Red cell distribution width in adults with congenital heart disease: A worldwide available and low-cost predictor of cardiovascular events.

BACKGROUND Red cell distribution width (RDW) is a standard component of the automated blood count, and is of prognostic value in heart failure and coronary heart disease. We investigated the association between RDW and cardiovascular events in patients with adult congenital heart disease (ACHD). METHODS AND RESULTS In this prospective cohort study, 602 consecutive patients with ACHD who routinely visited the outpatient clinic were enrolled between 2011 and 2013. RDW was measured in fresh venous blood samples at inclusion in 592 patients (median age 33 [IQR 25-41] years, 58% male, 90% NYHA I) and at four annual follow-up visits. During 4.3 [IQR 3.8-4.7] years of follow-up, the primary endpoint (death, heart failure, hospitalization, arrhythmia, thromboembolic events, cardiac intervention) occurred in 196 patients (33%). Median RDW was 13.4 (12.8-14.1)% versus 12.9 (12.5-13.4)% in patients with and without the primary endpoint (P < 0.001). RDW was significantly associated with the endpoint when adjusted for age, sex, clinical risk factors, CRP, and NT-proBNP (HR 1.20; 95% CI 1.06-1.35; P = 0.003). The C-index of the model including RDW was slightly, but significantly (P = 0.005) higher than the model without (0.74, 95% CI 0.70-0.78 versus 0.73, 95% CI 0.69-0.78). Analysis of repeated RDW measurements (n = 2449) did not show an increase in RDW prior to the occurrence of the endpoint. CONCLUSIONS RDW is associated with cardiovascular events in patients with ACHD, independently of age, sex, clinical risk factors, CRP, and NT-proBNP. This readily available biomarker could therefore be considered as an additive biomarker for risk stratification in these patients.