PO-04-050 ROLE OF FDG-PET CT IN GUIDING THERAPY FOR RELAPSING AND REMITTING MYOCARDITIS

Abstract

Fluorodeoxyglucose (FDG)-positron emission tomography (PET) scan is considered as a goal standard test for the diagnosis of myocarditis. Low intensity FDG uptake of the lateral wall without perfusion abnormalities is considered to be a variant of normal. It is imperative to correlate myocardial and pericardial abnormality revealed by myocardial FDG uptake with the signs and symptoms of myocardial disease, as it tends to be overlooked. However, recognition of possible underlying disease will support further patient management to avoid complications due to the disease. While the utility of FDG PET in the diagnosis of myocarditis and initiation of therapy is well documented, there is no consensus in the preferred strategy for monitoring the response to therapy. To present a case highlighting the utilization of FDG PET in guiding the therapy for relapsing/remitting myocarditis. N/A A 55yo male presented with new onset HF with LVEF of 15-20% at the time of index presentation. He underwent cardiac catheterization which showed non-obstructive CAD. He was diagnosed with NICM and was discharged home on GDMT with a wearable external defibrillator. His outpatient work-up with FDG PET imaging showed normal perfusion with FDG uptake involving the proximal, mid inferolateral, and lateral region with a SUV-max of 3.4. Biopsy was determined to be too high-risk and was therefore not pursued. He was diagnosed with chronic idiopathic myocarditis with possible isolated cardiac sarcoidosis and started on methotrexate (MTX). Prednisone was considered but decided against due to comorbid diabetes. His follow up FDG PET in 6 months reported an increase in the SUV max to 4.2 and involvement of lateral base in addition to the mid-inferolateral region [Figure 1(a),(b)]. Due to lack of improvement, the patient was switched from MTX to mycophenolate. Repeat 6 month follow up FDG PET showed resolution of myocarditis with SUV-max of 2.6 [Figure 1(c),(d)] and patient was taken off immunosuppressive therapy. Six-month follow-up FDG PET was unchanged and was thus reassuring. One year later, the patient relapsed with focal FDG uptake of entire lateral and mid and basal inferolateral walls with an SUV max of 11.2 on imaging [Figure 1(e),(f)]. The patient was consequently restarted on mycophenolate therapy. This case highlights the relapsing and remitting clinical course of a patient with FDG-PET uptake in myocardium which was treated with immunosuppressive therapy with serial FDG-PET guidance.