Relationship of Red Cell Distribution Width to Adverse Outcomes in Adults With Congenital Heart Disease (from the Boston Adult Congenital Heart Biobank)

Red cell distribution width (RDW), a measure of variability in red cell size, predicts adverse outcomes in acquired causes of heart failure. We examined the relation of RDW and outcomes in adults with congenital heart disease. We performed a prospective cohort study on 696 ambulatory patients ≥18years old enrolled in the Boston Adult Congenital Heart Disease Biobank between 2012 and 2016 (mean age 38.7 ± 13.5 years; 49.9% women). The combined outcome was all-cause mortality or nonelective cardiovascular hospitalization. Most patients had moderately or severely complex congenital heart disease (42.5% and 38.5%, respectively). Mean RDW was 14.0 ± 1.3%. RDW15% was present in 81 patients (11.6%). After median 767days of follow-up, 115 patients sustained the primary combined outcome, including 31 who died. Higher RDW predicted both the combined outcome (hazard ratio [HR] for RDW15% = 4.5, 95% confidence interval [CI] 3.0 to 6.6; HR per + 1SD RDW = 1.8, 95% CI 1.6 to 2.0, both p0.0001) and death alone (HR for RDW15% = 7.1, 95% CI 3.5 to 14.4; HR per + 1SD RDW = 1.8, 95% CI 1.6 to 2.0, both p0.0001). RDW remained an independent predictor of the combined outcome after adjusting for age, cyanosis, congenital heart disease complexity, ventricular systolic function, New York Heart Association functional class, hemoglobin concentration, mean corpuscular volume, high-sensitivity C-reactive protein and estimated glomerular filtration rate (HR per + 1SD RDW = 1.5, 95% CI 1.2 to 1.9, p0.0001). RDW also remained an independent predictor of mortality alone after adjustment for age plus each variable individually. In conclusion, elevated RDW is an independent predictor of all-cause mortality or nonelective cardiovascular hospitalization in adults with congenital heart disease. This simple clinical biomarker identifies increased risk for adverse events even among patients with preserved functional status.