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Elevated Blood Viscosity Raises Cardiovascular Risk

Study Shows Blood Viscosity Linked to Heart Attacks and Strokes

Research published in the European Journal of Clinical Investigationsuggests that elevated blood viscosity increases the risk for heart attacks and strokes by 342% in men with high blood pressure.

The findings are based on a study of 331 men between 40 and 64 years of age who were newly diagnosed with essential hypertension, then followed for up to 12 years.  Researchers grouped patients into three categories by their diastolic whole blood viscosity (“WBV”) levels:  top-tertile diastolic blood viscosity (WBV > 243), middle tertile (228 < WBV < 243), and bottom tertile (WBV < 228), (all units in millipoise [mP]).  The highest blood viscosity group had more than a threefold risk of cardiovascular events than the lowest blood viscosity group (hazard ratio = 3.42, 95% confidence interval = 1.40-8.38, p-value = 0.006).  

In the 331 men with high blood pressure who were studied, there were 42 first cardiovascular events, specifically, 9 subjects with myocardial infarction, 14 with unstable angina, and 19 with acute stroke.  

The study authors wrote:  “Whole blood viscosity, an overall measure of flow resistance of bulk blood, depends on several factors, including cell concentration, cell aggregation, cell deformability and plasma viscosity.  In our data, both WBV and hematocrit were univariate predictors of cardiovascular morbidity but only the former came out as an independent risk factor in a multivariate analysis, thus supporting the perspective that low-shear-rate (diastolic) WBV as a global marker of the whole-blood rheological properties may be a better discriminant of cardiovascular risk in hypertensive men.”  

The researchers concluded that their findings highlighted the role of blood viscosity in impairing microcirculation and that a “vicious cycle” may exist in which impaired microcirculation maintains, or even amplifies, an initial increase in blood pressure.  

The report states:  “This study has documented the powerful independent association between WBV at low shear rate (diastolic) and cardiovascular events.” (Ed. note. parentheses added)


G. Ciuffetti, et al. Prognostic Impact of Low-Shear Whole Blood Viscosity in Hypertensive Men.  European Journal of Clinical Investigation, 2005:35(2), 93-98.


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