Antiplatelet therapy in the management of cardiovascular disease in patients with CKD: what is the evidence?

Anticoagulation in Chronic Kidney Disease

The nuanced landscape of anticoagulation therapy in patients with chronic kidney disease (CKD) presents a formidable challenge, intricately balancing the dual hazards of hemorrhage and thrombosis. These patients find themselves in a precarious position, teetering on the edge of these risks due to compromised platelet functionality and systemic disturbances within their coagulation frameworks. The management of such patients necessitates a meticulous approach to dosing adjustments and vigilant monitoring to navigate the perilous waters of anticoagulant therapy. This is especially critical considering the altered pharmacokinetics in CKD, where the clearance of drugs is significantly impeded, heightening the risk of accumulation and adverse effects. In the evolving narrative of anticoagulation therapy, the introduction of direct oral anticoagulants (DOACs) has heralded a new era, offering a glimmer of hope for those navigating the complexities of CKD. These agents, with their promise of easier management and a reduced need for monitoring, have begun to reshape the contours of care, particularly for patients not yet on dialysis. However, this is not without its caveats. The application of DOACs in the context of advanced CKD remains a largely uncharted territory, necessitating a cautious exploration to unearth their true potential and limitations. Moreover, the advent of innovative strategies such as left atrial appendage occlusion (LAAO) underscores the dynamic nature of anticoagulation therapy, potentially offering a tailored solution for those at the intersection of CKD and elevated stroke risk. Yet the journey toward integrating such advancements into standard practice is laden with unanswered questions, demanding rigorous investigation to illuminate their efficacy and safety across the spectrum of kidney disease. In summary, the management of anticoagulation in CKD is a delicate dance, requiring a harmonious blend of precision, caution, and innovation. As we venture further into this complex domain, we must build upon our current understanding, embracing both emerging therapies and the need for ongoing research. Only then can we hope to offer our patients a path that navigates the narrow strait between bleeding and clotting, toward safer and more effective care.

Platelets, inflammation, and purinergic receptors in chronic kidney disease

Platelets are anucleated cells that circulate in the bloodstream. Historically, platelets were thought to perform a singular function-stop bleeding via clotting. Although platelets do play a key role in hemostasis and thrombosis, recent studies indicate that platelets also modulate inflammation, and this platelet-induced inflammation contributes to the pathophysiology of various diseases such as atherosclerosis and diabetes mellitus. Thus, in recent years, our understanding of platelet function has broadened. In this review, we revisit the classic role of platelets in hemostasis and thrombosis and describe the newly recognized function of platelets in modulating inflammation. We cover the potential use of purinergic receptor antagonists to prevent platelet-modulated inflammation, particularly in patients with chronic kidney disease, and finally, we define key questions that must be addressed to understand how platelet-modulated inflammation contributes to the pathophysiology of chronic kidney disease.

Review on Kidney-Liver Crosstalk: Pathophysiology of Their Disorders

Kidney-liver crosstalk plays a crucial role in normal and certain pathological conditions. In pathologic states, both renal-induced liver damage and liver-induced kidney diseases may happen through these kidney-liver interactions. This bidirectional crosstalk takes place through the systemic conditions that mutually influence both the liver and kidneys. Ischemia and reperfusion, cytokine release and pro-inflammatory signaling pathways, metabolic acidosis, oxidative stress, and altered enzyme activity and metabolic pathways establish the base of this interaction between the kidneys and liver. In these concomitant kidney-liver diseases, the survival rates strongly correlate with early intervention and treatment of organ dysfunction. Proper care of a nephrologist and hepatologist and the identification of pathological conditions using biomarkers at early stages are necessary to prevent the complications induced by this complex and potentially vicious cycle. Therefore, understanding the characteristics of this crosstalk is essential for better management. In this review, we discussed the available literature concerning the detrimental effects of kidney failure on liver functions and liver-induced kidney diseases.

Ticagrelor or Clopidogrel as Antiplatelet Agents in Patients with Chronic Kidney Disease and Cardiovascular Disease: A Meta-analysis

INTRODUCTION

The worldwide prevalence of chronic kidney disease (CKD) has significantly increased in the past decades. Scientific reports have shown CKD to be an enhancing risk factor for the development of cardiovascular disease (CVD), which is the leading cause of premature death in patients with CKD. Clinical practice guidelines are ambiguous in view of the use of antiplatelet drugs in patients with CKD because patients with moderate-to-severe CKD were often excluded from clinical trials evaluating the efficacy and safety of anticoagulants and antiplatelet agents. In this analysis, we aimed to systematically assess the adverse cardiovascular and bleeding outcomes that were observed with ticagrelor versus clopidogrel use in patients with CKD and cardiovascular disease.

METHODS

Electronic databases including Web of Science, Google Scholar, http://www.

