Ratio of Apolipoprotein A-II/B Improves Risk Prediction of Postoperative Survival After Carotid Endarterectomy.

ABSTRACT

BACKGROUND AND PURPOSE: Even in patients with high-grade carotid stenosis, cardiovascular morbidity causes more deaths than strokes do. Despite successful low-density lipoprotein (LDL) cholesterol lowering, a significant risk of atherosclerotic cardiovascular disease remains, eventually rendering other lipid or lipoprotein ratios more efficient treatment targets. This study aimed to investigate the predictive value of the ratio of serum apolipoprotein A-II/B for overall mortality (primary outcome) of carotid surgery patients. METHODS: This single-center, nonrandomized, prospective cohort study comprised 327 consecutive patients undergoing carotid endarterectomy for high-grade internal carotid artery stenosis. Baseline lipoprotein concentrations were measured, and patients were observed for the occurrence of the primary outcome until the census date (January, 2003 to January, 2012; median follow-up, 102.3 months). RESULTS: The ratio of apolipoprotein A-II/B (hazard ratio, 0.74 per SD; confidence interval, 0.60-0.91; P=0.004) showed the highest association with the primary outcome compared with other lipid-risk parameters, significantly improving a prognostic model based on major cardiovascular risk factors, including LDL, high-density lipoprotein, and triglycerides in terms of overall performance, calibration, and discrimination. This led to a significantly improved reclassification of 8.9% of all patients (net reclassification improvement, 0.137; P=0.006 and integrated discrimination improvement, 0.041; P<0.001) and of 13.6% of patients with a serum baseline concentration of <100 mg/dL LDL (net reclassification improvement, 0.270; P=0.030 and integrated discrimination improvement, 0.061; P=0.002). CONCLUSIONS: Apolipoprotein A-II/B significantly improves risk prediction of overall survival, also in carotid surgery patients with lower LDL levels. Consequently, this ratio might provide an efficient diagnostic tool and eventually a treatment target for actual lipid-lowering therapies, which has to be addressed in future randomized controlled trials.