Predictors of long-term survival in immune checkpoint inhibitor (ICI)-associated myocarditis.

Abstract

e24026 Background: ICI-associated myocarditis carries a high morbidity and mortality, with close to half of patients experiencing major adverse cardiac events (MACE). Risk factors previously associated with short-term MACE include troponin T (TnT), neutrophil/lymphocyte ratio (NLR), and absolute lymphocyte count (ALC). In this study, we aimed to analyze the predictors of long-term survival. Methods: This single-center retrospective study included 37 patients diagnosed with ICI-associated myocarditis at Massachusetts General Hospital between March 2016 and March 2022. We collected demographics, diagnostic results, and myocarditis treatments from the electronic medical record. Patients were grouped by survival time: short-term ( < 30 day), intermediate (30 to 360 day), or long-term ( > 360 days) survival. We used chi-square and Kruskal-Wallis tests for descriptive statistics. Cut-off points of continuous variables were determined by ROC curve. Predictors of survival were analyzed by logistic regression models. Results: The cohort consisted of 29 males and 8 females with a median age of 75 years (IQR 68-79), and median follow-up of 5.6 months (IQR 0.5-14.9). The median time from ICI start to myocarditis onset was 50 days (IQR 36-91). Ten, 14, and 13 patients were in the short-term, intermediate, and long-term survival groups, respectively. By univariate analysis, predictors of long-term survival included initial NT-proBNP ≤ 450, NLR ≤ 4.44, ALC ≥ 1122, normal EKG QTc interval (≤ 450 ms in male or ≤ 460 ms in female), and TnT decrement ≥ 42% by day 8 of immunosuppression (Table 1). All patients with long-term survival presented with a normal left ventricular ejection fraction (LVEF ≥ 55%), which made it uninterpretable using logistic regression models. Normal LVEF was significantly associated with long-term survival by using chi-square test (p = 0.002). While TnT elevation > 75x the upper limit of normal (ULN) was strongly associated with short-term survival (p = 0.001), it was not associated with long-term survival (p = 0.23). The use of second-line immunosuppression in addition to corticosteroids did not have a significant impact on long-term survival (p = 0.69). Conclusions: NLR, ALC, NT-proBNP, QTc interval, and a substantial decrease in TnT at day 8 after immunosuppression are all associated with long-term survival in ICI myocarditis. [Table: see text]