Effects of antihypertensive treatment on platelet function in essential hypertension

Potential Protective Role of Blood Pressure-Lowering Drugs on the Balance between Hemostasis and Fibrinolysis in Hypertensive Patients at Rest and During Exercise

In patients with hypertension, the triad represented by endothelial dysfunction, platelet hyperactivity, and altered fibrinolytic function disturbs the equilibrium between hemostasis and fibrinolysis and translates into a hypercoagulable state, which underlies the risk of thrombotic complications. This article reviews the scientific evidence regarding some biological effects of antihypertensive drugs, which can protect patients from the adverse consequences of hypertensive disease, improving endothelial function, enhancing antioxidant activity, and restoring equilibrium between hemostatic and fibrinolytic factors. These protective effects appear not to be mediated through blood pressure reduction and are not shared by all molecules of the same pharmacological class.

Serum uric acid levels and inflammatory markers with respect to dipping status: A retrospective analysis of hypertensive patients with or without chronic kidney disease

BACKGROUND

The aim of this study was to evaluate serum uric acid levels, inflammatory markers [C-reactive protein (CRP), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR)] and mean platelet volume (MPV) among hypertensive patients with or without chronic kidney disease (CKD) with respect to dipping status.

METHODS

A total of 432 hypertensive patients with (n = 340) or without (n = 92) CKD who had ambulatory blood pressure monitoring recordings were included. Correlation of serum uric acid levels with inflammatory markers (CRP, PLR, NLR) was evaluated as was the logistic regression analysis for determinants of nondipper pattern.

RESULTS

Nondipper pattern was noted in 65.2% and 79.7% of non-CKD and CKD patients, respectively. Multivariate logistic regression analysis revealed that only serum uric acid (OR, 2.69; 95% CI, 1.60 to 4.52; p = 0.000), MPV (OR, 1.81; 95% CI, 1.30 to 2.53; p = 0.000), PLR (OR, 0.98; 95% CI, 0.97 to 0.99; p = 0.000), and serum albumin (OR, 0.42; 95% CI, 0.19 to 0.93; p = 0.031) were significant determinants of nondipper pattern in the overall study population.

CONCLUSION

In conclusion, our findings revealed higher prevalence of nondipper pattern in hypertensive patients with than without CKD and significantly higher levels for uric acid, CRP, MPV, PLR, and NLR among nondipper than dipper hypertensive patients with CKD. High levels for uric acid and MPV and lower levels for PLR and serum albumin were noted as significant determinants of nondipper pattern among hypertensive patients.

Platelets as Predictors of Vascular Risk: Is There a Practical Index of Platelet Activity?

Activated platelets play a role in the pathogenesis of coronary heart disease (CHD). Following activation, platelets change shape, aggregate, and release several bioactive substances. The aim of this review is to identify if there is a simple and cost-effective method that indicates platelet activation and predicts the risk of CHD and vascular events. The rationale for identifying high-risk patients is to reduce their risk of vascular events by administering appropriate and effective antiplatelet treatment, like aspirin, clopidogrel, or combination regimens. Many laboratory tests estimating platelet activity have been described. Some are relatively simple, such as spontaneous or agonist-induced platelet aggregation. Other tests include measuring the mean platelet volume (MPV) or plasma soluble P-selectin levels. Some more complex tests include flow cytometry to determine platelet GP Ilb/Illa receptors, platelet surface P-selectin, plateletmonocyte aggregates, and microparticles. Only few prospective studies assessed the predictive value of platelet activation in healthy individuals. Although the MPV seems an 'easy method, there are insufficient data supporting its ability to predict the risk of a vascular event in healthy adults. Platelet aggregation, in whole blood or in platelet-rich plasma was not consistently predictive of vascular risk. Soluble P-selectin measurement is a promising method but it needs further evaluation. Flow cytometry methods are costly, time-consuming, and need specialized equipment. Thus, they are unlikely to be useful in estimating the risk in large numbers of patients. There is as yet no ideal test for the detection of platelet activation. Each currently available test has merits and disadvantages. Simple methods such as the MPV and the determination of platelet release products need further evaluation.

Assessment of Mean Platelet Volume in Patients with Resistant Hypertension, Controlled Hypertension and Normotensives

OBJECTIVE

Patients with resistant hypertension are at increased risk for cardiovascular events. Mean platelet volume (MPV) is an accepted biomarker of platelet activation and considered as a risk factor for cardiovascular disease. The aim of this study was to determine whether MPV levels are higher in resistant hypertensive (RHTN) patients than in controlled hypertensive (CHTN) patients and healthy normotensive controls.

