Low Plasma Levels of Soluble Endoglin and Cardiovascular Events in Patients Undergoing Coronary Angiography

Abstract

TGF-β is recognized as playing a protective role against atherosclerosis. Endoglin is a receptor for TGF-β, and its expression is upregulated in atherosclerotic plaques. Endoglin is secreted from the cell membrane into the circulation as a soluble form (sEng). We previously reported that plasma sEng levels were low in patients with coronary artery disease (CAD). However, the prognostic value of sEng levels has not been clarified. We investigated the association between plasma sEng levels and cardiovascular events in 403 patients who had an elective coronary angiography and were then followed up. Cardiovascular events were defined as cardiovascular death, myocardial infarction, unstable angina, heart failure, stroke, or coronary revascularization. Of the 403 patients, 209 (52%) had CAD. Plasma sEng levels were lower in patients with CAD than in those without CAD (median 4.26 vs. 4.41 ng/mL, p < 0.025). During a mean follow-up period of 7.5 ± 4.5 years, cardiovascular events occurred in 79 patients. Compared with 324 patients without events, 79 with events had lower sEng levels (3.95 vs. 4.39 ng/mL) and more often had an sEng level < 3.9 ng/mL (47% vs. 28%) (p < 0.02). A Kaplan-Meier analysis showed lower event-free survival in patients with sEng < 3.9 ng/mL than in those with ≥3.9 ng/mL (p < 0.02). In a multivariate Cox proportional hazards analysis, the sEng level (<3.9 ng/mL) was an independent predictor of cardiovascular events (hazard ratio: 1.59; 95%CI: 1.01-2.49). Furthermore, only among the 209 patients with CAD, the sEng level was also a predictor of further cardiovascular events (hazard ratio: 2.07; 95%CI: 1.24-3.45). Thus, low plasma sEng levels were found to be associated with an increased risk of cardiovascular events in patients with CAD and patients undergoing coronary angiography.

Keywords: atherosclerosis; biomarker; cardiovascular events; coronary artery disease; endoglin.

Figure 1

The event-free survival from cardiovascular events in the 403 study patients. The Kaplan–Meier analysis demonstrated a lower event-free survival rate in patients with sEng level <3.9 ng/mL than in those with ≥3.9 ng/mL (p < 0.02).

Figure 2

The event-free survival from cardiovascular events in 209 patients with CAD. Among the 209 patients with CAD, the Kaplan–Meier analysis also showed a lower event-free survival rate in patients with sEng levels <3.9 ng/mL than in those with ≥3.9 ng/mL (p < 0.025).