CLINICALTRIALS

gov , Cochrane database, EMBASE, and MEDLINE were carefully searched for English-based articles comparing ticagrelor with clopidogrel in patients with CKD. Adverse cardiovascular outcomes and bleeding events were the endpoints in this study. The latest version of the RevMan software (version 5.4) was used to analyze the data. Risk ratios (RR) with 95% confidence intervals (CI) were used to represent the data post analysis.

RESULTS

A total of 15,664 participants were included in this analysis, whereby 2456 CKD participants were assigned to ticagrelor and 13,208 CKD participants were assigned to clopidogrel. Our current analysis showed that major adverse cardiac events (MACEs) (RR: 0.85, 95% CI: 0.71-1.03; P = 0.09), all-cause mortality (RR: 0.82, 95% CI: 0.57- 1.18; P = 0.29), cardiovascular death (RR: 0.83, 95% CI: 0.56-1.23; P = 0.35), myocardial infarction (RR: 0.87, 95% CI: 0.70-1.07; P = 0.19), ischemic stroke (RR: 0.80, 95% CI: 0.58-1.11; P = 0.18), and hemorrhagic stroke (RR: 1.06, 95% CI: 0.38-2.99; P = 0.91) were not significantly different in CKD patients who were treated with ticagrelor versus clopidogrel. Thrombolysis in myocardial infarction (TIMI)-defined minor (RR: 0.89, 95% CI: 0.52-1.53; P = 0.68) and TIMI major bleeding (RR: 1.10, 95% CI: 0.69-1.76; P = 0.67) were also not significantly different. However, bleeding defined according to the academic research consortium (BARC) bleeding type 1 or 2 (RR: 1.95, 95% CI: 1.13-3.37; P = 0.02) and BARC bleeding type 3 or 5 (RR: 1.70, 95% CI: 1.17-2.48; P = 0.006) were significantly higher with ticagrelor.

CONCLUSIONS

When compared with clopidogrel, even though ticagrelor was not associated with higher risk of adverse cardiovascular outcomes in these patients with CKD, it was associated with significantly higher BARC bleeding. Therefore, the safety outcomes of ticagrelor still require further evaluation in patients with CKD. Nevertheless, this hypothesis should only be confirmed with more powerful results that could usually only be achieved using large-scale randomized trials.

The therapeutic potential of sphingolipids for cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide and Inflammation plays a critical role in the development of CVD. Despite considerable progress in understanding the underlying mechanisms and various treatment options available, significant gaps in therapy necessitate the identification of novel therapeutic targets. Sphingolipids are a family of lipids that have gained attention in recent years as important players in CVDs and the inflammatory processes that underlie their development. As preclinical studies have shown that targeting sphingolipids can modulate inflammation and ameliorate CVDs, targeting sphingolipids has emerged as a promising therapeutic strategy. This review discusses the current understanding of sphingolipids' involvement in inflammation and cardiovascular diseases, the existing therapeutic approaches and gaps in therapy, and explores the potential of sphingolipids-based drugs as a future avenue for CVD treatment.

The relationship between platelet distribution width and new-onset cardiovascular disease events in patients with peritoneal dialysis

Objectives

The global mortality rate from chronic kidney disease (CKD) has increased over the past two decades. Typically, peritoneal dialysis (PD) remains a useful alternative treatment for end-stage renal disease. Cardiovascular disease (CVD) is the main complication in PD patients. In terms of prognosis, it is reported that platelet distribution width (PDW) can predict adverse CVD events. However, the relationship between PDW and new-onset CVD in PD patients is not clear. This study aimed to explore the relationship between PDW and new-onset CVD in PD patients.

Methods

This was a retrospective cohort study, from 4 July 2005 to 31 December 2019, and a total of 1557 patients were recruited. PDW was respectively categorized into two groups: PDW ≤13.2 fL and PDW >13.2 fL. The primary outcome was a new-onset CVD event. Cox proportional hazards models were performed to assess the hazard ratio (HR). Receiver-operating characteristic (ROC) curves were applied to evaluate the predictive accuracy of the PDW on CVD events.

Results

During follow-up, 114 new-onset CVD events were recorded. Cox proportional hazards models showed a higher risk of CVD events in patients with high PDW (HR = 1.862 95%CI 1.205–2.877, p = 0.005). Kaplan–Meier cumulative incidence curves showed the risk of the first occurrence of CVD events was greater in the high PDW group (p = 0.006).

Conclusions

High PDW is associated with new-onset cardiovascular disease events in PD patients.

Platelet-Dependent Inflammatory Dysregulation in Patients with Stages 4 or 5 Chronic Kidney Disease: A Mechanistic Clinical Study

Background

Chronic kidney disease (CKD) is characterized by dysregulated inflammation that worsens with CKD severity. The role of platelets in modulating inflammation in stage 4 or 5 CKD remains unexplored. We investigated whether there are changes in platelet-derived thromboinflammatory markers in CKD with dual antiplatelet therapy (DAPT; aspirin 81 mg/d plus P2Y12 inhibitor).

