Interleukin-1 Receptor-Related Protein ST2 and Mitral Valve Repair Outcome in Patients with Chronic Degenerative Mitral Regurgitation

Background: ST2 is a member of the interleukin-1 receptor family that is markedly upregulated in cultured cardiomyocytes subjected to mechanical strain. Serum soluble ST2 (sST2) levels can be detected in patients with acute myocardial infarction and severe chronic heart failure. This study sought to assess for the first time the activation of the ST2 pathway in patients with severe chronic degenerative mitral regurgitation. Materials and methods: Serum sST2 levels were measured in 20 patients scheduled for mitral valve (MV) repair at baseline, at the end of the intervention, on postoperative day 1, at hospital discharge, and after 6 months. Patients also underwent measurement of N-terminal pro-brain natriuretic peptide and echocardiographic evaluation at each time point. Results: At baseline, sST2 was detected in 10 (50%) patients (mean value, 60 ± 74 pg/mL; range, 0-234 pg/mL; median, 8 pg/mL). MV repair was performed successfully in all patients. Cardiac surgery with cardiopulmonary bypass was associated with a rapid and transient increase in sST2 levels. Patients with baseline higher versus lower sST2 levels (≥ 8 vs. < 8 pg/mL) had significantly higher levels of sST2 on postoperative day 1 (1,050 ± 593 vs. 440 ± 312 pg/mL; p = 0.009). At follow-up, patients with preoperative sST2 ≥ 8 pg/mL had significantly higher ejection fraction (EF) (64.7 ± 5.8 vs. 57.6 ± 5.9; p = 0.03) and lower left ventricular end-diastolic diameter (LVEDD) (50.6 ± 5.8 vs. 56 ± 4.2; p = 0.03) compared with patients with preoperative sST2 < 8 pg/mL. Conclusion: Preoperative ST2 activation, evidenced by the presence of serum sST2 levels, is present in half of the patients with chronic degenerative mitral regurgitation and is associated with higher levels of EF and lower levels of LVEDD after MV repair.