Atrial giant cell myocarditis after atrial fibrillation ablation.

Case summary

A 72-year-old woman underwent pulmonary vein isolation of paroxysmal atrial fibrillation (AF). Five months after the ablation she was admitted to our hospital for a cough and slight fever refractory to medical therapy. Cardiac positron emission tomography (PET) revealed a left atrial (LA) fluorodeoxyglucose (FDG) uptake consistent with myocarditis. A LA biopsy was consistent with atrial giant cell myocarditis (GCM). After treatment with corticosteroids, she returned to a normal life. Cardiac imaging including FDG-PET and an atrial wall biopsy may contribute to understanding the atrial pathology.

Case description

A 72-year-old woman without a previous history of cardiac disease underwent radiofrequency ablation of year-long paroxysmal AF consisting of a pulmonary vein isolation (PVI) without any LA substrate modification. Five months after the ablation she was admitted to our hospital for a cough and slight fever refractory to medical therapy. An ECG exhibited recurrent paroxysmal AF with a mean of 112 b.p.m. and no evidence of myocardial ischaemia. Chest computed tomography revealed mild pleural and pericardial effusions without any pulmonary emboli. For the first time, laboratory testing revealed an elevated C-reactive protein level (57 mg/L). Transoesophageal echocardiography revealed mild dilatation with an LA diameter of 38 mm despite there having been no dilatation of the LA just after the ablation (29 mm). Transoesophageal echocardiography revealed wall thickening limited to the LA. Cardiac magnetic resonance imaging showed there was wall thickening with marked oedema. Cardiac PET after a 24-h carbohydrate-free diet revealed an LA FDG uptake consistent with myocarditis (Figure ). An extensive infectious work up was negative. An LA biopsy under intracardiac echocardiography (ICE) guidance revealed granulomatous and lymphocytic inflammation of the myocardium, which was consistent with atrial GCM (Figure ). After treatment, starting with only prednisolone 40 mg per day to tapering to 15 mg, she returned to a normal life after 2 months of follow-up. Atrial fibrillation was the only detected arrhythmia during the course of the atrial GCM. Atrial fibrillation recovered to sinus rhythm during treatment under the administration of dabigatran and cibenzoline. Following that, no further AF recurred during 16 months of follow-up.

Cardiac positron emission tomography revealed a left atrial fluorodeoxyglucose uptake consistent with myocarditis.

Representative photomicrographs of the atrial myocardium. Myocardium with granulomatous and lymphocytic inflammation is present. Haematoxylin and Eosin. Bars, 100 μm.

This case exhibited a new variant of GCM with lone involvement of the LA and a preserved left ventricular function. The isolated atrial involvement was implicated as a cause of the AF in spite of an AF ablation., However, this ablation procedure might not have been associated with the development of atrial GCM, because the sudden onset of the disease was found more than at least 5 months after the ablation, and LA wall thickening could also be observed in the LA body and LA appendage (Supplementary material online, ).

Atrial cardiomyopathies generally may have long been overlooked. Atrial GCM may be considered as a cause of recurrent AF after an AF ablation. Cardiac imaging including FDG-PET and an atrial wall biopsy under guidance with ICE may contribute to understanding the atrial pathology.

Supplementary material

Supplementary material is available at European Heart Journal - Case Reports online.

Consent: The author/s confirm that written consent for submission and publication of this case report including image(s) and associated text has been obtained from the patient in line with COPE guidance.

Conflict of interest: none declared.

Click here for additional data file.