Current state-of-the-art antiplatelet and anticoagulation therapy in diabetic patients with coronary artery disease

Diabetes mellitus is a complex disease that leads to long-term damage to various organ systems. Among the numerous cardiovascular disease-related complications, thrombotic events frequently occur in patients with diabetes. Although guidelines exist for treating and preventing most diabetes-related co-morbidities, the evidence on antithrombotic therapy in primary and secondary prevention is limited due to the scarcity of randomized trials dedicated to patients with diabetes mellitus. Most of the available data are derived from studies that only included a small proportion of patients with diabetes. The present review provides an overview of the status of knowledge on antiplatelet and anticoagulation therapy in patients with diabetes, focusing on the risk-benefit balance of these therapies and future treatment strategies.

An updated drug profile of ticagrelor with considerations on the treatment of patients with coronary artery disease and diabetes mellitus

INTRODUCTION

Ticagrelor is an antiplatelet agent acting through direct and reversible competitive inhibition of the platelet P2Y₁₂ receptor. While the clinical merits of ticagrelor in patients who experienced an acute coronary syndrome are widely accepted, its role in stable coronary artery disease is less established. Recently, large-scale trials of ticagrelor have been published in this setting, including a trial in patients with diabetes mellitus (DM).

AREAS COVERED

This review aims to inform about recent findings on ticagrelor, by appraising the current body of evidence on its use in different clinical scenarios, particularly in DM, ranging from pharmacology to clinical outcomes and future directions.

EXPERT OPINION

The results of the THEMIS trial, conducted in DM patients with stable coronary artery disease and no prior stroke or myocardial infarction, showed that although ticagrelor in addition to aspirin reduced the risk of ischemic events, this was associated with a parallel increase in bleeding complications. However, patients with history of percutaneous coronary intervention seemed to benefit more from adjunctive ticagrelor therapy. Careful bleeding and ischemic risk stratification remains crucial to define the best antithrombotic strategy for the individual patient.

Benefits and Risks of Anticoagulation in Acute Coronary Syndrome

BACKGROUND

Both antiplatelets and anticoagulants are necessary in the management of acute coronary syndrome (ACS), although the exact proportion of antithrombotic effect that each drug and class should ideally provide remains a matter of ongoing study.

AREA OF UNCERTAINTY

Defining the best combination between the antiplatelet agents and oral anticoagulants (OACs) can be challenging. The choice is particularly important for special categories of patients with ACS who have an indication of a long-term OAC.

DATA SOURCES

A literature search regarding benefits and risks of anticoagulation in ACS was conducted through MEDLINE and EMBASE (past 20 years until September 2018).

THERAPEUTIC ADVANCES

Many patients with ACS have an indication for long-term OACs. Those receiving dual antiplatelet therapy and anticoagulants are considered to be at a high bleeding risk. The addition of a vitamin K antagonist (VKA) imposes a target international normalized ratio of 2.0-3.0. When non-VKA oral anticoagulants are used, the lowest effective tested dose for stroke prevention should be applied. For most patients, triple therapy in the form of an OAC plus dual antiplatelet therapy [aspirin and P2Y12 inhibitors (usually clopidogrel)] should be considered for 3-6 months. Later, dual therapy (OAC plus aspirin or clopidogrel) should be considered for an additional 6 months. After 1 year, it is recommended that only the OAC is maintained. In cases of very high bleeding risk, triple therapy can be reduced to 1 month after ACS, continuing on dual therapy up to 1 year, and thereafter only anticoagulation. In general, the bleeding risk seems to be lower with non-VKA oral anticoagulants than VKA plus antiplatelet combination.

CONCLUSIONS

Many risk factors for ischemic events and bleeding overlap. The clinician's challenges include monitoring patients' adherence and global assessment of the antithrombotic effect that incorporates antiplatelet and anticoagulant effects.

The prognostic value of multiple electrode aggregometry and light transmittance aggregometry in stable cardiovascular patients with type 2 diabetes mellitus

AIM

Limited data are available regarding the clinical relevance of platelet function measurements in stable patients with coronary artery disease (CAD). Our aim is to evaluate the agreement between multiple electrode aggregometry (MEA) and light transmittance aggregometry (LTA) in detecting clopidogrel low responders and their prognostic value in CAD patients with type 2 diabetes mellitus (T2DM) on dual platelet inhibition.

