Preoperative serum LOXL2 levels are elevated in patients with pulmonary hypertension undergoing mitral valve surgery in a prospective observational cohort study.

Objectives: Lysyl oxidase like-2 (LOXL2) is associated with vascular remodeling associated in pulmonary hypertension (PH). This study evaluates the potential of serum LOXL2 levels as a clinical biomarker. Methods: We enrolled 158 patients undergoing mitral valve surgery . Using echocardiographic right ventricular systolic pressures (RVSPs), patients were stratified into those with and without PH pre-operative, post-operative, and post-discharge. Healthy volunteers served as a non51 surgical control. Serum LOXL2 concentrations pre-incision were compared to RVSPs using simple-regression and their relationship to PH using One-Way ANOVA with Tukey-posttest. Results: Serum LOXL2 concentrations were significantly higher in patients with PH compared to patients without PH (2,718 ±5187pg/ml vs. 640 ±1367 g/ml; P=0.0009) and compared to healthy volunteers (283 ±615pg/ml; P=0.04). There was a positive correlation between RVSPs and serum LOXL2 concentrations (p=0.02, r²=0.08). Serum LOXL2 levels positively correlated with intraoperative indices of pulmonary compliance, suggesting that PH in this cohort may primarily represent post-capillary PH. Patients with PH post procedure (and before discharge) had greater pre-procedure serum LOXL2 levels compared to patients without PH (4348 ±8498pg/ml vs. 1281 ±2329pg/ml, P=0.006); as did patients assessed after discharge (1359 ±2693pg/ml vs. 4195 ±6568pg/ml, P=0.009). Patients with persistent PH or new PH, had elevated pre-surgical LOXL2 levels compared to those without PH at both time points (4301 ±7717pg/ml vs. 556.6 ±835.8pg/ml, P= 0.02; 2902 ±5255pg/ml vs. 556.6 ±835.8pg/ml, P=0.03). Conclusions: Serum LOXL2 is elevated in patients with PH. LOXL2 is a potential PH biomarker in patients undergoing mitral valve surgery. This could have implications for follow-up care.