Comparison of prognosis in isolated versus systemic manifestations of cardiac sarcoidosis

Background: Isolated cardiac sarcoidosis (iCS) is a poorly understood and under-recognised entity. Previous research has postulated that those with iCS have worsened outcomes compared to those with other manifestations of the disease, however, there have been studies which both support and refute this hypothesis. Purpose of review: This review will summarise the literature which focuses on differences in the epidemiology, imaging findings and patient outcome of those with isolated cardiac sarcoidosis (iCS) versus 'systemic' cardiac sarcoidosis (sCS) which is not isolated to the heart. Summary: Variations in study design make accurate comparison between current papers challenging, and that the factors which indicate poor prognosis in patients with iCS is not yet fully understood. Current literature suggests those with iCS are more likely to be male, have higher numbers of abnormal uptake patterns on cardiac imaging, and may have poorer prognosis than sCS patients. Multi-centre, prospective studies analysing isolated cardiac sarcoidosis across geographical regions are needed to improve our understanding of this phenomenon and ultimately improve patient outcome.