Prognostic significance of whole blood viscosity estimated by de Simone’s formula in ST-elevation myocardial infarction

Whole Blood Viscosity and Cerebral Blood Flow in Acute Ischemic Stroke

Existing effective treatments for ischemic stroke restore blood supply to the ischemic region using thrombolysis or mechanical removal of clot. However, it is increasingly recognized that successful removal of occlusive thrombus from the large artery-recanalization, may not always be accompanied by successful restoration of blood flow to the downstream tissues-reperfusion. Ultimately, brain tissue survival depends on cerebral perfusion, and a functioning microcirculation. Because capillary diameter is often equal to or smaller than an erythrocyte, microcirculation is largely dependent on erythrocyte rheological (hemorheological) factors such as whole blood viscosity (WBV). Several studies in the past have demonstrated elevated WBV in stroke compared with healthy controls. Also, elevated WBV has shown to be an independent risk factor for stroke. Elevated WBV leads to endothelial dysfunction, decreases nitric oxide-dependent flow-mediated vasodilation, and promotes hemostatic alterations/thrombosis, all leading to microcirculation sludging. Compromised microcirculation further leads to decreased cerebral perfusion. Hence, modulating WBV through pharmacological agents might be beneficial to improve cerebral perfusion in stroke. This review discusses the effect of elevated WBV on endothelial function, hemostatic alterations, and thrombosis leading to reduced cerebral perfusion in stroke.

Mendelian randomization study of whole blood viscosity and cardiovascular diseases

AIMS

Association between whole blood viscosity (WBV) and an increased risk of cardiovascular disease (CVD) has been reported. However, the causal relationship between WBV and CVD remains not thoroughly investigated. The aim of this study was to investigate the causal relation between WBV and CVD.

METHODS

Two-sample Mendelian randomization (MR) was employed, with inverse variance weighting (IVW) as the primary method, to investigate the casual relationship between WBV and CVD. The calculated WBV and medical records of 378,210 individuals participating in the UK Biobank study were divided into halves and analyzed.

RESULTS

The means of calculated WBVs were 16.9 (standard deviation: 0.8) and 55.1 (standard deviation: 17.2) for high shear rate (HSR) and low shear rate (LSR), respectively. 37,859 (10.0%) major cardiovascular events (MACE) consisted of 23,894 (6.3%) cases of myocardial infarction (MI), 9,245 (2.4%) cases of ischemic stroke, 10,377 (2.7%) cases of revascularization, and 5,703 (1.5%) cases of coronary heart disease-related death. In the MR analysis, no evidence was found indicating a causal effect of WBV on MACE (IVW p-value for HSR = 0.81, IVW p-value for LSR = 0.47), MI (0.92, 0.83), ischemic stroke (0.52, 0.74), revascularization (0.71, 0.54), and coronary heart disease-related death (0.83, 0.70). The lack of sufficient evidence for causality persisted in other MR methods, including weighted median and MR-egger.

CONCLUSIONS

The Mendelian randomization analysis conducted in this study does not support a causal relationship between calculated WBV and CVD.

Relationship between blood viscosity and thrombus burden in ST-segment elevation myocardial infarction

BACKGROUND

İncreased whole blood viscosity (WBV) is associated with increased infarct area, impaired microvascular circulation and mortality in patients with ST-elevation myocardial infarction (STEMI).

OBJECTIVES

We aimed to analyze the association between the WBV and thrombus burden (TB) in STEMI patients.

METHODS

This cross-sectional study included 167 STEMI patients who received primary percutaneous coronary intervention. WBV values were assessed using hematocrit and total protein values, and low shear rate(LSR) and high shear rate(HSR) were calculated. Angiographic TB was assessed according to the definition of the Thrombolysis in Myocardial Infarction (TIMI) study group. The cases were dichotomized into low TB (grade 1-3) (n = 87) and high TB (grade 4-5) (n = 80) groups.