METHODS

LTA and MEA were performed in 122 stable cardiovascular patients with T2DM. The upper quartile of patients according to maximum LTA (LTAmax) and MEA measurements were defined as clopidogrel low responders. Agreement between the two methods was evaluated by kappa statistics. We assessed the potential correlation between antiplatelet response and clinical outcome and the optimal cutoff value according to ROC analysis to predict the occurrence of major adverse cardiovascular events (MACE), during 1-year follow-up period.

RESULTS

Cohen's kappa coefficients (0.214) indicated fair agreement (70.2%) between LTA and MEA. A total of 25 MACE occurred in 108 patients (23.1%). Patients with MACE had higher LTAmax than those without (57.1 ± 16.5 vs 49.3 ± 18.3, respectively, p = 0.023). MEA measurements were similar between patients with and without MACE (30.1 ± 15.4 vs 30.6 ± 20.8, respectively; p = 0.84). Multiple logistic regression showed LTAmax response as an independent predictor of death from cardiovascular causes (Odds Ratio, adjusted:0.2;0.05-0.81). ROC analysis indicated that LTAmax cutoff of 62.5% best predicted death (AUC = 0.67, sensitivity = 78%, specificity = 61.5%).

CONCLUSIONS

The assessment of platelet responsiveness remains highly test-specific. Our results support the prognostic role of LTA, but not MEA testing, for death risk evaluation in stable cardiovascular T2DM patients.

Thrombosis and Vascular Inflammation in Diabetes: Mechanisms and Potential Therapeutic Targets

Cardiovascular disease remains the main cause of morbidity and mortality in patients with diabetes. The risk of vascular ischemia is increased in this population and outcome following an event is inferior compared to individuals with normal glucose metabolism. The reasons for the adverse vascular profile in diabetes are related to a combination of more extensive atherosclerotic disease coupled with an enhanced thrombotic environment. Long-term measures to halt the accelerated atherosclerotic process in diabetes have only partially addressed vascular pathology, while long-term antithrombotic management remains largely similar to individuals without diabetes. We address in this review the pathophysiological mechanisms responsible for atherosclerosis with special emphasis on diabetes-related pathways. We also cover the enhanced thrombotic milieu, characterized by increased platelet activation, raised activity of procoagulant proteins together with compromised function of the fibrinolytic system. Potential new therapeutic targets to reduce the risk of atherothrombosis in diabetes are explored, including alternative use of existing therapies. Special emphasis is placed on diabetes-specific therapeutic targets that have the potential to reduce vascular risk while keeping an acceptable clinical side effect profile. It is now generally acknowledged that diabetes is not a single clinical entity but a continuum of various stages of the condition with each having a different vascular risk. Therefore, we propose that future therapies aiming to reduce vascular risk in diabetes require a stratified approach with each group having a "stage-specific" vascular management strategy. This "individualized care" in diabetes may prove to be essential to improve vascular outcome in this high risk population.

Comparison of pharmacodynamic effects of ticagrelor vs prasugrel in type 2 diabetes mellitus patients with coronary heart disease

WHAT IS KNOWN AND OBJECTIVE

Patients with type 2 diabetes mellitus (T2DM) are at higher risk of thrombotic complications. Studies have indicated that patients with T2DM have impaired clopidogrel-induced antiplatelet effect. Ticagrelor and prasugrel are two latest generation P2Y₁₂ inhibitors with advantageous platelet inhibitory profiles. However, the pharmacodynamic differences between the two drugs in patients with T2DM remain poorly explored.

METHODS

This study, involving 140 patients with T2DM following percutaneous coronary intervention (PCI), evaluated the efficacy of aspirin upon concomitant use of prasugrel (10 mg/d) or ticagrelor (90 mg/d). Platelet reactivity was assessed by value of ADP-induced light transmittance aggregometry (LTA) and vasodilator-stimulated phosphoprotein phosphorylation-platelet reactivity index (VASP-PRI) at baseline, 7 and 30 days after randomized P2Y₁₂ inhibitor treatment.