MATERIALS AND METHODS

279 consecutive patients were included in this study. Patients were divided into three groups: Resistant hypertension patient group [n=78; mean age 56.8±9.8; 42 males (53.8%)]; controlled hypertension patient group [n=121; mean age 54.1±9.6; 49 males (40.5%)]; and normotensive control group [n=80; mean age 49.8±8.5; 34 males (42.5%)]. Physical examination, laboratory work-up, and 24-hour ambulatory blood pressure measurement (ABPM) were performed in all participants.

RESULTS

The mean platelet volume levels were significantly higher in RHTN group than in the CHTN and normotensive groups (p<0.001). In correlation analysis office systolic and diastolic blood pressure was positively correlated with MPV.

CONCLUSION

Our study demonstrated that MPV, as an important indicator of platelet activation, was statistically higher in RHTN patients than in CHTN and in normotensive subjects. Elevated MPV levels may help to determine a high risk group for atherosclerosis in RHTN patients.

Assessment of the relation between mean platelet volume, non-dipping blood pressure pattern, and left ventricular mass index in sustained hypertension

Background

Elevated mean platelet volume may reflect presence of active large platelets, which lead to fatal or non-fatal cardiovascular events. In recent studies, lack of nocturnal blood pressure fall was presented as an independent predictor of poor prognosis in essential hypertension. The relation of raised MPV with left ventricular hypertrophy has also been reported in hypertension.

The aim of this study was to investigate the relation between MPV, non-dipping blood pressure pattern, and left ventricular mass index (LVMI) in sustained hypertension.

Material/Methods

A total of 2500 patients, whose ambulatory blood pressure (ABP) records had been evaluated retrospectively between January 2010 and December 2012, were included. Patients were divided into 3 groups according to their ABP values: non-dipper hypertensive (n=289), dipper hypertensive (n=255), and normotensive (n=306). The MPV levels and biochemical analyses were recorded from patient files and, LVMI were automatically calculated using a regression equation.

Results

The non-dipper and dipper hypertensive groups had significantly higher MPV levels than normotensives (8.4±1 fL, 8.3±1 fL, and 8.1±0.6 fL, respectively, p<0.001). However, there was no difference among the non-dipper and dipper groups in terms of MPV level (p=0.675). Although LVMI was significantly different between non-dipper, dipper, and normotensive groups (p=0.009), no correlation was found between MPV level and LVMI in dipper and non-dipper hypertensive patients (r=−0.080, p=0.142). There was a weak correlation between MPV level and ambulatory 24-h diastolic and systolic blood pressure (r=0.076, p=0.027, and r=0.073, p=0.033, respectively).

Conclusions

We demonstrated that there was no correlation between MPV level, non-dipping pattern of blood pressure, and LVMI in sustained hypertension.

Assessment of mean platelet volume and soluble CD40 ligand levels in patients with non-dipper hypertension, dippers and normotensives

Abstract Objective: Patients with a lack of nocturnal decline in blood pressure (BP) are at an increased risk for cardiovascular events. Mean platelet volume (MPV) and soluble CD40 ligand (sCD40L) are accepted biomarkers of platelet activation and considered as a risk factor for cardiovascular disease. The aim of this study was to determine whether MPV and sCD40L levels are higher in non-dipper hypertensive (NDHT) patients than in dipper hypertensive (DHT) patients and healthy controls.

METHODS

124 consecutive patients were included to this study. Patients were divided into three groups: NDHT patient group [n = 43; mean age 51.8 ± 6.6; 31 males (72.1%)]; DHT patient group [n = 41; mean age 50.2 ± 7.3; 22 males (53.7%)]; and normotensive group [n = 40; mean age 49.9 ± 6.7; 22 males (55%)]. Physical examination, laboratory work-up and 24-h ABPM were performed for all participants.

RESULTS

The sCD40L and MPV levels were significantly higher in the NDHT group than in the DHT and normotensive groups (p < 0.05). In correlation analysis, MPV, 24-h systolic blood pressure (SBP), 24-h diastolic blood pressure (DBP), night-time SBP and night-time DBP were positively correlated with sCD40L.

CONCLUSION

Our study demonstrated that MPV and sCD40L levels were significantly higher in NDHT patients compared to DHT and normotensive patients. sCD40L levels were positively correlated with MPV, 24-h SBP, 24-h DBP, night-time SBP and night-time DBP.