Methods

In a mechanistic clinical trial, we compared platelet activation markers (aggregation and surface receptor expression), circulating platelet-leukocyte aggregates, leukocyte composition (monocyte subtypes and CD11b surface expression), and plasma cytokine profile (45 analytes) of non-CKD controls (n=26) and CKD outpatients (n=48) with a glomerular filtration rate (GFR) <30 ml/min per 1.73 m² on 2 weeks of DAPT.

Results

Patients with CKD demonstrated a reduced mean platelet count, elevated mean platelet volume, reduced platelet-leukocyte aggregates, reduced platelet-bound monocytes, higher total non-classic monocytes in the circulation, and higher levels of IL-1RA, VEGF, and fractalkine (all P<0.05). There were no differences in platelet activation markers between CKD and controls. Although DAPT reduced platelet aggregation in both groups, it had multifaceted effects on thromboinflammatory markers in CKD, including a reduction in PDGF levels in all CKD individuals, reductions in IL-1β and TNF-α levels in select CKD individuals, and no change in a number of other cytokines. Significant positive correlations existed for baseline IL-1β, PDGF, and TNF-α levels with older age, and for baseline TNF-α levels with presence of diabetes mellitus and worse albuminuria. Mean change in IL-1β and PDGF levels on DAPT positively correlated with younger age, mean change in TNF-α levels with higher GFR, and mean changes in PDGF, and TRAIL levels correlated with worse albuminuria. Minimum spanning trees plot of cytokines showed platelet-derived CD40L had a large reduction in weight factor after DAPT in CKD. Additionally, platelet-derived IL-1β and PDGF were tightly correlated with other cytokines, with IL-1β as the hub cytokine.

Conclusions

Attenuated interactions between platelets and leukocytes in the CKD state coincided with no change in platelet activation status, an altered differentiation state of monocytes, and heightened inflammatory markers. Platelet-derived cytokines were one of the central cytokines in patients with CKD that were tightly correlated with others. DAPT had multifaceted effects on thromboinflammation, suggesting that there is platelet-dependent and -independent inflammation in stage 4 or 5 CKD.

Effect of aspirin on primary prevention of cardiovascular disease and mortality among patients with chronic kidney disease

Chronic kidney disease is associated with an increased risk for cardiovascular and bleeding events. Data regarding the effectiveness and risks of aspirin therapy for primary prevention in the high-risk group of patients with chronic kidney disease are scant and controversial. This retrospective study included patients with chronic kidney disease. Participants were divided according to aspirin use. Outcomes included non-fatal cardiovascular events, major bleeding events and all-cause mortality. Among 10,303 patients, 2169 met the inclusion criteria and 1818 were included after 1:1 propensity-score matching. Our final cohort included patients with mean age of 73.4 ± 11.6 years, estimated glomerular filtration rate of 31.5 ± 10.5 ml/min/1.73m² with follow up of 4.9 ± 1.5 years. There were no significant differences in all-cause mortality and bleeding events (odds ratio = 1.03, confidence interval [0.62, 1.84], p = .58 and odds ratio = 1.09, confidence interval [0.65, 1.72], p = .87 respectively). The incidence of cardiovascular events was higher in aspirin users versus non-users on univariate analysis (p < 0.01) and was comparable after controlling for possible risk-factors (OR = 1.05, CI [0.61, 3.14], p = .85). Chronic aspirin use for primary prevention of cardiovascular disease was not associated with lower mortality, cardiovascular events or increased bleeding among patients with chronic kidney disease. Those results were unexpected and should prompt further research in this field.

Coronary Artery Disease in Chronic Kidney Disease: Need for a Heart-Kidney Team-Based Approach

Chronic kidney disease and coronary artery disease are co-prevalent conditions with unique epidemiological and pathophysiological features, that culminate in high rates of major adverse cardiovascular outcomes, including all-cause mortality. This review outlines a summary of the literature, and nuances pertaining to non-invasive risk assessment of this population, medical management options for coronary heart disease and coronary revascularisation. A collaborative heart-kidney team-based approach is imperative for critical management decisions for this patient population, especially coronary revascularisation; this review outlines specific periprocedural considerations pertaining to coronary revascularisation, and provides a proposed algorithm for approaching revascularisation choices in patients with end-stage kidney disease based on available literature.

Role of Platelets in Chronic Kidney Disease

Platelet-dependent mechanisms for excessive clotting and bleeding in CKD remain undefined. Moreover, platelets' contribution to inflammation, and specifically to CKD, are equally elusive. To date, descriptions of changes in the functional properties of circulating platelets during CKD have provided confusing interpretations. Experimental approaches that can advance our understanding of platelet dysfunction in CKD are needed, and studies that provide mechanistic insights into the dynamic relationships between thrombosis, bleeding, and inflammation associated with CKD will be essential to improve clinical management and outcomes for this vulnerable population. This article summarizes existing literature characterizing platelets in CKD and identifies areas that need further investigation.

