Effect of adjunctive dipyridamole to DAPT on platelet function profiles in stented patients with high platelet reactivity. The result of the ACCEL-DIP Study

Effectiveness and safety of high dose clopidogrel plus aspirin in ischemic stroke patients with the single CYP2C19 loss-of-function allele: a randomized trial

Background

Dual antiplatelet aggregation therapy leads to better outcomes in patients with carotid artery stenosis, intracranial artery stenosis, minor strokes, or transient ischaemic attacks. However, carriers of the CYP2C19 loss-of-function allele may not experience the desired effects. We attempted to increase the clopidogrel dose to determine whether it would improve the outcomes of stroke patients who carry a single loss-of-function allele.

Methods

We recruited 131 patients with minor ischaemic stroke, within less than 7 days of stroke onset and a CYP2C19 loss-of-function allele, who had moderate-to-severe cerebral artery stenosis. Patients were divided into the high dose group (clopidogrel 150 mg per day + aspirin 100 mg per day over 21 days.) and a normal dose group (clopidogrel 75 mg per day + aspirin 100 mg per day over 21 days). The reported outcomes included any vascular or major bleeding events as the primary and safety endpoints, respectively.

Results

One and six vascular events occurred in the high dose and normal dose groups during the 3-months follow-up period, respectively. However, no significant difference was found between the two groups when adjusted for history of diabetes (hazard ratio, 5482; 95% confidence interval, 0.660 to 45.543; P = 0.115). No major bleeding events occurred.

Conclusions

In patients with ischaemic stroke who had a single CYP2C19 loss-of-function allele and moderate to severe cerebral stenosis, fewer vascular events occurred within 3 months with high dose of clopidogrel and aspirin than with normal dose of clopidogrel and aspirin. However, the difference between the two groups was not significant.

Trial registration

Clinical study of clopidogrel in the treatment of patients with symptomatic moderate to severe cerebral artery stenosis with intermediate metabolites of CYP2C19, URL: http://www.chictr.org.cn/. Unique identifier: ChiCTR1800017411, 07/28/2018;

The Dipyridamole Added to Dual Antiplatelet Therapy in Cerebral Infarction After First Acute Myocardial Infarction: A Nationwide, Case-Control Study

Background and Purpose: No previous study has compared the impact of dipyridamole-based triple antiplatelet therapy on secondary stroke prevention and long-term outcomes to that of dual antiplatelet therapy (DAPT) in patients with acute myocardial infarction (AMI) and previous stroke. This study aimed to evaluate the impact of dipyridamole added to DAPT on stroke prevention and long-term outcomes in patients with cerebral infarction after first AMI.

Methods: This nationwide, case-control study included 75,789 patients with cerebral infarction after first AMI. A 1:4 propensity score matching ratio was adopted based on multiple variables. Finally, the data of 4,468 patients included in the DAPT group and 1,117 patients included in the Dipyridamole-DAPT group were analyzed. Primary outcome was overall survival. Secondary outcomes were cumulative event rate of recurrent MI or stroke, and cumulative intracerebral hemorrhage (ICH) and gastrointestinal bleeding rate.

Results: Long-term survival rate was comparable between the two groups (log-rank P = 0.1117), regardless of sex analyses. However, after first year, DAPT subgroup revealed better survival over DAPT-dipyridamole subgroup (log-rank P = 0.0188). In age subgroup analysis, a lower survival rate was detected in younger patients from the Dipyridamole-DAPT group after first year (log-rank P = 0.0151), but no survival difference for older patients. No benefit of Dipyridamole-DAPT was detected for patients after AMI, regardless of the myocardial infarction type. DAPT was superior to Dipyridamole-DAPT in patients who underwent percutaneous coronary intervention (PCI) (log-rank P = 0.0153) and ST elevation myocardial infarction after first year (log-rank P = 0.0019). Dipyridamole-DAPT did not reduce cumulative event rate of recurrent MI or stroke in patients after AMI. Moreover, Dipyridamole-DAPT increased the cumulative ICH rate (log-rank P = 0.0026), but did not affect the cumulative event rate of gastrointestinal bleeding. In Cox analysis, dipyridamole did not improve long-term survival.

Conclusions: This nationwide study showed that Dipyridamole-DAPT, compared with DAPT, did not improve long-term survival in patients with stroke after AMI, and was related to poor outcomes after 1 year. Dipyridamole-DAPT did not reduce recurrent rate of MI or stroke, but increased the ICH rate without impacting the incidence of gastrointestinal bleeding.

Anti-platelet drugs and their necessary interaction with endothelial mediators and platelet cyclic nucleotides for therapeutic efficacy

For many millions of patients at secondary risk of coronary thrombosis pharmaceutical protection is supplied by dual anti-platelet therapy. Despite substantial therapeutic developments over the last decade recurrent thrombotic events occur, highlighting the need for further optimisation of therapies. Importantly, but often ignored, anti-platelet drugs interact with cyclic nucleotide systems in platelets and these are the same systems that mediate key endogenous pathways of platelet regulation, notably those dependent upon the vascular endothelium. The aim of this review is to highlight interactions between the anti-platelet drugs, aspirin and P2Y₁₂ receptor antagonists and endogenous pathways of platelet regulation at the level of cyclic nucleotides. These considerations are key to concepts such as anti-platelet drug resistance and individualized anti-platelet therapy which cannot be understood by study of platelets in isolation from the circulatory environment. We also explore novel and emerging therapies that focus on preserving haemostasis and how the concepts outlined in this review could be exploited therapeutically to improve anti-thrombotic efficacy whilst reducing bleeding risk.

Current antiplatelet treatment strategy in patients with diabetes mellitus

Patients with diabetes mellitus (DM) have accelerated atherosclerosis with an increased risk for atherothrombotic cardiovascular complications. A state of high platelet reactivity and activation, hypercoagulability (prothrombotic state) and a subdued response to standard antiplatelet agents may explain high rate of adverse cardiovascular events in patients with DM. Several antithrombotic treatment strategies have been developed to control the prothrombotic state in patients with DM: dose modification of commonly used agents; use of potent agents; and addition of a third antithrombotic drug (triple therapy) to commonly prescribed dual antiplatelet therapy of aspirin and a P2Y12 inhibitor. The present review aims to provide an overview of the current knowledge on platelet abnormalities in patients with DM, focusing on the challenges and perspectives of antiplatelet treatment strategies in this population.