Increased Heart Rhythm in Response to High-dose Intravenous Methylprednisolone Pulse Therapy of Moderate-to-severe Graves' Orbitopathy

High doses of intravenous (iv.) glucocorticoids (GCs) are commonly used as a treatment for many autoimmune and inflammatory disorders. According to the European Group on Graves' Orbitopathy (EUGOGO) guidelines, intravenous methylprednisolone (IVMP) is an accepted first-line agent for active, moderate-to-severe and very severe Graves' orbitopathy (GO). This treatment is proven to be more efficient and safer than oral GCs. However, some patients may experience adverse cardiovascular effects during the administration of iv. GCs, which in rare cases may even be fatal. There are limited data, mostly obtained from case reports, reporting the occurrence of cardiac arrhythmias, acute myocardial infarction or heart failure. Increased heart rhythm (HR) has drawn attention of researchers as a possible adverse effect correlated with IVMP. During this study, investigators performed 72-hours of Holter ECG and ambulatory blood pressure monitoring (ABPM) to evaluate the impact of IVMP on patients with moderate-to-severe GO, concerning HR and blood pressure (BP) changes. In order to elucidate possible mechanism of observed changes, researchers investigated the level of potassium in serum and urine and catecholamines (epinephrine, norepinephrine) in serum. All patients were treated routinely according to EUGOGO recommendations with standard doses of methylprednisolone with standard recommended schedule. Inclusion criterion for the therapy was according to EUGOGO guidelines active, moderate-to-severe and active GO (12 pulses of IVMP 6x0.5g followed by 6x0.25g every week).