RESULTS

The study showed a decreased platelet reactivity after use of P2Y₁₂ inhibitors (both P < .001). On the basis of comparison between regimens, apart from the prasugrel group having a significantly higher LTA value at the 30-day time point (P = .043), there existed no significant differences in platelet reactivity at separate time points (all P > .05). As for intragroup measurements, when compared with 7-day and 30-day time points, similar platelet reactivity was documented in the ticagrelor group (both P > .05), but LTA tests showed a significant increase with time (days 7-30) in the prasugrel group (P = .050).

WHAT IS NEW AND CONCLUSION

Although ticagrelor and prasugrel have similar platelet inhibitory effects in patients with T2DM, if a P2Y₁₂ inhibitor is necessitated in patients with T2DM, ticagrelor might exert a more stable antiplatelet effect with 30-day short-term treatment.

Red cell distribution width as a significant indicator of medication and prognosis in type 2 diabetic patients

Whether red cell distribution width (RDW) can be a potential indicator for diabetic nephropathy (DN) is unknown. A total of 809 type 2 diabetes mellitus (T2D) patients were divided into 4 groups according to the quartiles (Q) of the RDW (%): Q1 ≤ 12.4 (n = 229), 12.4 < Q2 ≤ 12.9 (n = 202), 12.9 < Q3 < 13.5 (n = 168), Q4 ≥ 13.5 (n = 210). Results showed that the levels in Q4 group was higher in age, disease duration, systolic blood pressure, blood urea nitrogen, creatinine, uric acid and proteinuria but lower in hemoglobin, serum albumin and glycosylated hemoglobin compared to Q1 group. Furthermore, the incidences of DN, diabetic peripheral neuropathy, hypertension and coronary heart disease in the Q3 or Q4 group were higher compared to Q1 group. Medications including calcium channel blockers and antiplatelet therapy also showed higher frequencies in Q3 or Q4 group compared to Q1. Logistic regression indicated that the antiplatelet therapy (OR = 2.065), hypertension (OR = 2.819), creatinine (OR = 4.473) and proteinuria (OR = 2.085) were positively associated with level of Q4 group, but higher hemoglobin (OR = 0.021) and serum Ca²⁺ (OR = 0.178) were negatively associated with Q4. This data suggest that high level of RDW in T2D patients indicates a higher risk and a poor prognosis for DN.

Impact of Diabetes Mellitus on the Pharmacodynamic Effects of Ticagrelor Versus Clopidogrel in Troponin-Negative Acute Coronary Syndrome Patients Undergoing Ad Hoc Percutaneous Coronary Intervention

Background

Diabetes mellitus (DM) is associated with enhanced platelet reactivity and impaired response to oral antiplatelet therapy, including clopidogrel. This post hoc analysis investigated the pharmacodynamic effects of ticagrelor versus clopidogrel loading dose (LD) in troponin‐negative acute coronary syndrome patients with or without DM undergoing percutaneous coronary intervention in the Ad Hoc PCI study.

Methods and Results

Patients randomized (1:1) to receive ticagrelor 180 mg LD or clopidogrel 600 mg LD were assessed by diabetic status. Platelet reactivity (P2Y₁₂ reaction units [PRU] on VerifyNow^® assay) was measured pre‐LD, at 0.5, 2, and 8 hours post‐LD, and at the end of the percutaneous coronary intervention. The primary endpoint was PRU levels 2 hours post‐LD; secondary endpoints included rates of high on‐treatment platelet reactivity (PRU≥208). Of 100 randomized patients, 51 received ticagrelor (DM, n=20; non‐DM, n=31) and 49 clopidogrel (DM, n=16; non‐DM, n=33). At 2 hours post‐LD, mean (SD) PRU levels in DM patients were 130.1 (111.7) with ticagrelor versus 287.6 (71.9) with clopidogrel (mean [95%CI] difference −157.5 [−225.3, −89.8]; P<0.001); in non‐DM patients, they were 75.3 (75.7) versus 243.0 (72.4) (mean difference −167.7 [−207.1, −128.3]; P<0.001). High on‐treatment platelet reactivity rates at 2 hours post‐LD were also significantly (P<0.001) reduced with ticagrelor versus clopidogrel in DM and non‐DM patients. Between‐treatment differences for PRU and high on‐treatment platelet reactivity were not significant at earlier time points but were at 8 hours post‐LD (P<0.001).

Conclusions

Compared with clopidogrel, ticagrelor achieved faster, enhanced platelet inhibition and reduced high on‐treatment platelet reactivity rates, in DM and non‐DM patients.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01603082.