PMC6529611_01
ECG baseline before starting nivolumab treatment: sinus rhythm at 60 bpm with isolated extrasystoles (A). ECG at myocarditis clinical onset: atrial fibrillation and left bundle branch block (B).
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Initial work-up revealed previously unknown atrial fibrillation and left bundle branch block in the electrocardiogram (ECG; Figure 1).
H&E section of myocardial tissue with necrotic focus containing dense lymphocytic infiltrates (A); immunohistochemistry of lymphoid component disclosing PD-1 cells (B), CD8 (C), and CD4 lymphocytes (D). 100x magnification.
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The ratio of CD8/CD4 cells was 80%/20%, and 40% of all lymphocytes were PD-1 positive (Figure 2). CD20 was negative. There were some macrophage CD68+ cells associated to necrotic myocardial muscle.