Effects of isotretinoin on the platelet counts and the mean platelet volume in patients with acne vulgaris

Aim. The aim of this study was to evaluate the platelet counts and the mean platelet volume in patients who received isotretinoin for the treatment of acne vulgaris. Method. A total of 110 patients were included in this retrospective study. Complete blood count parameters were recorded prior to and three-months following the treatment. Results. Both platelet counts and the mean platelet volume were significantly decreased following the treatment. No significant differences were noted on the levels of hemoglobin, hematocrit, and white blood cell count. Conclusion. Platelet counts and mean platelet volume significantly decreased following isotretinoin treatment. Since the decrease of platelet counts and the mean platelet volume was seen concomitantly, it is concluded that the effect of isotretinoin was through the suppression of bone marrow.

Thrombin activatable fibrinolysis inhibitor (TAFI) levels in hypertensive patients and a comparison of the effects of amlodipine and ramipril on TAFI levels

Hypertension is associated with fibrinolysis abnormality. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a novel molecule-linking coagulation and fibrinolysis. The aim of this study was to investigate the levels of TAFI in primary hypertensive patients and to compare the effects of amlodipine and ramipril on TAFI levels. The study was performed with 58 hypertensive subjects and 27 healthy volunteers. Biochemical and hematological parameters and TAFI levels were measured at baseline and after 1-month follow-up. TAFI concentrations increased in hypertensive patients compared with the controls (P = .030). Additionally, TAFI levels decreased with blood pressure control at 1-month follow-up (P = .026). There was no significant difference between TAFI levels in the amlodipine and ramipril groups at baseline. However, after 1-month follow-up, TAFI levels were decreased in the amlodipine group (P = .037) but not in the ramipril group. Our study is the first in the literature to determine increased TAFI levels in primary hypertension patients. In addition, we determined a decrease in TAFI levels in the amlodipine group after 1 month, but none in the ramipril group.

Cyclosporin A does not affect platelets in children with idiopathic nephrotic syndrome

The immunosuppressive agents administered to maintain the remission of idiopathic nephrotic syndrome (INS) may have a deleterious effect on several cell types. The aim of this study was to analyze platelet activation and reactivity in children with INS treated with cyclosporin A (CyA). The study groups comprised 16 children with remission of INS induced by CyA and 16 children with glucocorticosteroid-induced remission 8 weeks from the onset of INS relapse. Fifteen healthy children served as controls. Surface expression of CD61, CD62P, and CD42b on resting and thrombin-stimulated platelets was analyzed with flow cytometry. No differences between groups were found in CD61, CD62P, and CD42b surface expression, but markers of the coagulation cascade and fibrinolysis or endothelial injury (F1+2 prothrombin fragments, tissue plasminogen activator inhibitor 1) were elevated in patients treated with CyA compared with children on steroids and healthy controls. No correlations between markers of platelet function and CyA concentration were found. We postulate that CyA administration in nephrotic patients causes an activation of thrombinogenesis but does not influence platelet activation and reactivity in INS.

Is the effect of antihypertensive drugs on platelet aggregability and fibrinolysis clinically relevant?

Hypertension is associated with decreased fibrinolytic potential, mainly expressed as elevated plasma plasminogen activator inhibitor type 1 (PAI-1) levels, and increased platelet aggregability, which may account in part for the increased risk of atherosclerosis and its clinical complications in hypertensive patients. The effects of antihypertensive drugs on this prothrombotic state have been investigated and controversial findings have been reported, possibly because of differences in study designs, patients selected, and methodology used. Scarce and conflicting data exist about the effects of diuretics and beta-adrenoceptor antagonists on the fibrinolytic system, whereas ACE inhibitors have generally been reported to improve the fibrinolytic balance by decreasing plasma PAI-1 levels, calcium channel antagonists have been shown to increase tissue plasminogen activator (tPA) activity, and angiotensin II type 1 (AT(1)) receptor antagonists seem to exert neutral effects. beta-Adrenoceptor antagonists, calcium channel antagonists, and AT(1)-receptor antagonists have been reported to exert anti-aggregatory effects on platelets, while contrasting data exist about the influence of ACE inhibitors. Clinical implications of the changes induced by antihypertensive drugs on the fibrinolytic balance and platelet function are still debated. In particular, the question of whether these changes may translate into different degrees of cardiovascular protection in hypertensive patients remains unanswered. While awaiting more information from clinical trials, the choice of antihypertensive drugs, particularly in high-risk patients, should take into account effects beyond their BP-lowering efficacy. Selected agents should have a favorable, or at least neutral, impact on fibrinolytic function and platelet activity.

