BACKGROUND
As an important inflammatory factor and a key participant in coagulation, fibrinogen has attracted attention in the management of acute coronary syndrome (ACS). However, the relationship between the fibrinogen level and the prognosis of patients with ACS remains controversial.In addition, the quantitative relationship between fibrinogen and the risk of mortality in a longer follow-up period needs further clarification.
OBJECTIVE
We aim to investigate the dose-effect of fibrinogen on ACS long-term prognoses with a prospective, large-scale, single-centre registry study.
METHODS
Patients were grouped by the five quantile levels of the plasma fibrinogen at admission. We used the Kaplan-Meier analysis to estimate the cumulative incidence of all-cause mortality. The predictive value of the fibrinogen level for the 10-year mortality was estimated by a Cox proportional hazards regression model. The impact of the fibrinogen on the 10-year mortality was assessed by a restricted cubic spline (RCS) curve, which was derived from an adjusted Cox proportional hazards regression model.
RESULTS
A total of 2405 consecutive ACS patients admitted to the West China Hospital between December 10th, 2010, and December 31st, 2012, were enrolled in this study. In the Kaplan-Meier analysis, the cumulative incidence of mortality was significantly different among the five groups (log-rank test: P<.001). Group 2 (fibrinogen level: 2.63-3.04 g/L) had the lowest incidence of mortality). In the Cox univariate regression analysis, fibrinogen was identified as an independent risk factor for the 10-year mortality (HR: 1.24 (1.15-1.35), P<.001).The RCS curve suggested strong U-shaped relationships between the adjusted risk of the 10-year mortality and the fibrinogen level, which was in accordance with the trend found in the Kaplan-Meier analysis. The risk of all-cause mortality decreased until the fibrinogen reached 2.81 g/L, and it then started to increase afterwards (P for nonlinearity <.001).
CONCLUSIONS
The long-term follow-up of nearly a decade and the quantitative RCS analysis suggested that the fibrinogen levels at admission have a significant impact on the long-term prognosis of ACS patients. The mechanisms underlying this phenomenon may be that fibrinogen acts as both an acute-phase protein and a subclinical inflammatory indicator. As an acute-phase protein, the fibrinogen level reflects the rupture of atherosclerotic plaques, while as a subclinical inflammatory indicator, it is involved in other metabolic processes, such as carbohydrate metabolism. Both of these mechanisms may contribute to its impact on the patients' long-term prognoses.The U-shape relationship between fibrinogen level and 10-year mortality suggested the need for long-term anti-inflammatory or metabolism treatment and the need to determine the fibrinogen level in patients with ACS.