiac-related abnormalities. Some algorithms suggest undertaking a HRCT to assess for changes suggestive of pulmonary sarcoidosis if the patient is not known to have extra-cardiac sarcoidosis.
Cardiac specific abnormalities include:
- Unexplained LVEF < 40%, unexplained ventricular tachycardia, unexplained Mobitz II or CHB in a patient < 60 years.
- Tissue characterization suggestive of cardiac sarcoidosis: LGE on CMR, patchy uptake on dedicated cardiac FDG-PET, positive gallium uptake (in patterns consistent with CS)
- Steroid +/- immunosuppressant-responsive cardiomyopathy or heart block
AND other causes for the cardiac abnormalities have been reasonably excluded
What pattern of LGE is characteristically observed in cardiac sarcoidosis?
What is the role of T2-STIR imaging?
Patchy, multifocal involvement with sparing of the endocardial border (i.e mid-myocardium and epicardium are involved). LGE is most commonly seen in the basal segments, particularly the septum and lateral wall.
T2-STIR can detect oedema which may indicate active inflammation.
What is the yield of endomyocardial biopsy with and without image-guided assistance?
< 25% or up to 50% for image-guided biopsy. Image-guided biopsy includes EAM to target low voltage areas (the biopsy forceps can be positioned near a mapping catheter in a low voltage area via fluoroscopy), PET or CMR-guided biopsy
How should patients with extra-cardiac sarcoidosis be screened for cardiac involvement and what is the role of CMR / PET in these patients?
Screening for symptoms (unexplained (pre-)syncope, palpitations) and with a 12 lead ECG are Class I recommendations.
Screening for LV dysfunction with an echocardiogram is a class IIa recommendation
CMR and/or FDG-PET should not be performed unless there are abnormalities in any of the above.
What are the 3 main indications (Class IIa recommendations) for ICD insertion irrespective of LVEF in patients with cardiac sarcoidosis?
- Indication for PPM implantation
- Unexplained syncope or near syncope felt to be arrhythmic in aetiology
- Inducible sustained VT
Can consider ICD for LVEF 36-49% after period of GDMT and immunosuppression (IIb)
What is the mechanism of ventricular arrhythmias in patients with cardiac sarcoidosis and how should these be managed?
VAs usually arise due to macro-reentry around areas of granulomatous scar. Active inflammation may promote ventricular ectopy or slow conduction in diseased tissue within granulomatous scar.
FDG-PET is undertaken to assess for active inflammation and management involves anti-arrhythmic drugs PLUS immunosuppression if there is active inflammation.
Catheter ablation can be undertaken if arrhythmia persists despite the above measures
What is the approach to steroid dosing for treating active inflammation in cardiac sarcoidosis?
Generally start at a dose of 0.5 mg/kg/day for 3 months and reassess for ongoing inflammation. If there is no ongoing inflammation, slowly wean the steroids over the next 9 months.
Methotrexate is indicated for ongoing inflammation despite adequate steroid dosing or if a patient relapses following a steroid wean / steroid cessation.
Another approach is early and aggressive treatment with parenteral steroids; if there is a good clinical response, early introduction of a steroid-sparing agent could be considered.
What is the data for the steroid-responsiveness of conduction disease, ventricular arrhythmias and LVEF in patients with active inflammation cardiac sarcoidosis?
Conduction disease can improve in ~50%
Impact on ventricular arrhythmias is unclear
Impact on LVEF unclear; however some data to suggest that patients with mild to moderate LV dysfunction can experienced improvement in LVEF. Patients with severe LV dysfunction may already have irreversible structural changes to explain reduced steroid responsiveness.
What is the mechanism of action of methotrexate + how should it be prescribed and monitored?
For cancer treatment, methotrexate competitively inhibits dihydrofolate reductase which is necessary for the conversion of dihydrofolate to tetrahydrofolate, necessary for DNA and RNA synthesis.
For rheumatological conditions, it seem to dampen the immune response including inhibition of T cell activation and down-regulation of B-cells.
Methotrexate is usually prescribed weekly with folic acid supplementation.
Side effects include mucosal injury with oral ulcers and GI symptoms, cytopaenias, liver enzyme derangement and rarely pulmonary fibrosis or renal failure. MTX is also teratogenic.