Platelet morphology and plasma indices of platelet activation in essential hypertension: effects of amlodipine-based antihypertensive therapy

BACKGROUND AND AIM

Platelet abnormalities have been described in hypertension, especially in the presence of target organ damage. Our aim was to study the differences in morphology and indices of platelet activation in treatment-naive patients with essential hypertension as compared to normotensive controls and secondly, to study the effects of amlodipine-based antihypertensive therapy on these indices.

METHODS

We recruited 42 previously untreated, newly diagnosed hypertensive patients (25 men; mean age 53 years) for the cross-sectional study, where data were compared with those from 30 normotensive controls (20 men; mean age 57 years). Of the 42 untreated hypertensive patients who were recruited, 27 patients successfully completed, the six-month treatment phase with amlodipine-based antihypertensive therapy. Platelet morphology (volume and mass) was quantified, and plasma markers of platelet activation (betaTG and sPsel) measured in citrated plasma. The mass of P-selectin in each platelet (pPsel) was determined by lysing a fixed number of platelets and then determining the levels of P-selectin in the lysate.

RESULTS

Hypertensive patients had significantly higher platelet volume (P = 0.01) and mass (P = 0.003), plasma betaTG and sPsel, and pPsel levels (all P < 0.001) compared to the controls. After a mean treatment time of 6 months, there was a decrease in platelet volume (P < 0.001) and mass (P = 0.02), with lower pPsel, sPsel and BTG levels (all P < 0.001) compared to the untreated state.

CONCLUSION

Treatment of uncomplicated essential hypertension using amlodipine-based anti-hypertensive therapy results in a reversal of the platelet morphology abnormalities and indices of platelet activation. This may contribute to a reduction in thrombosis-related complications seen in those whose blood pressure lowering is effective.

Effects of efonidipine on platelet and monocyte activation markers in hypertensive patients with and without type 2 diabetes mellitus

We compared the levels of microparticles, platelet activation markers, soluble cell adhesion molecules, and soluble selectins between hypertensive patients with and without type 2 diabetes and control subjects. Binding of anti-glycoprotein IIb/IIIa and anti-glycoprotein Ib monoclonal antibodies to platelets did not differ significantly between the hypertensive patients and controls, but platelet expression of activation markers (CD62P, CD63, PAC-1, and annexin V) was higher in the hypertensive patients. Platelet-derived microparticle (PDMP) and monocyte-derived microparticle (MDMP) levels were significantly higher in the hypertensive patients than in the controls. Soluble ICAM-1, VCAM-1, P-selectin, and E-selectin levels were also higher in the hypertensive patients, and they were significantly higher in the hypertensive patients with diabetes. After treatment with efonidipine, the levels of PDMPs, CD62P-, CD63-, PAC-1-, and annexin V-positive platelets, sICAM-1, sVCAM-1, sP-selectin, and sE-selectin all decreased significantly. The MDMP levels decreased, and the decrease was significant in the hypertensive patients with diabetes. These findings suggest that administration of efonidipine to hypertension patients with diabetes may prevent the development of cardiovascular complications caused by cell adhesion molecules or activated platelets and monocytes.

Cilnidipine more highly attenuates cold pressor stress-induced platelet activation in hypertension than does amlodipine

The clinical significance of N-type calcium channel blockade has not been fully examined. We here compared the effects of the N-type calcium channel blockers cilnidipine and amlodipine on the sympathetic nervous system and platelet function in hypertension under resting and stressed conditions. Thirty-two patients with hypertension (58+/-9 years) received cilnidipine or amlodipine for 4 weeks in this crossover study. On day 28 of each treatment, plasma levels of epinephrine (EP), norepinephrine (NEP), and beta-thromboglobulin (BTG), and EC50 of ADP-induced platelet aggregation (ADPE50) were determined at rest and after a cold pressor test. On day 29, the group receiving cilnidipine was switched to amlodipine treatment, and vice versa. At rest, the blood pressure, heart rates, EP, NEP, ADPEC50, and BTG, were similar in both treatments. After the cold pressor test, increases in EP (35+/-17 to 44+/-25 pg/ml; p<0.05) and BTG (40+/-13 to 49+/-22 ng/ml; p<0.01) and a decrease in ADPEC50 (32+/-26 to 27+/-24 micromol; p<0.05) were observed in the amlodipine treatment, but not in the cilnidipine treatment. In addition, the increase in NEP was significantly greater (p<0.05) in the amlodipine (276+/-78 to 318+/-87 pg/ml; p<0.01) than in the cilnidipine treatment (273+/-88 to 291+/-100 pg/ml; p<0.05). Cilnidipine more highly attenuates the activation of platelet function in response to cold pressor stress than does amlodipine. Attenuated activation of the sympathetic nervous system via N-type calcium channel blockade may contribute to this phenomenon.