Anemia-Induced Bleeding in Patients with Platelet Disorders

Anemia is not only a consequence of bleeding, but also a modifiable risk factor for bleeding in patients with thrombocytopenia or platelet function defects. In this review we outline the mechanism of anemia-induced bleeding in patients with platelet disorders, which involves a disturbance in normal red blood cell (RBC) rheology and reduced platelet margination to the endothelial surface due to a decrease in RBC mass, leading to impaired primary hemostasis and bleeding. Biologically, anemia reduces the mass of RBCs in the central column of flowing blood through a vessel resulting in fewer platelets coming into contact with the endothelial surface at the periphery of the flowing blood column. Thus, anemia results in impaired primary hemostasis. Von Willebrand factor (vWF) is another component of primary hemostasis and vWF deficiency, especially a deficiency of the highest vWF multimers, can also manifest with bleeding when concomitant anemia occurs. Clinically, patients at greatest risk for anemia-induced bleeding include patients with hematological malignancies in whom anemia and thrombocytopenia occur as a result of the underlying disease or the myelotoxic effects of treatment; patients with renal insufficiency with uremic thrombocytopathy and hypoproliferative anemia; and patients with inherited or acquired bleeding disorders affecting primary hemostasis (eg, Bernard-Soulier syndrome, von Willebrand disease) with chronic blood loss and iron deficiency anemia. Underlying abnormalities of any components of primary hemostasis plus concomitant anemia may result in major bleeding disorders; therefore, correction of remediable abnormalities-most notably, correction of the anemia- would be expected to have important clinical benefit. In this review we discuss how the correction of the anemia may lead to improvement of bleeding outcomes in patients with a primary hemostatic defect, supported by evidence from animal models, clinical trials and clinical experience.

Prescription Patterns in Dialysis Patients: Differences Between Hemodialysis and Peritoneal Dialysis Patients and Opportunities for Deprescription

Background:

Patients treated with maintenance dialysis are at high risk of polypharmacy given their many comorbidities as well as complications from their disease state and treatment. The prescribing patterns and burden of polypharmacy in patients treated with maintenance dialysis, and specifically the difference between hemodialysis (HD) and peritoneal dialysis (PD) prescribing, are not well characterized.

Objectives:

The objectives of this study were to review the prescribing patterns for patients treated with maintenance dialysis, to compare prescribing pattern between HD and PD, and to identify opportunities for deprescription.

Design:

This is a retrospective cohort study.

Setting:

This study was conducted in all dialysis centers in British Columbia, Canada.

Patients:

Patients who were receiving chronic dialysis (>120 days on the same dialysis modality) between June 3 and October 1, 2015, and registered in the British Columbia (BC) Renal Patient Records and Outcomes Management Information System.

Measurements:

Patient demographics as well as both prescription and non-prescription medications were collected. Comparison of discrete and continuous variables was made by chi-square analysis and independent t test, respectively. All statistical tests were 2-sided, and a P value of <.05 was considered statistically significant.

Methods:

Medications were classified by indication: (1) management of renal complications, (2) cardiovascular (CV) medications, (3) diabetes medications, or (4) management of symptoms, and then classified as to whether they were a “potentially inappropriate medication” (PIM) or not. Ethics approval was granted from the University of British Columbia Research and Ethics Board.

Results:

In total, 3017 patients met inclusion criteria (2243 HD, 774 PD). The mean age was 66.2 ± 14.8 years. The HD group had more patients over 80 years old (22.1% vs 12.5%) and more patients with diabetes and CV disease. The mean number (standard deviation [SD]) of discrete prescribed medications was 17.71 (5.72) overall with more medications in the HD group versus the PD group. The mean number of medications increased with dialysis vintage in both groups. HD patients were on more medications for renal complications and management of symptoms than PD patients. Of the total number of medications prescribed, 5.02 (2.78) were classified as a PIM, with the number of PIMs higher in HD vs PD patients: 5.37 (2.83) versus 4.02 (2.37).

Limitations:

In BC, some of the medications are prescribed through standardized protocols and may not be comparable with other Canadian provinces. We report here prescribing patterns, not utilization patterns, as we are not able to ascertain actual consumption of prescribed medication.

Conclusion:

This study reviews and characterizes both the prescription and non-prescription medication prescribed to HD patients and PD patients in BC. Pill burden in both groups is high, as is the prescription of PIMs. Patients receiving maintenance HD receive more overall medications and more PIMs. These results highlight areas of opportunities for future systematic and patient-informed deprescription initiatives in both patient groups.

