Cardiology (Heart)

Immune checkpoint inhibitors (ICIs) represent one of the most exciting therapeutic advancements in the field of oncology. While myocarditis is one of the rarest side effects of immune checkpoint inhibitor (ICI) therapies with an incidence of 1%, it ranks as one of the deadliest with a mortality rate approaching 25–50% [1]. The nuances involved in diagnosing ICI-associated myocarditis and a wide range of symptoms characterizing the clinical presentation create a challenge in identifying with great specificity the disease in clinical trials, in clinical case series, and, ultimately, in patients [2]. The keys to diagnosis and treatment of ICI-associated myocarditis lie with a circumspect understanding of the various cardiac biomarkers, noninvasive imaging modalities, and invasive methods that are combined in conjunction with the patient’s clinical presentation to establish the diagnosis and treatment plan. While ICI-associated myocarditis is a clinically distinct entity, the emerging diagnosis and treatment strategies for this disease are founded on the diagnostic and treatment principles established for cardiotoxic chemotherapy agents, viral myocarditis, and cardiac allograft rejection. However, ICI-associated myocarditis remains unique in that there remains much work in not only seeking a uniform definition for the disease process but also in discovering increasingly specific biomarkers and novel imaging techniques to further aid in diagnosis. Furthermore, while high-dose steroids are acknowledged as a mainstay treatment for the disease, the discovery of second-line agents that may successfully control disease progression is still underway, in addition to identifying the patient characteristics for those at highest risk of failing frontline therapies.