Atrial arrhythmias with mediastinal lymphadenopathy presentation of isolated atrial myocarditis

We present a case series of patients with granulomatous myocarditis presenting as atrial arrhythmias accompanied by lymphadenopathy.

Atrial myocarditis (AM) may be the cause of atrial fibrillation (AF) in patients without risk factors.

Patients with atrial fibrillation without risk factors underwent 18F-Fluorodeoxyglucose positron emission tomography (18F-FDG-PET). We performed biopsy of lymph nodes or myocardium in patients with atrial uptake of 18F-FDG-PET.

AM was observed in 15 patients. The median age of the patients was 42 years and left ventricular ejection fraction (LVEF) at presentation was 45%. All patients had AF, atrial flutter was noted in 4 patients (26.7%) and 2 patients (13.3%) had atrioventricular nodal reentrant tachycardia (AVNRT). 18F-FDG-PET uptake was noted in the atria in all patients and in the ventricles in 3 patients (20%). Cardiac sarcoidosis was the diagnosis in 12 patients (80%) while 3 patients (20%) had tuberculosis. The median CHA2DS2 VASc score was 1. Four patients (26.7%) presented with ischemic stroke. All patients were treated with disease-specific therapy in addition to antiarrhythmic medications. Over a median follow up of 26 months, a significant improvement in clinical status commensurate with a decline in atrial uptake was noted. A non-significant improvement in LVEF to 56% with disease-specific therapy was observed. (p = 0.09).

Atrial fibrillation with granulomatous lymphadenopathy may be a presenting feature of AM. The risk of stroke is high in these individuals. AM should be suspected in young individuals presenting with atrial fibrillation and stroke without conventional risk factors.