To the best of our knowledge, this is the first study that evaluated the potential diagnosis performance of NLR and FIB in patients with TBAD. This study found that preoperative NLR and FIB were higher in patients with TBAD compared to both aortic aneurysm and healthy participants. NLR and FIB showed excellent specificity, which was different from previous published diagnostic biomarkers. Just as we suspected NLR and FIB maybe a powerful indicator in improving diagnostic accuracy for TBAD.
Biomarkers were widely used in cardiovascular diseases because of their low cost, easy availability and less waiting time. Previous studies presented that D-dimer had excellent sensitivity but modest specificity diagnostic performance. Troponin T can be used for early risk stratification of patients with acute type A aortic dissection18. White blood cells and N-terminal pro-brain natriuretic peptide were suggested for early diagnosis of aortic dissection19. In this study, NLR and FIB showed wonderful specificity, that maybe a powerful complementary with the existing biomarkers to improve the diagnostic value.
Compared with neutrophil count, lymphocyte count, NLR is more stable in the prediction of aortic disease. Studies have shown that there is a significant correlation between NLR and systemic inflammation20. Accumulating evidence has shown the value of NLR in evaluating the prognosis of aortic diseases21-24. Elevated NLR is also positively associated with the development of hypertension, stroke, and acute myocardial infarction (AMI)25-28. Aurelian et al. found that NLR is significantly higher among patients with infrarenal abdominal aortic aneurysm (rAAA) and that an NLR >5 indicates a 5 times greater possibility of AAA being ruptured29. However, the prognostic capacity of NLR on admission is yet to be clarified in patients with type B AAD. Fibrinogen is associated with preoperative hypoxemia in patients with aortic dissection30. Low preoperative fibrinogen level is a risk factor for neurological complications and in-hospital mortality in patients with acute aortic dissection31,32. In addition, studies have shown that fibrinogen-fibrin degradation product level at admission can be used as a predictor of aortic growth and poor one-year outcome in uncomplicated type B aortic dissection33,34. This is the first study that evaluated the potential diagnosis performance of FIB in patients with TBAD.
The function and mechanism of NLR in TBAD morbidity are still unclear. Elevated neutrophils interaction with endothelial cells leading to vascular intima injury. In addition, inflammatory cells can increase matrix metalloproteinases, which can degrade collagen and elastin, resulting in structural destruction of the aortic wall, resulting in aortic dissection35,36. Fibrinogen is an important protein in the process of coagulation and hemostasis. It can be abnormally elevated during infection, trauma, inflammation, surgery or tumor as a direct coagulation factor involved in the coagulation process. The coagulation disorder of patients with acute aortic dissection can be improved by further increasing the level of fibrinogen before operation37. When vascular endothelial cells are damaged in patients with aortic dissection, the increase of fibrinogen can be caused by endogenous and exogenous coagulation pathways38. This study shows that the level of fibrinogen in patients with aortic dissection is significantly higher than that in other groups, suggesting that the coagulation function of patients with aortic dissection is enhanced, which is helpful for pseudocavitary thromboembolization39.
This study is the first to combine NLR and FIB in the diagnosis of type B aortic dissection, which has a high clinical application value. However, there are still several disadvantages in this study: (1) the sample size of patients with non-aortic dissection is small; (2) This study is retrospective observational study; (3) Further studies are needed to understand the diagnostic role of NLR and FIB in type B aortic dissection, including combined use with other biomarkers.