Effects of cilostazol against the progression of carotid IMT in symptomatic ischemic stroke patients

Cardiovascular protection associated with cilostazol, colchicine and target of rapamycin inhibitors

ABSTRACT

An alteration in extracellular matrix production by vascular smooth muscle cells is a crucial event in the pathogenesis of vascular diseases such as aging-related, atherosclerosis and allograft vasculopathy. The human target of rapamycin (TOR) is involved in the synthesis of extracellular matrix by vascular smooth muscle cells. TOR inhibitors reduce arterial stiffness, blood pressure, and left ventricle hypertrophy and decrease cardiovascular risk in kidney graft recipients and patients with coronary artery disease and heart allograft vasculopathy. Other drugs that modulate extracellular matrix production such as cilostazol and colchicine have also demonstrated a beneficial cardiovascular effect. Clinical studies have consistently shown that cilostazol confers cardiovascular protection in peripheral vascular disease, coronary artery disease, and cerebrovascular disease. In patients with type 2 diabetes, cilostazol prevents the progression of subclinical coronary atherosclerosis. Colchicine reduces arterial stiffness in patients with Familial Mediterranean Fever and patients with coronary artery disease. Pathophysiological mechanisms underlying the cardioprotective effect of these drugs may be related to interactions between the cytoskeleton, TOR signaling and cyclic AMP synthesis that remain to be fully elucidated. Adult vascular smooth muscle cells exhibit a contractile phenotype and produce little extracellular matrix. Conditions that upregulate extracellular matrix synthesis induce a phenotypic switch toward a synthetic phenotype. TOR inhibition with rapamycin reduces extracellular matrix production by promoting the change to the contractile phenotype. Cilostazol increases the cytosolic level of cyclic AMP, which in turn leads to a reduction in extracellular matrix synthesis. Colchicine is a microtubule-destabilizing agent that may enhance the synthesis of cyclic AMP.

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.

Cilostazol: a Review of Basic Mechanisms and Clinical Uses

Primarily used in the treatment of intermittent claudication, cilostazol is a 2-oxyquinolone derivative that works through the inhibition of phosphodiesterase III and related increases in cyclic adenosine monophosphate (cAMP) levels. However, cilostazol has been implicated in a number of other basic pathways including the inhibition of adenosine reuptake, the inhibition of multidrug resistance protein 4, among others. It has been observed to exhibit antiplatelet, antiproliferative, vasodilatory, and ischemic-reperfusion protective properties. As such, cilostazol has been investigated for clinical use in a variety of settings including intermittent claudication, as an adjunctive for reduction of restenosis after coronary and peripheral endovascular interventions, and in the prevention of secondary stroke, although its widespread implementation for indications other than intermittent claudication has been limited by relatively modest effect sizes and lack of studies in western populations. In this review, we highlight the pleiotropic effects of cilostazol and the evidence for its clinical use.

Progress in the Mechanism and Clinical Application of Cilostazol

Cilostazol is a unique platelet inhibitor that has been used clinically for more than 20 years. As a phosphodiesterase type III inhibitor, cilostazol is capable of reversible inhibition of platelet aggregation and vasodilation, has antiproliferative effects, and is widely used in the treatment of peripheral arterial disease, cerebrovascular disease, percutaneous coronary intervention, etc. This article briefly reviews the pharmacological mechanisms and clinical application of cilostazol.

Design and Rationale of the Intima-Medial Thickness Sub-Study of the PreventIon of CArdiovascular Events in iSchemic Stroke Patients with High Risk of Cerebral hemOrrhage (PICASSO-IMT) Study

BACKGROUND

Atherosclerosis is one of the main mechanisms of stroke and cardiovascular diseases and is associated with increased risk of recurrent stroke and cardiovascular events. Intima-medial thickness (IMT) is a well-known surrogate marker of atherosclerosis and has been used to predict stroke and cardiovascular events. However, the clinical significance of IMT and IMT change in stroke has not been investigated in well-designed studies. The PreventIon of CArdiovascular events in iSchemic Stroke patients with high risk of cerebral hemOrrhage-Intima-Media Thickness (PICASSO-IMT) sub-study is designed to investigate the effects of cilostazol, probucol, or both on IMT in patients with stroke.

