Blood biomarkers to detect functional impairment in adult patients with repaired tetralogy of Fallot.

Background: The relationship between plasma brain natriuretic peptide (NT-proBNP) and soluble suppression of tumorigenicity-2 (sST2) with structural adaptions and exercise capacity remains incompletely described in patients with repaired Tetralogy of Fallot (rTOF). Methods: Peripheral venous blood samples were drawn for 99 patients with repaired TOF, 59 patients with severe pulmonary regurgitation (PR) and 40 patients with no or mild PR. NT-proBNP was measured using enzyme-linked immunosorbent assays (Roche Diagnostics, Indianapolis, IN). Soluble ST2 levels were assessed on Aspect-plus ST2 quantitative rapid test. Results: The mean value of NT-proBNP was 160 ± 137 pg/ml, and sST2 was 29 ± 13, ng/ml in the entire population. 58 % had an elevated NT-proBNP, while sST2 was abnormal in 40 %. Mean NT-proBNP was significantly higher in patients with severe PR (169 ± 150 vs145 ± 118, pg/ml, p < 0.001), while similar sST2 levels were observed in both groups (29 ± 14 vs30 ± 12, ng/ml, p > 0.05). NT-proBNP and sST2 levels were higher in patients with transannular patch when compared to other RVOT intervention (174 ± 145 vs 107 ± 100, pg/ml, p < 0.001); (31 ± 13 vs 29 ± 15, ng/ml, p < 0.05). Both biomarkers were significantly associated with exercise capacity, but NT-proBNP (r = -0.60, p < 0.001) was stronger. The optimal cut-off of 90 pg/ml for NT-proBNP had a sensitivity of 74 % and specificity of 63 % for detection of impaired exercise capacity. Conclusions: Serum levels of sST2 and NT-proBNP are elevated in patients with repaired TOF, with higher values observed in those with severe PR, but also in patients undergoing transannular patch repair. Incorporating both markers in these patients increased the ability to detect impairment in exercise capacity.