Evaluation of Whole Blood Viscosity in Patients with Aortic Sclerosis

Background: Blood viscosity and aortic sclerosis (AS) are strong predictors of cardiovascular events. The effects of blood viscosity on AS have not been studied adequately. We aimed to investigate the potential connection between whole blood viscosity (WBV) and AS. Methods: AS was detected by transthoracic echocardiography. The estimation of WBV was carried out at both high shear rate (HSR) (208/s) and low shear rate (LSR) (0.5/s) by previously validated formulae using hematocrit (HcT) and total protein (TP) in g/L. WBV at HSR (208/s) is: (0.12 × HcT) + 0.17 (TP - 2.07) and WBV at LSR (0.5/s) is: (1.89 × HcT) + 3.76 (TP - 78.42). Comparisons of WBV at both HSR and LSR were made between patients with and without AS. Results: We included 94 patients with AS (male = 30.9%, mean age = 67.5 y) and 97 control subjects without AS (male =26.6%, mean age = 69.1 y). Almost all of the clinical, echocardiographic, and biochemical characteristics were similar, but TP values were significantly higher in the AS group than in the control group (72.9 ± 5 g/L vs. 75.8 ± 6.1 g/L; p value < 0.001). Hemoglobin and HcT levels were similar (p value = 0.604 and p value = 0.431, respectively). In the AS group, WBV at LSR and HSR was higher than that in the control group (p value = 0.001 for both LSR and HSR). In multiple stepwise logistic regression analysis, WBV was an independent predictor of AS (p value < 0.001). Conclusion: We found higher WBV in patients with AS than in patients without AS at both LSR (0.5/s) and HSR (208/s). WBV at both LSR and HSR was independently associated with AS.