Antiplatelet therapy for patients with diabetes mellitus and acute coronary syndrome

Impact of Diabetes on Platelet Function in Acute Ischemic Stroke Patients Taking Dual Antiplatelet Therapy

Objectives: Diabetes mellitus (DM) is a significant risk factor for ischemic stroke and associated with platelet reactivity. We aim to evaluate the effect of DM on platelet function in acute ischemic stroke patients taking dual antiplatelet therapy (DAPT).

Methods: We consecutively included patients with acute ischemic stroke taking DAPT. Platelet function was assessed by thromboelastography and the arachidonic acid (AA) or adenosine diphosphate (ADP) induced platelet inhibition rate were used to confirmed the high-residual on-treatment platelet reactivity (HRPR) to aspirin or clopidogrel. We classified patients into DM and non-DM groups. The association between DM and platelet function was assessed and the confounding factors were adjusted by propensity score matching (PSM) analysis. The independent risk factors of HRPR were determined by multivariate logistic regression analysis.

Results: A total of 1,071 acute ischemic stroke patients, 712 in the non-DM group and 359 in the DM group, were included. Patients with DM had a significantly higher maximum amplitude (63.0 vs. 62.0 mm, P < 0.01), ADP-induced clot strength (34.6 vs. 30.3 mm, P < 0.01) and clopidogrel HRPR rate (22.6% vs. 17.3%, P = 0.038) than those without DM. Among 662 patients after PSM, the maximum amplitude (63.1 vs. 62.5 mm, P = 0.032), ADP-induced clot strength (34.6 vs. 29.3 mm, P < 0.01) and clopidogrel HRPR rate (23.0% vs. 15.7%, P = 0.018) is still higher in the DM group. DM was an independent factor of clopidogrel HRPR (OR = 1.48, 95% CI: 1.03–2.07, P < 0.05).

Conclusions: In acute ischemic stroke patients taking DAPT, DM is associated with increased platelet reactivity and higher prevalence of clopidogrel HRPR.

Systematic review and meta-analysis of optimal P2Y12 blockade in dual antiplatelet therapy for patients with diabetes with acute coronary syndrome

Background

Patients with diabetes are at increased risk of acute coronary syndromes (ACS) and their mortality and morbidity outcomes are significantly worse following ACS events, independent of other comorbidities. This systematic review sought to establish the optimum management strategy with focus on P2Y₁₂ blockade in patients with diabetes with ACS.

Methods

MEDLINE (1946 to present) and EMBASE (1974 to present) databases, abstracts from major cardiology conferences and previously published systematic reviews were searched to June 2014. Relevant randomised control trials with clinical outcomes for P2Y₁₂ inhibitors in adult patients with diabetes with ACS were scrutinised independently by 2 authors with applicable data was extracted for primary composite end point of cardiovascular death, myocardial infarction (MI) and stroke; enabling calculation of relative risks with 95% CI with subsequent direct and indirect comparison.

Results

Four studies studied clopidogrel in patients with diabetes, with two (3122 patients) having primary outcome data showing superiority of clopidogrel against placebo with RR0.84 (95% CI 0.72–0.99). Irrespective of management strategy, the newer agents prasugrel (2 studies) and ticagrelor (1 study) had a lower primary event rate compared with clopidogrel; RR 0.80 (95% CI 0.66 to 0.97) and RR 0.89 (95% CI 0.77 to 1.02), respectively. When ticagrelor was indirectly compared with prasugrel, there was a trend to an improved primary outcome with prasugrel (RR 1.11 (95% CI 0.94 to 1.31)) particularly in those managed with percutaneous coronary intervention (PCI) (RR 1.23 (95% CI 0.95 to 1.59)). Prasugrel demonstrated a statistical superiority with prevention of further MI with RR 1.48 (95% CI 1.11 to 1.97). This was not at the expense of increased major thrombolysis in MI (TIMI) bleeding rates RR 0.94 (95% CI 0.59 to 1.51).

Conclusions

This meta-analysis shows the addition of a P2Y₁₂ inhibitor is superior to placebo, with a trend favouring the use of prasugrel in patients with diabetes with ACS, particularly those undergoing PCI.

Ticagrelor: positive, negative and misunderstood properties as a new antiplatelet agent

Dual antiplatelet therapy is essential for the management of acute coronary syndrome. In particular, combination therapy using aspirin with a platelet ADP (i.e. P2Y12 ) receptor inhibitor, such as clopidogrel, prasugrel or, more recently, ticagrelor, has been recommended for patients with acute coronary syndrome. Pharmacological agents that reversibly inhibit platelet aggregation without metabolic activation in the liver are believed to reduce cardiovascular mortality compared with the current drug of choice for antiplatelet therapy, namely clopidogrel. These findings are based on a multicentre, double-blind, double-dummy, randomized controlled trial. Numerous factors are postulated to contribute to the improved survival of patients who take ticagrelor compared with those taking clopidogrel, including the risk of myocardial infarction, heart failure, arrhythmia and bleeding. In addition, clopidogrel may lead to a much higher incidence of infection. Although ticagrelor has recently been approved for use in the US and exhibits superiority over other antiplatelet agents, certain concerns remain regarding its use, including lung injury and dyspnoea, thus raising the issue of its true superiority over clopidogrel or prasugrel. Recent studies into ticagrelor report conflicting data, with certain aspects of its mechanisms of action still not fully understood. Ticagrelor has beneficial effects following its clinical application, such as achieving overall higher reductions in mortality compared with the use of clopidogrel and prasugrel. Harmful effects associated with the use of ticagrelor include a higher incidence of dyspnoea and major bleeding compared with clopidogrel.

Randomized assessment of ticagrelor versus prasugrel antiplatelet effects in patients with diabetes

OBJECTIVE

It has been postulated that prasugrel might be the preferred treatment option in diabetes mellitus (DM) patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI). We aimed to compare the pharmacodynamic action of ticagrelor versus prasugrel.

RESEARCH DESIGN AND METHODS

In a prospective, single-center, single-blind, crossover study, 30 consecutive ACS patients with DM who had been pretreated with clopidogrel were randomized to either 90 mg ticagrelor twice daily or 10 mg prasugrel once daily with a 15-day treatment period. Platelet reactivity (PR) was assessed with the VerifyNow P2Y12 function assay, measured in P2Y12 reaction units (PRU).

RESULTS

PR was significantly lower after ticagrelor (45.2 PRU [95% CI 27.4-63.1]) compared with prasugrel (80.8 PRU [63.0-98.7]), with a least squares mean difference of -35.6 PRU (-55.2 to -15.9, P = 0.001). High PR rate was 0% for ticagrelor and 3.3% for prasugrel (P = 1.0).

CONCLUSIONS

In DM patients with ACS who had been pretreated with clopidogrel and who undergo PCI, ticagrelor achieves a significantly higher platelet inhibition than prasugrel. Both antiplatelet agents effectively treat high PR. The relevance of these findings to the clinical efficacy and safety of ticagrelor and prasugrel in DM patients needs further elucidation.