RESULTS

The mean HSR and LSR values of the high TB group were significantly increased compared to the low TB group (p < 0.001, for each). In ROC analysis,for prediction of TB, a cut-off value of 3.83 WBV for HSR had a 71% sensitivity and a 60.7% specificity, and a cut-off value of 21 WBV for LSR had a 70% sensitivity and 59.9% specificity (p < 0.001,for each). Multivariate regression analysis showed that both HSR (OR = 2.408;p=0.020) and LSR (OR = 1.055;p=0.021) were independent predictors for high TB.

CONCLUSION

İncreased WBV was an independent predictor for the presence of high TB in patients with STEMI.

Whole blood viscosity in patients with aortic stenosis

Whole blood viscosity (WBV) may promote endothelial shear stress, inflammation, and can accelerate the atherosclerotic process. We aimed to evaluate the relationship between WBV and aortic stenosis. The study included 209 participants of whom 49 patients had severe aortic stenosis, 98 patients had mild-to-moderate aortic stenosis and 62 patients served as control. WBV values were significantly higher for high shear rate (HSR) (P = 0.001) and for low shear rate (LSR) (P = 0.002) in severe aortic stenosis group. HSR and LSR were correlated with mean systolic transaortic gradient (P < 0.001 and P < 0.001, respectively). WBV for both LSR and HSR were found to be independent predictors for the aortic stenosis severity (P = 0.034 and P = 0.049, respectively). We found a significant relationship between WBV and aortic stenosis.

Relationship between blood viscosity and no-reflow phenomenon in ST-segment elevation myocardial infarction performed in primary percutaneous coronary interventions

Background: This study aimed to analyze the associations between no-reflow (NR) phenomenon development and whole-blood viscosity in patients with ST-elevated myocardial infarction. Methods: A total of 217 patients with ST-elevated myocardial infarction were included. whole-blood viscosity values were assessed using hematocrit and total protein values, and low shear rate (LSR) and high shear rate (HSR) were calculated. Results: The average LSR and HSR values of the study group were significantly higher than the control group (p < 0.001). Multivariate logistic regression analysis showed that both HSR (odds ratio: 4.957; p < 0.001) and LSR (odds ratio: 1.114; p < 0.001) were independent predictors for NR development. Conclusion: This study found that increased blood viscosity was an independent predictor for NR development.

Whole blood viscosity predicts nondipping circadian pattern in essential hypertension

Aim: We aimed to investigate the association between whole blood viscosity (WBV) and nondipping pattern in patients with essential hypertension. Materials & methods: A total of consecutive 530 patients who had been evaluated by ambulatory blood pressure monitoring were included. WBV was estimated by using hematocrit and plasma total protein levels for both WBV in low shear rate (0.5 s-1) and WBV in high shear rate (208 s-1) according to the de Simone's formula. Results: In the multivariate analysis, low shear rate and high shear rate of WBV were associated independently with nondipping pattern in patients with essential hypertension. Conclusion: As a simple, inexpensive and noninvasive tool, WBV seems to be a significant predictor of nondipping hypertension.

The Relationship between Blood Viscosity and Acute Arterial Occlusion

Background: Blood viscosity is a strong predictor of cardiovascular events. However, the relationship between blood viscosity and acute arterial occlusion (AAO) has not been studied adequately so far.

Objectives: The aim of the present study was to assess the relationship between whole blood viscosity (WBV) and AAO.

Material and methods: The study included 93 patients who were diagnosed with AAO between January 2017 and September 2019, and 90 age- and sex-matched healthy controls. WBV was assessed using a validated calculation formula derived from hematocrit and total plasma protein levels, both as a low (LSR) and a high (HSR) shear rate.

Results: There were no significant differences between the two groups in regards to the baseline characteristics, with the exception of smoking and LDL cholesterol levels. Subjects with AAO presented significantly higher WBV values both at LSR (32.2 ± 5.0 vs. 26.6 ± 5.0, p <0.001) and HSR (6.2 ± 0.3 vs. 5.7 ± 0.3, p <0.001). The ROC analysis revealed a cut-off value of 27.4 for WBV at LSR (sensitivity 66%, specificity 64%, AUC = 0.770, p <0.001) and a cut-off value of 5.29 in case of HSR (sensitivity 69%, specificity 74%, AUC = 0.801, p <0.001) for predicting AAO. Multivariate analysis, both LSR (OR 3.33, 95% CI: 1.20–9.43, p = 0.006) and HSR (p = 0.020, OR: 1.70, 95% CI: 1.020–1.123) were independent predictors of AAO.

