Myocarditis: Uncommon but severe toxicity of immune checkpoint inhibitors

Traditional cancer therapies, such as treatment with anthracyclines and chest radiation, are known to induce cardiovascular complications. Currently, the increase of cancer therapies will involve new mechanisms such as cancer immunotherapies, also called immune checkpoint inhibitors (PD-1, PD-L1 and CTLA-4 inhibitors). These treatments have shown long-term remissions in subgroup of cancers, including melanomas, non-small-cell lung cancer, urothelial carcinoma, renal cell carcinoma, squamous cell carcinoma of the head and neck and colorectal cancer. Although these treatments will change the natural course of these cancers, they may sometimes induce cardiovascular complications, which has been reported as about 1 % in the literature. Currently, the physicians must keep in mind one uncommon but severe cardiac complication: auto-immune myocarditis. The clinical presentation may include various symptoms like chest pain, heart failure or rhythm disorders. In this situation, a baseline cardiologic check-up before starting cancer immunotherapy may be very helpful. Cardiac biomarkers (troponin and brain natriuretic peptide) and 12-lead resting electrocardiogram must be promptly performed when myocarditis is suspected. A cardiologist's opinion must be requested in emergency to discuss both a transthoracic echocardiography and the appropriate treatment (stopping immunotherapy, adding immunosuppressive treatment such as corticoids) and the monitoring in an intensive care unit. Cardiac MRI and endomyocardial biopsies may help to approach the final diagnosis. In this situation, other cancer therapies may be discussed.