Abstract
Tyrosine kinase inhibitors (TKIs) can cause cardiotoxicity, and some suggest routine monitoring of cardiac function during TKI use. We describe two cases of TKI-induced heart failure (HF) that suggest the utility of monitoring with laboratory tests is questionable. One patient developed HF 5 days after starting pazopanib. The other developed HF while receiving 25 mg per day sunitinib, and had previously received a higher dose (50 mg per day) with no symptoms of cardiotoxicy. In addition, she later received 5 cycles of sunitinib (25 mg per day) without developing an abnormal left ventricular ejection fraction (LVEF) value by echocardiography or cardiac symptoms. Although the LVEF is commonly performed to monitor TKI cardiotoxicity, evidence for its predictive utility is limited. These cases raise questions regarding the practical utility of sequential measurement of LVEF in adults treated with TKIs. We suggest a simple daily activity such as stair climbing to monitor exercise tolerance.