{Reference Type}: Case Reports {Title}: Into the Unknown: A Case of New-Onset Cardiomyopathy in a Patient Treated With Recently Approved Tyrosine Kinase Inhibitor, Pralsetinib. {Author}: Papaila A;Jacobson AT; {Journal}: Cureus {Volume}: 13 {Issue}: 6 {Year}: Jun 2021 暂无{DOI}: 10.7759/cureus.15441 {Abstract}: With the rapid development and adoption of novel anti-cancer therapeutics, physicians commonly encounter cancer patients on regimens with recently approved drugs for which information about rare or long-term side effects may not be available. In this case, we present a young woman with cholangiocarcinoma who was treated with the rearranged during transfection (RET)-selective tyrosine kinase inhibitor (TKI), pralsetinib, and presented to the hospital with shortness of breath. We review her diagnosis of new-onset systolic dysfunction as a possible sequela of her TKI therapy to encourage ongoing efforts to enhance provider familiarity with the side effects of this important and increasingly prescribed drug class.