Developments in antiplatelet therapy for acute coronary syndromes and considerations for long-term management

The Molecular Aspects of Disturbed Platelet Activation through ADP/P2Y12 Pathway in Multiple Sclerosis

Epidemiological studies confirm a high risk of ischemic events in secondary-progressive multiple sclerosis (SP MS) patients, directly associated with an increased level of pro-thrombotic activity of platelets. Our work aimed to verify potential molecular abnormalities of the platelet P2Y₁₂ receptor expression and functionality as a cause of an increased risk of thromboembolism observed in the course of MS. We have demonstrated an enhanced platelet reactivity in response to adenosine diphosphate (ADP) in SP MS relative to controls. We have also shown an increased mRNA expression for the P2RY12 gene in both platelets and megakaryocytes, as well as enhanced density of these receptors on the platelet surface. We postulate that one of the reasons for the elevated risk of ischemic events observed in MS may be a genetically or phenotypically reinforced expression of the platelet P2Y₁₂ receptor. In order to analyze the effect of the PAR1 (protease activated receptor type 1) signaling pathway on the expression level of P2Y₁₂, we also analyzed the correlation parameters between P2Y₁₂ expression and the markers of platelet activation in MS induced by selective PAR1 agonist (thrombin receptor activating peptide-6, TRAP-6). Identifying the molecular base responsible for the enlarged pro-thrombotic activity of platelets in SP MS could contribute to the implementation of prevention and targeted treatment, reducing the development of cardiovascular disorders in the course of the disease.

Comparisons between ticagrelor and clopidogrel following percutaneous coronary intervention in patients with acute coronary syndrome: a comprehensive meta-analysis

Background

The efficacy and safety of ticagrelor following percutaneous coronary intervention for patients with acute coronary syndrome remains unclear. This study sought to evaluate clinical outcomes of ticagrelor as part of dual-antiplatelet treatment for these patients.

Methods

PubMed, MEDLINE, Embase, and other Internet sources were searched for eligible citations. The primary end point was major adverse cardiovascular and cerebrovascular events, consisting of cardiovascular death, myocardial infarction, and stroke. The secondary end point was the occurrence of definite/probable stent thrombosis (ST). The risk of bleeding was chosen to be the safety end point.

Results

Eleven clinical trials – six randomized trials and five observational trials – were finally analyzed. A tendency toward reduction in the risk of major adverse cardiovascular and cerebrovascular events was observed only with respect to ticagrelor (OR 0.83, 95% CI 0.66–1.03; P=0.091), which might have resulted from the lower risk of cardiovascular death (OR 0.78, 95% CI 0.68–0.89; P<0.001). The overall incidence of ST differed significantly between the ticagrelor group and the clopidogrel group (OR 0.74, 95% CI 0.59–0.93; P=0.009), but the risk of bleeding, regardless of major or minor bleeding, increased significantly.

Conclusion

As part of dual-antiplatelet treatment following percutaneous coronary intervention, ticagrelor significantly reduced the risk of cardiovascular death and ST in acute coronary syndrome patients, but at the cost of bleeding. More powerful relevant randomized trials are still warranted to guide clinical decision-making.

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.

Ticagrelor versus clopidogrel in East-Asian patients with acute coronary syndromes: a meta-analysis of randomized trials

Aim: To determine whether ticagrelor or clopidogrel provides the best outcomes for East-Asian patients with acute coronary syndrome (ACS). Materials & methods: Identification and interrogation of electronic databases through 26 July 2016 revealed fully randomized and controlled trials wherein primary efficacy end points were major adverse cardiovascular events and all-cause death among East-Asian patients with ACS. Major bleeding and noncoronary artery bypass grafts major bleeding were primary safety end points. Results: Two studies met the inclusion criteria. Compared with clopidogrel, ticagrelor has no statistical difference in the end points of major adverse cardiovascular events (risk ratio [RR]: 1.08; 95% CI: 0.62–1.91; p = 0.7260), myocardial infarction (RR: 1.200; 95% CI: 0.64–2.24; p = 0.5669), stroke (RR: 1.11; 95% CI: 0.46–2.66; p = 0.8165), cardiovascular death (RR: 0.89; 95% CI: 0.48–1.65; p = 0.7150), or all-cause mortality (RR: 0.92; 95% CI: 0.43–1.96; p = 0.8252). When compared with clopidogrel, it was found that ticagrelor provoked marked increases in major bleeding (RR: 1.48; p = 0.0430) and noncoronary artery bypass grafts-associated major bleeding (RR: 1.62; p = 0.0454). Conclusion: Ticagrelor and clopidogrel displayed similar efficacies in ACS presenting patients from East Asia. Administration of ticagrelor also displays some side effects including an increased risk of major bleeding.