Assessment of Thrombotic and Bleeding Tendency in Two Mouse Models of Chronic Kidney Disease: Adenine-Diet and 5/6th Nephrectomy

The coexistence of bleeding and thrombosis in patients with chronic kidney disease (CKD) is frequent and poorly understood. Mouse models are essential to understand complications of CKD and to develop new therapeutic approaches improving the health of patients. We evaluated the hemostasis in two models of renal insufficiency: adenine-diet and 5/6th nephrectomy (5/6Nx). Compared with 5/6Nx mice, mice fed with 0.25% adenine had more severe renal insufficiency and so higher levels of prothrombotic uremic toxins like indoxyl sulfate. More severe renal inflammation and fibrosis were observed in the adenine group, as demonstrated by histological and reverse transcription quantitative polymerase chain reaction experiments. Liver fibrinogen γ chain expression and level of plasma fibrinogen were increased only in adenine mice. In both CKD mouse models, tissue factor (TF) expression was increased in kidney and aorta extracts. Immunochemistry analysis of kidney sections showed that TF is localized in the vascular walls. Thrombin–antithrombin complexes were significantly increased in plasma from both adenine and 5/6Nx mice. Tail bleeding time increased significantly only in adenine mice, whereas platelet count was not significant altered. Finally, results obtained by intravital microscopy after laser-induced endothelial injury showed impaired platelet function in adenine mice and an increase in fibrin generation in 5/6Nx mice. To summarize, adenine diet causes a more severe renal insufficiency compared with 5/6Nx. The TF upregulation and the hypercoagulable state were observed in both CKD models. Bleeding tendency was observed only in the adenine model of CKD that recapitulates the whole spectrum of hemostasis abnormalities observed in advanced human CKD.

Role of direct oral anticoagulants in patients with kidney disease

The anticoagulation field is experiencing a renaissance that began with regulatory approval of the direct thrombin inhibitor dabigatran, a direct oral anticoagulant (DOAC), in 2010. The DOAC medication class has rapidly evolved to include the additional approval of 4 direct factor Xa inhibitors. Commensurately, DOAC use has increased and collectively account for the majority of new anticoagulant prescriptions. Despite exclusion of patients with moderate-to-severe kidney disease from most pivotal DOAC trials, DOACs are increasingly used in this setting. An advantage of DOACs is similar or improved antithrombotic efficacy with less bleeding risk when compared with traditional agents. Several post hoc analyses, retrospective studies, claims data studies, and meta-analyses suggest that these benefits extend to patients with kidney disease. However, the lack of randomized controlled trial data in specific kidney disease settings, with their unique pathophysiology, should be a call to action for the kidney community to systematically study these agents, especially because early data suggest that DOACs may pose less risk of anticoagulant-related nephropathy than do vitamin K antagonists. Most DOACs are renally cleared and are significantly protein bound in circulation; thus, the pharmacokinetics of these drugs are influenced by reduced renal function and proteinuria. DOACs are susceptible to altered metabolism by P-glycoprotein inhibitors and inducers, including drugs commonly used for the management of kidney disease comorbidities. We summarize the currently available literature on DOAC use in kidney disease and illustrate knowledge gaps that represent important opportunities for prospective investigation.

Emerging Factors Implicated in Fibrotic Organ-Associated Thrombosis: The Case of Two Organs

Thrombosis is at the heart of cardiovascular complications observed in specific diseases. A heightened thrombosis risk above that in general population in diseases such as myelofibrosis and chronic kidney disease implicates disease-specific mediators of thrombosis. This relative lack of information regarding the mechanisms of thrombosis in specific organ pathologies hitherto has remained limited. Evolving literature implicates some soluble factors in the blood of patients with discrete disorders, inflicting fundamental changes in the components of thrombosis. In this era of precision medicine, integrating these disease-specific factors in a comprehensive thrombotic risk assessment of patients is imperative in guiding therapeutic decisions. A complex network of mechanisms regulates each organ pathology and resultant thrombotic phenotypes. This review surveys different effectors of thrombogenicity associated with two pathologically fibrotic organs used as model systems, the bone marrow and kidney, as well as focuses attention to a common inducer of fibrosis and thrombosis, lysyl oxidase.

Twist drill craniostomy for traumatic acute subdural hematoma in the elderly: case series and literature review

Background

A large craniotomy is usually the first choice for removal of traumatic acute subdural hematoma (TASDH). To date, few studies have reported that TASDH could be successfully treated by twist drill craniostomy (TDC) alone or combined with instillation of urokinase. We aimed to define the TDC for the elderly with TASDH and performed literature review.