METHODS

PICASSO-IMT is a prospective sub-study of the PICASSO study designed to measure IMT and plaque score at 1, 13, 25, 37, and 49 months after randomization.

RESULTS

The primary outcome is the change in mean carotid IMT, which is defined as the mean of the far-wall IMTs of the right and left common carotid arteries, between baseline and 13 months after randomization.

CONCLUSION

PICASSO-IMT will provide the largest IMT data set in a stroke population and will provide valuable information about the clinical significance of IMT in patients with ischemic stroke.

Meta-Analysis of Studies Evaluating the Effect of Cilostazol on Major Outcomes After Carotid Stenting

PURPOSE

To evaluate the effect of cilostazol on major outcomes after carotid artery stenting (CAS).

METHODS

A systematic literature review was conducted conforming to established criteria in order to identify articles published prior to May 2015 evaluating major post-CAS outcomes in patients treated with cilostazol vs patients not treated with cilostazol. Major outcomes included in-stent restenosis (ISR) within the observation period, the revascularization rate, major/minor bleeding, and the myocardial infarction/stroke/death rate (MI/stroke/death) at 30 days and within the observation period. Data were pooled for all studies containing adequate data for each outcome investigated; effect estimates are presented as the odds ratios (ORs) and 95 confidence intervals (CI).

RESULTS

Overall, 7 studies pertaining to 1297 patients were eligible. Heterogeneity was low among studies so a fixed-effect analysis was conducted. Six studies (n=1233) were compared for the ISR endpoint, showing a significantly lower ISR rate with cilostazol treatment after a mean follow-up of 20 months (OR 0.158, 95% CI 0.072 to 0.349, p<0.001). Five studies (n=649) were compared regarding 30-day MI/stroke/death (OR 0.724, 95% CI 0.293 to 1.789, p=0.484) and 3 studies (n=1076) were analyzed regarding MI/stroke/death within the entire follow-up period (OR 0.768, 95% CI 0.477 to 1.236, p=0.276); no significant difference was found between the groups. Data on bleeding rates and revascularization rates post ISR were inadequate to conduct further analysis.

CONCLUSION

Cilostazol seems to decrease total ISR rates in patients undergoing CAS without affecting MI/stroke/death events, both in the early and late settings.

Cilostazol research in Asia: can it be applied to European and American patients?

Cilostazol is an antiplatelet drug often used in Asian countries like Korea, Japan, and China. However, it is rarely used in the west. Cilostazol inhibits phosphodiesterase, increases cyclic AMP concentrations, and consequently inhibits platelet aggregation. Interestingly, it also has vasodilatory activity, inhibits vascular smooth muscle proliferation, and protects the endothelium. Studies in Asia have shown that cilostazol is effective in the secondary prevention of stroke. Moreover, it is significantly less likely to cause bleeding complications than aspirin. Additional trials have shown that cilostazol is effective in the prevention of intracranial atherosclerosis progression. Unfortunately, cilostazol has rarely been studied in non-Asian stroke patients and, accordingly, the benefits of cilostazol are less well appreciated in Europe and America than in Asia. Although further studies are required, we suggest that at least some stroke patients (e.g., patients prone to bleeding, patients with intracranial atherosclerosis, etc.) may readily benefit from cilostazol regardless of ethnicity.

