Atrial Giant Cell Myocarditis as a Cause of Heart Failure

We present a patient with acute heart failure and new onset atrial fibrillation secondary to giant cell myocarditis with lone atrial involvement. The diagnosis was managed with cardiac magnetic resonance and confirmed by interventionally guided biopsy. In the future, diagnosis could be managed noninvasively for this rare entity as the gold standard. (Level of Difficulty: Advanced.)
Graphical abstract