Case presentation

A total of 7 TASDH patients, who were presented and treated by TDC in this retrospective study between January 2009 and May 2017, consisted of 5 men and 2 women, ranging in age from 65 to 89 (average, 78.9) years. The patients’ baseline characteristics, including age, sex, medical history, received ventriculoperitoneal shunt for hydrocephalus or not, reason for avoiding or refusing large craniotomy, preoperative Glasgow Coma Scale (GCS), suffered from cerebral herniation or not, the location of TASDH, imaging characteristics of TASDH in CT scan, injury/surgery time interval, midline shift, preoperative neurologic deficit, operation time, and infusions of urokinase or not, were collected. The postoperative GCS, postoperative neurologic deficit, rebleeding or not, intracranial infection, and modified Rankin Scale (mRS) at 6 months after surgery were analyzed to access the safety and efficacy of evacuation with TDC. The results showed that the mean time interval from injury to TDC was 68.6 min (30–120 min). The mean distance of midline shift was 14.6 mm (10–20 mm). The preoperative GCS in all patients ranged from 4 to 13(median, 9). The mean duration of the operation was 14.4 min (6–19 min). Postoperative CT scan showed that hematoma evacuation rate was more than 70% in all cases. There were no cases of acute rebleeding and intracranial infection after TDC. No cases presented with chronic SDH at the ipsilateral side within 6 months after being treated by TDC alone or combined with instillation of urokinase. Favorable outcomes were shown in all cases (mRS scores 0–2) at 6 months after surgery.

Conclusions

TASDH in the elderly could be safely and effectively treated by TDC alone or combined with instillation of urokinase, which was a possible alternative for the elderly.

Management of Traditional Cardiovascular Risk Factors in CKD: What Are the Data?

Patients with non-dialysis-dependent chronic kidney disease (NDD-CKD) are 10 times more likely to die of cardiovascular (CV) diseases than the general population, and dialysis-dependent patients are at even higher risk. Although traditional CV risk factors are highly prevalent in individuals with CKD, these patients were often excluded from studies targeting modification of these risks. Although treatment of hypertension is beneficial in CKD, the best target blood pressure has not been established. Trial data showed that renin-angiotensin-aldosterone blockade may prevent CV events in patients with CKD. The risks of aspirin may equal the benefits in NDD-CKD samples, and there are no trials testing aspirin in dialysis-dependent patients. Lipid-lowering therapy improves CV outcomes in NDD-CKD, but not in dialysis-dependent patients. Strict glycemic control prevents CV events in nonalbuminuric individuals, but showed no benefit in those with baseline albuminuria with albumin excretion > 300mg/g, and there are no data in dialysis-dependent patients. Data for lifestyle modifications, such as weight loss, physical activity, and smoking cessation, are mostly observational and extrapolated from non-CKD samples. This comprehensive review summarizes the best existing evidence and current clinical guidelines for modification of traditional risk factors for the prevention of CV events in patients with CKD and identifies knowledge gaps.

Platelet reactivity in stable cardiovascular patients with chronic kidney disease

The study aimed to evaluate antiplatelet drug responsiveness in stable outpatients with cardiovascular disease and chronic kidney disease (CKD) and examine whether impaired antiplatelet drug responsiveness is associated with worse clinical outcomes in this population. Stable cardiovascular patients (n = 771) were enrolled at least one month after an acute ischemic atherothrombotic event. Antiplatelet drug responsiveness was assessed with specific assays (serum TxA₂ for aspirin, the VASP assay for clopidogrel) and other aggregation-based assays using different agonists. All patients were followed until the first occurrence of a major adverse cardiovascular event. The 133 CKD patients were found to have higher activity of von Willebrand factor and higher fibrinogen levels. After a median follow-up of 33 months, 88 events occurred in patients without CKD and 31 events in patients with CKD (5.0 events and 8.7 events per 100 patient years, respectively, HR = 1.75 (95% CI 1.16-2.63; p = 0.008). The prevalence of poor aspirin and clopidogrel responsiveness and high platelet reactivity as assessed with different aggregation-based assays was similar in patients with estimated GFR ≥ 60 ml/min, 45-59 ml/min, and < 45 ml/min. No significant interaction for CKD vs. non-CKD was observed for events occurrence in patients with or without high platelet reactivity on several assays, with the exception of collagen-induced aggregation. In stable cardiovascular patients, CKD is not associated with higher platelet reactivity. Decreased antiplatelet drug responsiveness is not associated with worse clinical outcomes in CKD patients.

Oral antiplatelet drugs in patients with chronic kidney disease (CKD): a review

Oral Antiplatelet Drugs (OAD) have a proven track record in the risk reduction of major cardiovascular events in patients with cardiovascular disease and normal kidney function. However, major gaps exist in our understanding of their effects on thrombosis and bleeding in chronic kidney disease (CKD). Clinical practice guidelines are ambiguous about use of such drugs in CKD patients, because patients with moderate to severe CKD were systematically excluded from clinical trials evaluating the efficacy and safety of OAD. Paradoxically, CKD patients are at high risk of thrombosis and major bleeding events. Thus, choosing the right combination of OAD for cardiovascular protection in these patients is challenging. Patients with CKD exhibit high rates of OAD hyporesponsiveness. It is, therefore, imperative to explore the mechanisms responsible for poor response to OAD in CKD patients in order to use these drugs more safely and effectively. This review explores suggested mechanisms of platelet dysfucntion in CKD patients and the available evidence on the efficacy and safety of oral antiplatelet drugs in patients with renal dysfunction.