The clinical outcomes of triple antiplatelet therapy versus dual antiplatelet therapy for high-risk patients after coronary stent implantation: a meta-analysis of 11 clinical trials and 9,553 patients

Background

The optimal antiplatelet regimen after in-coronary intervention among patients presenting with complex coronary artery lesions or acute coronary syndrome (ACS) has remained unclear. This study sought to evaluate the clinical outcomes of triple antiplatelet treatment (TAPT) (cilostazol added to aspirin plus clopidogrel) in these patients.

Methods

The PubMed, EMBASE, MEDLINE, and other Internet sources were searched for relevant articles. The primary end point was major adverse cardiac events (MACE), including all-cause mortality, myocardial infarction, and target vessel revascularization. The incidence of definite/probable stent thrombosis and bleeding were analyzed as the safety end points.

Results

Eleven clinical trials involving 9,553 patients were analyzed. The risk of MACE was significantly decreased following TAPT after stent implantation in the ACS subgroup (odds ratio [OR]: 0.72; 95% confidence interval [CI]: 0.61–0.85; P<0.001), which might mainly result from the lower risk of all-cause mortality in this subset (OR: 0.62; 95% CI: 0.48–0.80; P<0.001). The risk of bleeding was not increased with respect to TAPT.

Conclusion

TAPT after stent implantation was associated with feasible benefits on reducing the risk of MACE, especially on reducing the incidence of all-cause mortality among patients suffering from ACS, without higher incidence of bleeding. Larger and more powerful randomized trials are still warranted to prove the superiority of TAPT for such patients.

Long-term clinical efficacy and safety of adding cilostazol to dual antiplatelet therapy for patients undergoing PCI: a meta-analysis of randomized trials with adjusted indirect comparisons

OBJECTIVE

To assess the long-term clinical efficacy and safety of adding cilostazol to aspirin plus clopidogrel (triple antiplatelet therapy, TAT) in patients undergoing percutaneous coronary intervention (PCI) and explore its role in the era of new generation adenosine diphosphate (ADP)-receptor antagonists.

METHODS

PUBMED, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for randomized controlled trials (RCTs) comparing TAT versus dual antiplatelet therapy (DAT), followed by a manual search. Then, a meta-analysis of RCTs comparing TAT versus standard DAT in patients undergoing PCI was performed. Furthermore, indirect comparisons of TAT versus new generation ADP-receptor antagonist based DAT (prasugrel or ticagrelor based DAT) were undertaken, with standard DAT as a common comparator. The included end-points were major adverse cardiovascular event (MACE), target lesion revascularization (TLR), target vessel revascularization (TVR), death, myocardial infarction (MI), stent thrombosis, bleeding and other drug adverse events.

RESULTS

Twelve RCTs with a total of 31,789 patients were included. Compared with standard DAT (n = 2551), TAT (n = 2545) significantly reduced the incidence of MACE (OR: 0.56, 95% CI: 0.47-0.68, P < 0.00001), TLR (OR: 0.51, 95% CI: 0.34-0.75, P = 0.0006) and TVR (OR: 0.59, 95% CI: 0.46-0.75, P < 0.0001), and did not change significantly in death (OR: 0.68, 95% CI: 0.44-1.05, P = 0.08), MI (OR: 0.80, 95% CI: 0.45-1.44, P = 0.46), stent thrombosis (OR: 0.61, 95% CI: 0.27-1.36, P = 0.23), major bleeding (OR: 1.42, 95% CI: 0.52-3.85, P = 0.49) and overall bleeding (OR: 1.16, 95% CI: 0.79-1.69, P = 0.45). Compared with prasugrel (n = 6813) or ticagrelor based DAT (n = 6732), TAT (n = 2545) further reduced the incidence of MACE (OR: 0.80, 95% CI: 0.72-0.90, P = 0.0012; OR: 0.83, 95% CI: 0.75-0.92, P = 0.0003, respectively).

CONCLUSIONS

Compared with standard DAT, the long-term use of TAT in patients with PCI gives more benefits in reducing the incidence of MACE, TLR and TVR without increasing bleeding. Furthermore, it might be superior to prasugrel or ticagrelor based DAT in term of MACE, which needs to be confirmed by future studies with direct comparisons.