Association of Lp-PLA2 with digital reactive hyperemia, coronary flow reserve, carotid atherosclerosis and arterial stiffness in coronary artery disease

Abstract

Background: Lipoprotein-associated Phospholipase A2 (Lp-PLA2), has a powerful inflammatory and atherogenic action in the vascular wall and is an independent marker of poor prognosis in coronary artery disease (CAD). We investigate the association of Lp-PLA2 with markers of vascular dysfunction and atherosclerosis with proven prognostic value in CAD.

Methods: In 111 patients with angiographically documented chronic CAD, we measured 1) carotid intima-media thickness (CIMT), 2) reactive hyperemia using fingertip peripheral arterial tonometry (RH-PAT), 3) coronary flow reserve (CFR), by Doppler echocardiography 4) pulse wave velocity (PWV) and 5) blood levels of Lp-PLA2.

Results: Patients with Lp-PLA2 concentration >234.5 ng/ml (50th percentile) had higher CIMT (1.44 ± 0.07 vs. 1.06 ± 0.06 mm), PWV (11.0 ± 2.36 vs. 9.7 ± 2.38 m/s) and lower RH-PAT(1.24 ± 0.25 vs. 1.51 ± 0.53) and CFR (2.39 ± 0.75 vs. 2.9 ± 0.86) compared to those with lower Lp-PLA (p < 0.05 for all comparisons). Lp-PLA2 was positively associated with CIMT (regression coefficient b: 0.30 per unit of Lp-PLA2, p = 0.02), PWV (b:0.201, p = 0.04) and inversely with RHI-PAT (b: -0.371, p < 0.001) and CFR (b:-0.32, p = 0.002). In multivariate analysis, Lp-PLA2 was an independent determinant of RHI-PAT, CFR, CIMT and PWV in a model including age, sex, smoking, diabetes, dyslipidemia and hypertension (p < 0.05 for all vascular markers). Lp-PLA2, RHI-PAT and CFR were independent predictors of cardiac events during a 3-year follow-up.

Conclusions: Elevated Lp-PLA2 concentration is related with endothelial dysfunction, carotid atherosclerosis, impaired coronary flow reserve and increased arterial stiffness and adverse outcome in CAD patients. These findings suggest that the prognostic role of Lp-PLA2 in chronic CAD may be explained by a generalized detrimental effect of this lipase on endothelial function and arterial wall properties.

Keywords: Carotid intima-media thickness; Coronary artery disease; Coronary flow reserve; Lp-PLA2; Prognosis; Pulse wave velocity; Reactive hyperemia index.