Role of Cilostazol Therapy in Hemodialysis Patients with Asymptomatic Peripheral Arterial Disease: A Retrospective Cohort Study

Background. Peripheral arterial disease (PAD) and its relevant complications are more common in hemodialysis (HD) patients, while the evidence regarding antiplatelet therapy in CKD patients is scarce. We retrospectively analyzed the efficacy of cilostazol on outcomes in HD patients with asymptomatic PAD (aPAD). Methods. This cohort study enrolled 217 HD patients (median follow-up time: 5.75 years). Associations between cilostazol use and the outcomes were evaluated by time-dependent Cox regression analysis. Results. During follow-up, 39.5% (47/119) patients used cilostazol for aPAD and 31.8% (69/217) patients died. Cilostazol users had significantly lower CVD and all-cause mortalities (adjusted HR [95% CI]: 0.11 [0.03, 0.51] and 0.2 [0.08, 0.52]) than nonusers. Both death risks were nonsignificantly higher in cilostazol users than in HD patients without aPAD. The unadjusted and adjusted HR [95% CI] of CVD death risk were 0.4 [0.07, 2.12] and 0.14 [0.02, 0.8] for patients with aPAD during follow-up and were 0.74 [0.16, 3.36] and 0.19 [0.04, 0.93] for those with aPAD at initial. Conclusions. In HD patients with aPAD, lower CVD and all-cause mortality rates were observed in low-dose cilostazol user. Further evidences from large-scale prospective study and randomization trial are desired to confirm the effect of cilostazol.

Determinants of thromboxane biosynthesis in patients with moderate to severe chronic kidney disease

BACKGROUND

Mechanisms of accelerated atherothrombosis in patients with chronic kidney disease (CKD) are only partly characterized. The aims of this study were to evaluate the extent of thromboxane (TX)-dependent platelet activation in patients with CKD, and to characterize the determinants of altered TX biosynthesis in this setting, with particular reference to enhanced lipid peroxidation, low grade inflammation and CKD-related anemia.

PATIENTS AND METHODS

A cross sectional comparison between urinary 8-iso-PGF2α and 11-dehydro-TXB2, in vivo markers of oxidative stress and platelet activation, respectively, was performed in 115 patients with stage 1-4 CKD.

RESULTS

Levels of both urinary 11-dehydro-TXB2 and 8-iso-PGF2α increased sequentially across the four CKD stages (P<0.0001, Kruskal-Wallis test). Both urinary prostanoids were inversely associated with either estimated glomerular filtration rate (eGFR, P<0.0001) or hemoglobin levels (P<0.0001). A significant direct correlation was also observed between urinary 11-dehydro-TXB2 and 8-iso-PGF2α (Rho=0.620, P<0.0001). On multivariate analysis, urinary 8-iso-PGF2α (β=0.459, P<0.0001), hemoglobin levels (β=- 0.261, P=0.002) and eGFR (β=-0.172, P=0.032) were independent predictors of urinary 11-dehydro-TXB2 (adjusted R(2)=0.488).

CONCLUSIONS

This study provides biochemical evidence of persistent platelet activation in patients with CKD. This condition occurs early in the natural history of the disease and is related to kidney function and oxidative stress. Moreover, we found an independent inverse relationship between hemoglobin levels and TX-dependent platelet activation. This finding may provide a mechanistic link between CKD-related anemia and increased cardiovascular risk.

An oxidase road to platelet adhesion

Platelet adhesion to collagen via collagen receptors is an important part of thrombosis. In this issue of Blood, Matsuura et al identify collagen receptors as previously unrecognized targets of the extracellular enzyme lysyl oxidase (LOX), the level of which is increased in myeloproliferative neoplasms (MPNs) and other conditions associated with pathological thromboses.

