The inflammatory biomarker YKL-40 decreases stepwise after exercise stress test

Abstract

Background: Serum YKL-40 is an inflammatory biomarker associated with disease activity and mortality in diseases characterized by inflammation such as coronary artery disease (CAD). Exercise has a positive effect on CAD, possibly mediated by a decreased inflammatory activity. This study aimed to compare serial measurements of serum YKL-40 before and after exercise in patients with stable CAD versus controls.

Materials and methods: Eleven patients with stable CAD verified by coronary angiography (>70% stenosis) and 11 patients with a computer tomography angiography with no stenosis or calcification (calcium score=0) (controls) performed a standard clinical maximal exercise test. Serum YKL-40 was measured before exercise, immediately after exercise, and every hour for 6 h.

Results: Cardiovascular risk factors were more prevalent among the CAD patients compared with the controls. CAD patients had higher serum concentration of YKL-40 at baseline compared with controls, median (interquartile range) 94 (52-151) versus 57 (45-79) μg/l. Serum YKL-40 decreased stepwise after exercise, with a median decrease of 16 (13-39) μg/l for the CAD patients and 13 (10-22) μg/l for the controls from baseline to the lowest value. Thereafter, values increased again toward baseline level. Time after exercise was a significant factor for decrease in serum YKL-40 (P<0.0001), but no difference in YKL-40 decrease over time could be demonstrated between the groups (P=0.12).

Conclusion: Serum YKL-40 is elevated in patients with documented CAD compared with controls, and it decreases stepwise after exercise in both groups, indicating an anti-inflammatory effect of exercise independent of the presence of coronary atherosclerosis.

Keywords: biomarkers; coronary artery disease; exercise test; inflammation; serum YKL-40; stable angina pectoris.

Fig. 1

Concentrations of serum YKL-40 (μg/l). Serum YKL-40 was measured at baseline, immediately after exercise, and once every hour for 6 h in patients with documented CAD (gray) and controls (black). Data are presented as median (line), interquartile range (box), and minimum and maximum observations (whiskers).

Fig. 2

Individual changes in serum YKL-40 (μg/l) after exercise test. Serum YKL-40 was measured at baseline, immediately after exercise, and once every hour for 6 h after exercise. The lines represent each individual. (a) CAD patients; (b) controls. The horizontal dotted line represent 95th percentile (YKL-40 concentration) according to the mean age for each group . CAD, coronary artery disease.

Fig. 3

Mixed model for the interaction of time after exercise test and group (CAD patients vs. controls). y-axis: YKL-40 (LS-mean). x-axis: time after exercise test. CAD, coronary artery disease; LS, least square.