Prognostic value of neutrophils in patients with asymptomatic carotid artery disease

Background: Inflammation is associated with atherosclerotic disease. In this context, it has been shown that an increased neutrophil count is a risk factor for cardiovascular events in patients with coronary and peripheral artery disease. However, the impact of neutrophils on long-term mortality in patients with carotid atherosclerosis is not yet fully understood.

Methods: We prospectively studied 853 of 1268 consecutive patients with neurologically asymptomatic carotid stenosis for all-cause and cardiovascular death, respectively.

Results: During a median follow-up time of 6.3 years (IQR 5.8-6.7 years) a total of 203 deaths (23.8%), including 134 cardiovascular deaths (15.7%), were recorded. An increase of 1 G/L of neutrophil count indicated an increased risk for all-cause mortality of 1.20 (CI [95%] 1.10-1.31, P < 0.001) and of cardiovascular death of 1.30 (CI 1.17-1.45, P < 0.001), respectively. For the second to the fourth quartile of the neutrophil count, adjusted hazard ratios for all-cause mortality were 1.12 (CI, 0.71-1.75), 1.46 (CI, 0.96-2.21), and 1.76 (CI, 1.15-2.69; P = 0.03 for trend); and 1.41 (CI, 0.80-2.49), 1.53 (CI, 0.88-2.68), and 2.54 (CI, 1.49-4.33; P < 0.01 for trend) for cardiovascular mortality, compared to the lowest quartile, respectively. Patients with baseline carotid stenosis of more than 50% and/or increased neutrophil count (≥median), had a 1.9-2.4 fold increase in risk of (CV-) death, compared to patients with carotid narrowing of less than 50% and/or neutrophil count less than the median (P < 0.001). After adjusting for cardiovascular risk factors, only neutrophils, but not eosinophils, basophils, monocytes, lymphocytes, or the total leukocyte count showed a significant association with long-term mortality. No significant association was found between white blood cell subtypes with either baseline degree or progression during a 6 month follow-up of carotid stenosis.

Conclusion: The baseline neutrophil count was an independent predictor for all-cause and cardiovascular mortality in neurologically asymptomatic patients with carotid stenosis. Thus, the measurement of neutrophils could provide prognostic information on outcome in patients at risk.