Differences in Whole Blood Platelet Aggregation at Baseline and in Response to Aspirin and Aspirin Plus Clopidogrel in Patients With Versus Without Chronic Kidney Disease

Thrombotic events while receiving antiplatelet agents (APAs) are more common in subjects with versus without chronic kidney disease (CKD). Data on antiplatelet effects of APA in CKD are scarce and limited by lack of baseline platelet function before APA treatment. We hypothesized subjects with stages 4 to 5 CKD versus no CKD have greater baseline platelet aggregability and respond poorly to aspirin and clopidogrel. In a prospective controlled study, we measured whole blood platelet aggregation (WBPA) in 28 CKD and 16 non-CKD asymptomatic stable outpatients not on APA, frequency-matched for age, gender, obesity, and diabetes mellitus. WBPA was remeasured after 2 weeks of each aspirin and aspirin plus clopidogrel. The primary outcome was percent inhibition of platelet aggregation (IPA) from baseline. The secondary outcome was residual platelet aggregability (RPA; proportion with <50% IPA). Baseline platelet aggregability was similar between groups except adenosine diphosphate-induced WBPA, which was higher in CKD versus non-CKD; median (interquartile range) = 13.5 (9.5 to 16.0) versus 9.0 (6.0 to 12.0) Ω, p = 0.007. CKD versus non-CKD participants had lower clopidogrel-induced IPA, 38% versus 72%, p = 0.04. A greater proportion of CKD versus non-CKD participants had RPA after clopidogrel treatment (56% vs 8.3%, p = 0.01). There were no significant interactions between CKD and the presence of cytochrome P450 2C19 polymorphisms for platelet aggregability in clopidogrel-treated participants. In conclusion, CKD versus non-CKD subjects exhibited similar platelet aggregation at baseline, similar aspirin effects and greater RPA on clopidogrel, which was independent of cytochrome P450 2C19 polymorphisms.

Lysyl oxidase is associated with increased thrombosis and platelet reactivity

Lysyl oxidase (LOX) is overexpressed in various pathologies associated with thrombosis, such as arterial stenosis and myeloproliferative neoplasms (MPNs). LOX is elevated in the megakaryocytic lineage of mouse models of MPNs and in patients with MPNs. To gain insight into the role of LOX in thrombosis and platelet function without compounding the influences of other pathologies, transgenic mice expressing LOX in wild-type megakaryocytes and platelets (Pf4-Lox(tg/tg)) were generated. Pf4-Lox(tg/tg) mice had a normal number of platelets; however, time to vessel occlusion after endothelial injury was significantly shorter in Pf4-Lox(tg/tg) mice, indicating a higher propensity for thrombus formation in vivo. Exploring underlying mechanisms, we found that Pf4-Lox(tg/tg) platelets adhere better to collagen and have greater aggregation response to lower doses of collagen compared with controls. Platelet activation in response to the ligand for collagen receptor glycoprotein VI (cross-linked collagen-related peptide) was unaffected. However, the higher affinity of Pf4-Lox(tg/tg) platelets to the collagen sequence GFOGER implies that the collagen receptor integrin α2β1 is affected by LOX. Taken together, our findings demonstrate that LOX enhances platelet activation and thrombosis.

Clopidogrel, prasugrel, ticagrelor or vorapaxar in patients with renal impairment: do we have a winner?

The optimal utilization of antiplatelet therapy in patients with renal impairment (RI) following acute coronary syndromes (ACS) represents an urgent, unmet and yet unsolved need with regards to the choice of agents, duration of treatment and potential dose/regimen adjustment. The lack of any large randomized trials designed and powered specifically in such high-risk patients, absence of the uniformed efficacy and safety data reporting policy to the FDA and endless overoptimistic publications based on post hoc analyses of primary trials sometimes exaggerating benefits and hiding risks, clouds reality. In addition, triaging RI patients is problematic due to ongoing kidney deterioration and the fact that such patients are prone to both vascular occlusions and bleeding. The authors summarize available FDA-confirmed evidence from the latest trials with approved antiplatelet agents, namely clopidogrel (CAPRIE, CURE, CREDO, CLARITY, CHARISMA); prasugrel (TRITON, TRILOGY); ticagrelor (PLATO, and PEGASUS); and vorapaxar (TRACER and TRA2P) in RI patient cohorts on top of aspirin as part of dual antiplatelet therapy (DAPT). We deliberately avoided any results unless they were verified by the FDA, with the exception of the recent PEGASUS, since Agency reviews are not yet available. Despite differences among the trials and DAPT choices, RI patients universally experience much higher (HR = 1.3-3.1) rates of primary endpoint events, and bleeding risks (HR = 1.7-3.6). However, only ticagrelor increases creatinine and uric acid levels above that of clopidogrel; has the worst incidence of serious adverse events, more adverse events, and inferior outcomes in patients with severe (eGFR <30 ml/min), especially in the lowest (eGFR <15 ml/min) RI subsets. Clopidogrel, prasugrel and vorapaxar appear safer. Moreover, less aggressive half dose (5 mg/daily) prasugrel and strict DAPT, are well justified in RI, but not predominantly triple strategies with vorapaxar as tested in TRA2P and especially in TRACER. In conclusion, data from clinical trials, their sub-studies and affiliated FDA reviews indicate that RI cause more vascular occlusions and bleeding in ACS patients treated with DAPT. Among the novel antiplatelet agents, prasugrel and vorapaxar, but probably not ticagrelor, offer advantage in RI patients.