Abstract 11037: Inappropriate Sinus Tachycardia and 18 FDG PET Scan

Abstract

Introduction: Inappropriate sinus tachycardia is a clinical syndrome characterized by an elevated heart rate at baseline with associated symptoms including palpitations. This entity can be quite disabling with no identifiable etiology in most cases. However, secondary causes need to be evaluated. This case highlights the utility of 18 F-Fluorodeoxyglucose PET in identifying myocarditis in a patient with systemic lupus erythematosus and in therapy changing management. Case: A 30-year-old female presented to the cardiology clinic with symptoms of palpitations for the past year with associated dizziness and fatigue, impairing her quality of life. Past medical history includes SLE, maintained on Hydroxychloroquine, and antiphospholipid antibody syndrome on warfarin. A resting EKG showed sinus tachycardia. Medical workup for sinus tachycardia was unremarkable. The patient had a normal echocardiogram. A 24-hour Holter monitor showed occasional PACs, a maximum HR of 167 with an average HR of 102 bpm, with symptoms of lightheadedness and palpitations correlating with sinus tachycardia (rates of 106 to 134 bpm). A treadmill exercise test was negative for ischemia with a peak HR of 196 bpm. Given suspicion for autoimmune myocarditis, an FDG PET using F18 was ordered showing abnormal di!use FDG myocardial uptake consistent with inflammation. The patient was started initially on metoprolol tartrate. She developed side e!ects, so she was switched to ivabradine and diltiazem. These findings were also communicated to her rheumatologist with a decision to aggressively treat her lupus disease. Methotrexate and a prednisone course were added. After 2 months, the patient reported improvement to near resolution of her symptoms. Conclusion: In this case, we aim to introduce the importance of cardiac PET nuclear imaging in addressing the relationship between inappropriate sinus tachycardia and autoimmune disease.