Conclusions: This study demonstrated that WBV levels at both HSR and LSR are significantly higher in the AAO group than in the control subjects, indicating that an increased WBV may be associated with the development of AAO.

Relationship between apical thrombus formation and blood viscosity in acute anterior myocardial infarction patients

Aim: This study sought to investigate the predictive value of whole blood viscosity (WBV) to identify high-risk patients who will develop an apical thrombus during the acute phase of anterior transmural infarction. Materials & methods: Consecutive 1726 patients with first acute anterior myocardial infarction were evaluated. WBV was calculated according to the Simone’s formula. Results: Patients with an apical thrombus had prolonged pain to balloon time, higher rate of post-PCI thrombolysis in myocardial infarction flow ≤1 and significantly higher mean WBV values at both shear rates than those without an apical thrombus. Conclusion: WBV values at both shear rates were found to be significant and independent predictors for early LV apical thrombus formation complicating a first-ever anterior wall myocardial infarction.

Serum osmolarity and blood viscosity as a potential explanation for the pathophysiology of neuroleptic malignant syndrome

Background: Neuroleptic malignant syndrome (NMS) is a rare but life-threatening side effect. NMS patients usually develop dehydration and fluid-electrolyte imbalance. In this study, we aimed to investigate serum osmolarity and blood viscosity in patients with NMS.Methods: This was a retrospective case-control study including 32 admissions of 27 patients with the diagnosis of NMS. As a control group, 31 non-NMS episodes of hospitalizations of the same patients were included.Results: Serum osmolarity of NMS group was 301.83 ± 20.27 mOsm/L and control group was 294.20 ± 5.92 mOsm/L. Serum osmolarity of NMS group was statistically significantly higher than the controls (p = .018). Whole blood viscosity (WBV) at high shear rate (HSR) value of NMS group was 16.17 ± 1.48 and control group was 16.50 ± 1.38 (p = .331). Regarding WBV at low shear rate (LSR) values, also no statistically significant difference was observed between groups. LSR values of NMS and control group were 39.86 ± 30.11 and 47.41 ± 28.43, respectively (p = .387).Conclusions: Our findings indicate that serum osmolarity of NMS group was statistically significantly higher than the controls. In terms of blood viscosity, there was no statistically significant difference between groups. Higher serum osmolarity in NMS patients than controls may be a reflection of a relative hemoconcentration in NMS.KEY POINTSNMS is usually associated with dehydration resulting in fluid-electrolyte imbalance.We compared the NMS episodes with non-NMS hospitalizations (as control group) of the same patients.Serum osmolarity was statistically significantly higher in NMS group than the controls.There was no statistically significant difference between groups in terms of blood viscosity.

Usefulness of the whole blood viscosity to predict stent thrombosis in ST-elevation myocardial infarction

Aim: This study sought to investigate the predictive value of estimated whole blood viscosity (WBV) for stent thrombosis (ST) in ST-elevation myocardial infarction (STEMI) patients who underwent percutaneous coronary intervention. Materials & methods: A total of 1720 STEMI patients treated with primary percutaneous coronary intervention were followed up for median 36.0 months. WBV was calculated according to the Simone's formula. Results: During follow-up period, 119 patients were diagnosed as 'definite' ST. The rate of ST was significantly higher in the high WBV group. In multivariate analysis, adjusted for other factors, higher WBV significantly increased risk of ST at both shear rates. Conclusion: Being an easily accessible and costless parameter, WBV seems to be an emerging predictor of ST in patients with STEMI.

The association of estimated whole blood viscosity with hemodynamic parameters and prognosis in patients with heart failure

AIM

We aimed to investigate the association of estimated whole blood viscosity (WBV) with hemodynamic parameters and prognosis in patients with heart failure with reduced ejection fraction.

MATERIALS & METHODS

Total of 542 patients were included and followed-up for median 13 months.

