Short‐ and Long‐Term Outcomes of Pericarditis, Myocarditis, and Myopericarditis in Patients With Malignancy on Immune Checkpoint Inhibitors

Background Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment but carry a risk of immune‐related adverse events, reported in 15% to 90% of the patients. ICI‐associated pericardial and myocardial disease has been increasingly recognized, yet data on outcomes remain limited. We aimed to use a large real‐world database to investigate the short‐ and long‐term outcomes of ICI‐associated pericarditis, myocarditis, and myopericarditis versus the non‐ICI cases. Methods We conducted a retrospective analysis using the TriNetX database to identify patients >18 years old on ICI and diagnosed with pericarditis, myocarditis, or myopericarditis within 1 year of initiation of therapy. The primary outcome assessed was all‐cause mortality, tamponade, constrictive pericarditis, and need for pericardiocentesis at 90‐day, 1‐year, and 5‐year follow‐up. Results A total of 3661, 226, and 46 patients were identified in matched cohorts of ICI‐induced pericarditis, myocarditis, and myopericarditis, respectively. One‐ and 5‐year mortality was greater for pericarditis (44.3% versus 37.3%; 54.3% versus 46.9%), myocarditis (38.9% versus 20.8%; 47.8% versus 34.3%), and myopericarditis (56.5% versus 28.3%; 63.0% versus 28.3%; all P ≤0.002). A multivariable Cox model showed increased ICI‐related mortality for pericarditis 1‐year hazard ratio [HR], 1.20 (95% CI, 1.12–1.29), 5‐year HR, 1.26 (95% CI, 1.18–1.35), myocarditis 90‐day HR, 1.82 (95% CI, 1.21–2.73), 1‐year HR, 2.04 (95% CI, 1.43–2.91), 5‐year HR, 1.64 (95% CI, 1.26–2.61), and myopericarditis 1‐year HR, 2.24 (95% CI, 1.15–4.37), and 5‐year HR, 2.78 (95% CI, 1.44–5.36), all with P