Advancements in understanding the mechanisms of symptomatic lacunar ischemic stroke: translation of knowledge to prevention strategies

Symptomatic lacunar ischemic stroke (25% of all brain infarctions) results from occlusion of a single penetrating artery by microatheromas or lipohyalinosis and rarely from an intracranial atheromatous branch disease. Recurrent lacunar stroke may be associated with more severe clinical features and has been involved in producing lacunar state and vascular subcortical dementia. In the first multicenter randomized clinical trial (SPS3) focused on stroke prevention among patients with recent lacunar stroke, the addition of clopidogrel to aspirin not only did not reduced significantly the risk of recurrent stroke, but also increased significantly the likelihood of hemorrhage and fatal outcome. If lacunar stroke is primarily non-atherothromboembolic, secondary prevention aimed at preventing atheroma progression may not be very effective. The efficacy of drugs that improve endothelial function in lacunar stroke patients remains to be studied in the future.

Adaptation of the main peripheral artery and vein to long term confinement (Mars 500)

Purpose

The objective was to check if 520 days in confinement (MARS 500), may affect the main peripheral arterial diameter and wall thickness and the main vein size.

Method

Common carotid (CC) femoral artery (FA) portal vein (PV), jugular (JG), femoral vein (FV) and tibial vein were assessed during MARS 500 by echography, performed by the subjects. A hand free volumic echographic capture method and a delayed 3D reconstruction software developed by our lab were used for collecting and measuring the vascular parameters.

Results

During the MARS 500 experiment the subjects performed 6 sessions among which 80% of the echographic data were of sufficient quality to be processed. No significant change was found for the Common carotid, Jugular vein, femoral artery, femoral vein, portal vein, and tibial vein diameter. CC and FA IMT (intima media thickness) were found significantly increased (14% to 28% P<0.05) in all the 6 subjects, during the confinement period and also at +2 days after the confinement period, but there was no significant difference 6 month later compare to pre MARS 500.

Conclusion

The experiment confirmed that even untrained to performing echography the subjects were able to capture enough echographic data to reconstruct the vessel image from which the parameters were measured. The increase in both CC and FA IMT should be in relation with the stress generated by the confined environment or absence of solar radiation, as there was no change in gravity, temperature and air in the MARS 500 module, and minor changes in physical exercise and nutrition.

The Response of Carotid Intima-Media Thickness to Medical Treatment Is Correlated with That of Intracranial Atherosclerosis

Background and Purpose

Intracranial atherosclerotic stenosis (ICAS) is considered as a major cause of stroke. The carotid intima-media thickness (CIMT), which accurately reflects the burden of generalized atherosclerosis, is also associated with stroke. The aim of this study was to determine the association between the CIMT and ICAS responses to medical treatment.

Methods

This study constituted part of the "Trial of cilostazol in symptomatic intracranial arterial stenosis"-2 that evaluated the ICAS response after randomized antiplatelet treatment. Magnetic resonance angiography and CIMT measurement were performed at baseline and after 7 months of treatment. CIMT was measured using semiautomated software, and was presented as maximum (CIMT-max) and average (CIMT-ave) values. The change in CIMT was compared relative to the ICAS response (i.e., progression, no-change, and regression). Ordinal logistic regression and analysis of covariance (ANCOVA) were used to analyze the association between the responses.

Results

Among the 101 enrolled patients, 85 underwent follow-up CIMT measurement. CIMT increased most in the ICAS progression group (CIMT-max: 0.09±0.23, CIMT-ave: 0.04±0.12), and to a lesser degree in the no-change group (CIMT-max: 0.02±0.16, CIMT-ave: 0.02±0.11), but decreased in patients with ICAS regression (CIMT-max: -0.04±0.11, CIMT-ave: -0.03±0.07; CIMT-max: p=0.010, CIMT-ave: p=0.015). Ordinal logistic regression analysis demonstrated that the change in CIMT-max was independently associated with the ICAS response (p=0.032). However, the ANCOVA revealed that the reverse was not true, in that the ICAS response was not independently associated with the change in CIMT after adjusting for confounding factors.

Conclusions

The ICAS response may be associated with the CIMT response to medical treatment.