Diagnosis of immune checkpoint inhibitor-associated myocarditis: A systematic review

Myocarditis is a rare but severe adverse event associated with immune checkpoint inhibitors, its diagnosis depending on a high index of suspicion and appropriate investigations. Our objective was to systematically review the diagnostic approaches to myocarditis associated with immune checkpoint inhibitors.

The systematic review was conducted according to the PRISMA guidelines (PROSPERO Registration: CRD42018097247). We searched Medline and Embase for case reports, case series, and observational studies published in journal articles or presented as conference abstracts that describe patients who developed myocarditis after immune checkpoint inhibitor therapy.

After a review of 2326 citations, we included 88 cases (53 case reports/series published in journal articles and 35 cases in the observational study). Serum troponin was elevated in 98% of the case reports and 94% of participants in the observational study. ST changes including ST elevation were present in almost a third of case reports. Echocardiography revealed preserved left ventricular ejection fraction in 32% of case reports and 51% of cases in the observational study; however, preserved systolic function did not predict greater survival. Patients who suffered poorer prognosis tended to have major conduction defects or ventricular arrhythmias more frequently than patients who did not. Acute myocardial ischemia was ruled out in all cases (n = 31) when the diagnostic workup included coronary angiography.

Immune checkpoint inhibitor-associated myocarditis is characterized by elevation of cardiac troponin levels and non-specific electrocardiographic changes. Early coronary angiography may distinguish it from myocardial ischemia or myocardial infarction.