Immune Checkpoint Inhibitor-Associated Myocarditis Mimicking Takotsubo Cardiomyopathy

Pembrolizumab-induced myocarditis is a rare but life-threatening immune-related adverse event.

A 72-year-old woman with stage IV EGFR exon 19 deletion-positive left lung adenocarcinoma received osimertinib as first-line therapy. After disease progression, she underwent pembrolizumab plus pemetrexed-carboplatin as second-line therapy, then docetaxel plus ramucirumab as third-line therapy. She presented with nausea and anorexia, and electrocardiograms revealed widespread ST-segment elevation. Coronary angiography revealed no significant stenosis; left ventriculography revealed an apical ballooning pattern. Although Takotsubo cardiomyopathy was suspected, endomyocardial biopsy confirmed pembrolizumab-induced myocarditis. High-dose corticosteroids improved her cardiac function; however, the underlying malignancy progressed.

Immune checkpoint inhibitor-associated myocarditis can mimic atypical Takotsubo cardiomyopathy, with persistent changes on electrocardiograms or elevated biomarkers, warranting endomyocardial biopsy for diagnosis and treatment with steroids.

In patients receiving immune checkpoint inhibitors, consider myocarditis in atypical Takotsubo presentations; biopsy and early steroids improve outcomes.