Synergetic impact of lipoprotein(a) and fibrinogen on stroke in coronary artery disease patients

Background: Emerging data suggested that lipoprotein(a) [Lp(a)] is an independent risk factor for atherosclerotic cardiovascular disease. Previous studies indicated fibrinogen (Fib) had synergetic effect on Lp(a)-induced events. However, combined impact of Fib and Lp(a) on ischemic stroke has not been elucidated. Methods: In this prospective study, we consecutively enrolled 8263 patients with stable coronary artery diseases (CAD) from 2011 to 2017. Patients were categorized into three groups according to tertiles of Lp(a) levels [Lp(a)-low, Lp(a)-medium, and Lp(a)-high] and further divided into nine groups by Lp(a) and Fib levels. All subjects were followed up for the occurrence of ischemic stroke. Results: During a median follow-up of 37.7 months, 157 (1.9%) ischemic strokes occurred. Stroke incidence increased by Lp(a) (1.1 vs. 2.1 vs. 2.5%, Cochran-Armitage p < .001) and Fib (1.1 vs. 2.0 vs. 2.6%, Cochran-Armitage p < .001) categories. When further classified into nine groups by Lp(a) and Fib levels, the incidence of ischemic stroke in group 9 [Lp(a)-high and Fib-high] was significantly higher than that in group 1 [Lp(a)-low and Fib-low] (3.1 vs. 6%, p < .001). The group 9 was associated with a highest risk for ischemic stroke (adjusted HR 4.907, 95% CI: 2.154-11.18, p < .001), compared with individuals in the Lp(a)-high (adjusted HR 2.290, 95% CI: 1.483-3.537, p < .001) or Fib-high (adjusted HR 1.184, 95% CI: 1.399-3.410, p = .001). Furthermore, combining Lp(a) with Fib increased C-statistics by .045 (p = .004). Conclusions: Current study first demonstrated that elevated Lp(a) combining with Fib evaluation enhanced the risk of ischemic stroke in patients with CAD beyond Lp(a) or Fib alone.