IL-18 levels are associated with fibrosis, prolonged QTc, and mortality in patients with SCD. (A) Microarrays performed on PBMC-derived RNA in patients with SCD revealed a unique set of genes that were differentially regulated between patients who exhibited evidence of myocardial fibrosis on cardiac magnetic resonance imaging scans and those who did not. IL18 was 1 of the genes within this signature. (B) Gene expression profiling from PBMC-derived RNA of patients with SCD revealed longer QTc intervals associated with the patients with higher expression of IL18 (n = 8) compared with those with lower levels (n = 18) (*P = .047). Horizontal bar signifies mean of values. Error bars represent standard error. (C) Circulating plasma IL-18 levels are significantly correlated with QTc intervals in patients with SCD (n = 74; r = 0.53; P = .015). (D) Patients with SCD with increased circulating PBMC-derived IL18 expression had a significantly increased risk of death compared with those who had lower levels (P = .017).