Comparison of ticlopidine and cilostazol for the prevention of restenosis after percutaneous transluminal coronary angioplasty

Update on Cilostazol: A Critical Review of Its Antithrombotic and Cardiovascular Actions and Its Clinical Applications

Cilostazol, a phosphodiesterase III inhibitor, has vasodilating and antiplatelet properties with a low rate of bleeding complications. It has been used over the past 25 years for improving intermittent claudication in patients with peripheral artery disease (PAD). Cilostazol also has demonstrated efficacy in patients undergoing percutaneous revascularization procedures for both PAD and coronary artery disease. In addition to its antithrombotic and vasodilating actions, cilostazol also inhibits vascular smooth muscle cell proliferation via phosphodiesterase III inhibition, thus mitigating restenosis. Accumulated evidence has shown that cilostazol, due to its "pleiotropic" effects, is a useful, albeit underutilized, agent for both coronary artery disease and PAD. It is also potentially useful after ischemic stroke and is an alternative in those who are allergic or intolerant to classical antithrombotic agents (eg, aspirin or clopidogrel). These issues are herein reviewed together with the pharmacology and pharmacodynamics of cilostazol. Large studies and meta-analyses are presented and evaluated. Current guidelines are also discussed, and the spectrum of cilostazol's actions and therapeutic applications are illustrated.

Comparison of cilostazol versus ticlopidine following coronary stenting in patients with coronary heart disease: A meta-analysis of randomized controlled trials

Previous studies have shown that the combination of cilostazol and aspirin may be a more effective regimen than ticlopidine plus aspirin in the prevention of late restenosis and acute or subacute stent thrombosis following coronary stenting; however, individually published results are inconclusive. The aim of this meta-analysis was to compare the differences in late restenosis and stent thrombosis between cilostazol plus aspirin and ticlopidine plus aspirin for patients with coronary heart disease (CHD) following coronary stenting. A literature search of Pubmed, Embase, Web of Science and Chinese BioMedicine (CBM) databases was conducted from 1998 to March 1, 2013 and statistical analysis was performed using Stata statistical software, version 12.0. Twelve randomized controlled trials were included in the study, with a total of 2,708 patients with CHD following coronary stenting. The patient population comprised 1,371 patients treated with cilostazol plus aspirin and 1,337 patients treated with ticlopidine plus aspirin. The meta-analysis showed that cilostazol plus aspirin demonstrated a lower rate of restenosis than ticlopidine plus aspirin [odds ratio (OR)=0.83, 95% confidence interval (CI)=0.69–0.99, P=0.047]. A significant difference was also observed in the average percent diameter stenosis between cilostazol plus aspirin and ticlopidine plus aspirin [standardized weight difference (SMD)= −0.57, 95% CI=−0.92, −0.23, P=0.001). However, there were no significant differences in the rates of acute or subacute stent thrombosis between cilostazol plus aspirin and ticlopidine plus aspirin. The present meta-analysis suggests that cilostazol plus aspirin may result in a lower restenosis rate and percent diameter stenosis than ticlopidine plus aspirin for patients with CHD following coronary stenting.

Efficacy of cilostazol in reducing restenosis in patients undergoing contemporary stent based PCI: a meta-analysis of randomised controlled trials

AIMS

Cilostazol has been associated with reduction in restenosis in patients undergoing coronary and peripheral arterial angioplasty. Our objective was to evaluate the impact of cilostazol on restenosis in patients undergoing contemporary PCI with bare metal (BMS) or drug eluting stents (DES) and treated with aspirin and thienopyridine.

METHODS AND RESULTS

Ten randomised trials (n=2,809 patients) comparing triple antiplatelet therapy (aspirin, thienopyridine and cilostazol) with standard dual antiplatelet therapy were included. Summary risk ratios for restenosis, late loss, target lesion revascularisation (TLR) and target vessel revascularisation (TVR) were calculated using fixed-effects models. Cilostazol was associated with a significant reduction in late loss in BMS (mean difference 0.24 mm, 95% CI 0.15-0.33, p<0.001) and DES groups (mean difference 0.12 mm, 95% CI 0.07-0.18, p<0.001). Cilostazol therapy was associated with a significant reduction in angiographic restenosis (Odds ratio [OR] 0.52, 95% CI 0.41- 0.66, p<0.001) with consistent benefits in patients treated with BMS (OR 0.49, 95% CI 0.35-0.70, p<0.001) or DES (OR 0.54, 95% CI 0.38-0.76, p=0.001). Addition of cilostazol to dual antiplatelet therapy was associated with a significant reduction in TLR (OR 0.38, 95% CI 0.25-0.58, p<0.001), with no difference in subacute stent thrombosis (OR 1.91, 95% CI 0.33-11.08, p=0.47), or major bleeding (OR 0.87, 95% CI 0.44-1.74, P=0.69) but with an increased risk of skin rash (OR 3.67, 95% CI 1.86-7.24, p<0.001).

CONCLUSIONS

Cilostazol in addition to dual antiplatelet therapy is associated with a reduction in angiographic restenosis in patients undergoing stent based PCI. This inexpensive drug may be particularly beneficial in patients who are at high risk of restenosis and it should undergo further evaluation in large, definitive randomised controlled trials.

Platelet P2Y(12) receptor influences the vessel wall response to arterial injury and thrombosis

BACKGROUND

Platelets are believed to play an important role in atherogenesis and the vessel response to vascular injury. The P2Y(12) receptor (P2Y(12)) plays a central role in amplifying platelet aggregation, dense granule and alpha-granule secretion, P-selectin expression, microparticle formation, and procoagulant membrane changes, regardless of the activating stimulus. We hypothesized that P2Y(12) deficiency might reduce the vessel wall response to vascular injury as well as thrombosis in murine vascular injury models.

