Case report: Electrocardiographic changes in pembrolizumab-induced fatal myocarditis

Figures

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  Figure 1. Chest computed tomography on admission. (A) Lung window shows a mass shadow in the lower lobe of the left lung. (B) Mediastinal window shows pericardial effusion.

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  Figure 2. Changes in electrocardiographic waveforms during hospitalization. The admission electrocardiogram showed (A) sinus tachycardia and low-voltage QRS complexes. (B) Negative T waves appeared on electrocardiogram 27 days after admission, and (C) monomorphic VT appeared 5 days later. Eight days after the start of methylprednisolone administration, (D) negative T waves remained but ST-segment elevation was no longer present. Pre-death electrocardiogram showed (E) R-on-T phenomenon triggered polymorphic VT. QT/QTc intervals: (A) 313/443 ms, (B) 395/507 ms, (C) 433/572 ms, (D) 408/482 ms, (E) 400/408 ms.

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  Figure 3. Cardiac biomarkers and electrolytes in blood tests after admission. CK and CK-MB decreased initially after methylprednisolone administration, and troponin T and NT-proBNP decreased later. Electrolytes values at the first occurrence of VT were K 4.1 mEq/L, Ca 9.1 mg/dL, Mg 1.8 mg/dL, and at the second occurrence of VT were K 4.7 mEq/L, Ca 8.9 mg/dL, Mg 2.0 mg/dL. Drugs that induce VT are not used.

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  Figure 4. Histological findings of endocardial biopsy. Histological findings of the myocardium showed (A) an infiltrate of inflammatory cells predominantly composed of lymphocytes by hematoxylin-eosin (HE) staining and (B) granulation fibrosis of the stroma by Masson’s trichrome (MT) staining. Immunostaining of the tissue showed (C) CD3-positive T cells infiltrated more than CD20-positive B cells. CD8-positive T lymphocytes infiltrated more than CD4-positive T lymphocytes. Infiltration of CD68-positive macrophages and CD138-positive plasma cells was also observed. (HE ×200, MT ×200 and CD3/CD4/CD8/CD20/CD68/CD138 immunostaining ×200).