RESULTS

The WBV parameters had negative relationship with right atrium pressure and positive correlation with cardiac index. The WBV parameters were found to be independent predictors of composite end point (CEP) and all-cause mortality. Every one cP increases of WBV(h) and WBV(l) were associated with 17 and 1% reductions of CEP. In Kaplan-Meier analysis, patients with low WBV quartiles were found to have significantly more CEP.

CONCLUSION

Being an easily accessible and costless prognosticator, WBV seems to be a novel marker for determining prognosis and an emerging tool to individualize heart failure with reduced ejection fraction management.

Does Blood Flow Change according to Mood? Blood Rheology in Bipolar Disorder

Objective

Bipolar disorder (BD) is associated with increased rates of cardiovascular diseases. There is growing evidence that blood viscosity may have a common role, correlated with well-known major risk factors that promote cardiovascular disease. In this study we aimed to investigate the whole blood viscosity (WBV) in different stages of BD.

Methods

A total of 121 bipolar patients and 41 age-gender matched healthy controls were included. Forty-four of bipolar patients were in manic, 35 were depressed and 42 were in euthymic state. WBV was calculated from hematocrit and total plasma protein according to Simone's formula at low and high shear rates (LSR and HSR).

Results

WBV at HSR of manic group was 16.91±1.01, depressive group was 17.23±0.80, euthymic group was 17.63±0.95, and control group was 17.52±0.71 (p =0.001). WBV at LSR of manic depressive, euthymic and control group were 53.10±20.58, 60.30±17.02, 8.91±20.33, and 62.01±19.28, respectively (p =0.001). Both WBV at HSR and LSR of manic group was significantly lower than that of the euthymic and control groups (p =0.001 and 0.010 respectively for HSR, p =0.001 and 0.011 respectively for LSR). WBV was significantly positively correlated with lipid profile except high density lipoprotein (HDL).

Conclusion

Our results demonstrate a decrement in blood viscosity in manic episode compared with euthymics and controls. Positive correlation of blood viscosity with lipid parameters (except HDL), and negative correlation with number of previous manic episodes suggest that manic episode has favorable effect on cardiovascular risk regarding to blood viscosity.

The Contribution of Whole Blood Viscosity to the Process of Aortic Valve Sclerosis

OBJECTIVE

We aimed to investigate whether increased whole blood viscosity (WBV) could be an important factor for the occurrence of aortic valve sclerosis (AVS).

SUBJECTS AND METHODS

A total of 209 patients were enrolled in the study. WBV was calculated using the hematocrit and total plasma protein at a low shear rate (LSR) and a high shear rate (HSR). AVS was defined as irregular valve thickening and calcification (without evidence of outflow obstruction) documented by a peak transvalvular velocity < 2.5 m/s on echocardiographic examination. The patient group consisted of 109 patients with AVS (77 females, 32 males), and 100 subjects without AVS (65 females, 35 males) were assigned to the control group.

RESULTS

In the AVS group, WBV values were significantly higher for HSR (17.4 ± 0.5 vs. 17.1 ± 0.7 208 s-1, p < 0.001) and LSR (65.9 ± 12.5 vs. 59.7 ± 16.7 0.5 s-1, p = 0.002). In multivariate logistic regression analysis, WBV at HSR and LSR were independent predictors of AVS (odds ratio, OR: 2.24, 95% confidence interval, CI: 1.38-3.64, p = 0.001; OR: 1.026, 95% CI: 1.006-1.046, p = 0.01, respectively). Receiver-operating characteristic (ROC) curve analysis indicated that a WBV cutoff value of 65.4 at LSR had a sensitivity of 46.8% and a specificity of 60.0% (area under the ROC curve, AUC: 0.615, 95% CI: 0.535-0.696, p = 0.004), and a WBV cutoff value of 17.1 at HSR had a sensitivity of 61.5% and specificity of 53% (AUC: 0.648, 95% CI: 0.571-0.725, p < 0.001) for the prediction of AVS.

CONCLUSION

This study demonstrated that WBV was independently associated with AVS. WBV could be an indicator of inflammation and vessel remodeling without evidence of outflow obstruction.