METHODS AND RESULTS

P2Y(12)-deficient (-/-) mice and littermate controls (+/+) were bred on a C57 BL/6 background. In vivo murine models of arterial injury were employed alone and in combination with bone marrow transplantation to investigate the role of P2Y(12) in the vessel wall response to arterial injury and thrombosis. At 21 days after ferric chloride injury, neointima formation in P2Y(12)(-/-) arteries was significantly less than that observed in control strain arteries (P<0.025). In agreement with this, the intima-media ratio was significantly greater in femoral wire-injured arteries from P2Y(12)(+/+) compared with P2Y(12)(-/-) animals (P<0.05). Bone marrow transplantation was used to examine the importance of vessel wall P2Y(12) versus platelet P2Y(12). Analysis of arterial sections from chimeric animals at 21 days after injury revealed a smaller intima-media ratio in -/- to +/+ animals than in the positive (+/+ to +/+) control group (P<0.01).

CONCLUSIONS

These data demonstrate a role for platelet P2Y(12) in the vessel wall response to arterial injury and thrombosis. This illustrates the manner in which platelets may contribute to atherogenesis and restenosis.

Systematic review and meta-analysis of randomized clinical trials appraising the impact of cilostazol after percutaneous coronary intervention

BACKGROUND

Drug-eluting stents reduce the risk of restenosis after percutaneous coronary intervention (PCI) but may pose a risk of thrombosis. Cilostazol, an oral antiplatelet agent with pleiotropic effects including inhibition of neointimal hyperplasia, could hold the promise of preventing both restenosis and thrombosis. We systematically reviewed randomized clinical trials (RCTs) on the angiographic and clinical impact of cilostazol after PCI.

METHODS

We searched RCT in BioMedCentral, CENTRAL, clinicaltrials.gov, EMBASE, and PubMed (November 2007). Coprimary end points were binary angiographic restenosis and repeat revascularization, abstracted and pooled by means of random-effect relative risks (RRs). Small study/publication bias was appraised with multiple methods.

RESULTS

A total of 23 RCTs were included (5428 patients), with median follow-up of 6 months. Pooled analysis showed that cilostazol was associated with statistically significant reductions in binary angiographic restenosis (RR = 0.60 [0.49-0.73], P < .001) and repeat revascularization (RR = 0.69 [0.55-0.86], P = .001). Cilostazol appeared also safe, with no significant increase in the risk of stent thrombosis (RR = 1.35 [0.71-2.57], P = .36) or bleeding (RR = 0.71 [0.43-1.16], P = .17). However, small study bias was evident for both binary restenosis (P < .001) and repeat revascularization (P < .001), suggesting that at least part of the apparent benefits of cilostazol could be due to this type of confounding effect.

CONCLUSIONS

Cilostazol appears effective and safe in reducing the risk of restenosis and repeat revascularization after PCI, but available evidence is limited by small study effects. Awaiting larger RCTs, this inexpensive treatment can be envisaged in selected patients in which drug-eluting stents are contraindicated or when there is a need for neointimal hyperplasia inhibition.

RACTS: a prospective randomized antiplatelet trial of cilostazol versus ticlopidine in patients undergoing coronary stenting: long-term clinical and angiographic outcome

We compared the efficacy of cilostazol for the prevention of late restenosis and acute or subacute stent thrombosis with that of ticlopidine. Cilostazol has been used for antiplatelet therapy after coronary stent implantation, but the results are controversial. Patients scheduled for stent implantation were randomly assigned to receive either cilostazol (100 mg twice daily for 6 months, n=201) or ticlopidine (250 mg twice daily for 1 month, n=196). All patients also received oral aspirin (100 mg once daily for 6 months). Coronary angiography was performed at baseline and immediately and 6 months after coronary stenting. Clinical follow-up was continued up to 9 months postprocedure. There was no significant difference in the composite incidence of death, myocardial infarction, stroke, and stent thrombosis between the 2 groups [cilostazol (1.5%) versus ticlopidine (3.6%), P=0.216], but the target lesion revascularization rate per patient was significantly lower in the cilostazol group than in the ticlopidine group (22.9% vs 32.7%, P=0.030) 9 months post-coronary stenting. Medication withdrawn because of drug-related side effects tended to be higher in the ticlopidine group than that in the cilostazol group (3.5% vs 8.2%, P=0.054). At follow-up angiography, the minimal luminal diameters (2.31+/-1.06 vs 2.10+/-1.16, P=0.057) tended to be larger and the restenosis rates lower (23.3% vs 30.9%, P=0.086) in the cilostazol group than in the ticlopidine group. Aspirin plus cilostazol is a comparable antithrombotic regimen to aspirin plus ticlopidine after elective coronary stenting, but the rate of target lesion revascularization was significantly lower in the cilostazol group than in the ticlopidine group.

Preclinical restenosis models and drug-eluting stents: still important, still much to learn

Percutaneous coronary intervention continues to revolutionize the treatment of coronary atherosclerosis. Restenosis remains a significant problem but may at last be yielding to technologic advances. The examination of neointimal hyperplasia in injured animal artery models has helped in our understanding of angioplasty and stenting mechanisms, and as drug-eluting stent (DES) technologies have arrived, they too have been advanced through the study of animal models. These models are useful for predicting adverse clinical outcomes in patients with DESs because suboptimal animal model studies typically lead to problematic human trials. Similarly, stent thrombosis in animal models suggests stent thrombogenicity in human patients. Equivocal animal model results at six or nine months occasionally have been mirrored by excellent clinical outcomes in patients. The causes of such disparities are unclear but may result from differing methods, including less injury severity than originally described in the models. Ongoing research into animal models will reconcile apparent differences with clinical trials and advance our understanding of how to apply animal models to clinical stenting in the era of DESs.