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 Medication withdrawn because of drug-related side effects tended to be higher in the ticlopidine group than that in the cilostazol group (3.5% vs 8.2%, P=0.054).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.

The vulnerable carotid artery plaque: current imaging methods and new perspectives

BACKGROUND AND PURPOSE

Atherosclerosis is a diffuse, chronic inflammatory disorder that involves the vascular, metabolic, and immune systems and leads to plaque vulnerability. The traditional risk assessment relies on clinical, biological, and conventional imaging tools. However, these tools fall short in predicting near-future events in patients with vulnerable carotid artery plaque.

METHODS

In current clinical practice, anatomic imaging modalities, such as B-mode ultrasound, spiral computed tomography angiography, and high-resolution MRI, can identify several morphological features characteristic of the vulnerable plaque but give little or no information regarding molecular and cellular mechanisms.

RESULTS

This review is dedicated to factors involved in carotid artery plaque vulnerability and to new imaging methods that target this condition. Our aim is to describe the following: (1) conventional pathologic and imaging markers predictive of plaque vulnerability; (2) the role of relevant biological, genetic, and mechanical factors; (3) the potential of new imaging methods; and (4) current and emerging treatments.

CONCLUSIONS

A multimodal assessment of plaque vulnerability involving the combination of systemic markers, new imaging methods that target inflammatory and thrombotic components, and the potential of emerging therapies may lead to a new stratification system for atherothrombotic risk and to a better prevention of atherothrombotic stroke.

Role of adjunct pharmacologic therapy in the era of drug-eluting stents

The success of percutaneous coronary intervention (PCI) has historically been limited by a relatively high rate of restenosis, a response of the coronary artery to trauma induced during PCI. Bare-metal stents, by providing a supportive intravascular scaffolding, have significantly reduced the incidence of restenosis compared with traditional balloon PCI. However, significant loss of lumen within the bare-metal device (in-stent restenosis) occurs in 10-30% of patients within 6 months of the procedure. The recent introduction of drug-eluting stents, permitting local delivery of high concentrations of immunosuppressive or anti-proliferative agents, promises to prevent the processes underlying restenosis. Although these devices have been successful in providing an incremental reduction in rates of restenosis, they are expensive. To date, clinical trials of pharmacologic treatment have failed to demonstrate a clinically significant impact on restenosis. Recently, results of the Cilostazol for Restenosis (CREST) trial, a randomized, double-blind study, show that cilostazol reduces the risk of restenosis in patients who receive bare-metal stents, including high-risk patients. Effective adjunct pharmacologic therapy to prevent in-stent restenosis, therefore, remains desirable, particularly in patients receiving bare-metal stents, and potentially in patients receiving drug-eluting stents who are at high risk for restenosis (i.e., those with diabetes, long lesions, and small vessels).

A scientific rationale for the CREST trial results: evidence for the mechanism of action of cilostazol in restenosis

The Cilostazol for RESTenosis (CREST) clinical trial was initiated to evaluate the efficacy of cilostazol, an antiplatelet drug, in inhibiting restenosis after stent implantation in a native coronary artery as evaluated by quantitative coronary angiography. Preliminary results suggest that cilostazol reduces restenosis by 36% over standard therapy alone. Restenosis after coronary stenting is primarily attributed to neointimal formation. Cilostazol decreases the activity of phosphodiesterase type 3, leading to the accumulation of cyclic adenosine monophosphate, which initiates a cascade of events including upregulation of anti-oncogenes p53 and p21 and upregulation of hepatocyte growth factor (HGF). The increase in p53 protein blocks cell cycle progression and induces apoptosis in vascular smooth muscle cells (VSMCs), leading to an antiproliferative effect. Upregulation of local HGF stimulates rapid regeneration of endothelial cells, which inhibits neointimal formation via two mechanisms: inhibition of abnormal VSMC growth and improvement of endothelial function. These mechanisms may be responsible for the improvement in restenosis shown in the CREST trial and a number of other trials in patients who underwent percutaneous transluminal coronary angioplasty. These effects, in addition to antithrombotic and vasodilatory attributes of cilostazol, make it a potentially viable treatment option for preventing restenosis following coronary stenting.

Coronary Stent Restenosis in Patients Treated With Cilostazol

Background— Restenosis after implantation of coronary artery stents remains a significant clinical problem. We undertook a randomized, double-blind, placebo-controlled trial to determine whether cilostazol, a drug that suppresses intimal proliferation, would reduce renarrowing in patients after stent implantation in native coronary arteries.

Methods and Results— We assigned 705 patients who had successful coronary stent implantation to receive, in addition to aspirin, cilostazol 100 mg BID or placebo for 6 months; clopidogrel 75 mg daily was administered to all patients for 30 days. Restenosis was determined by quantitative coronary angiography at 6 months. The minimal luminal diameter at 6 months for cilostazol-treated patients was 1.77 mm for the analysis segment (stent plus 5-mm borders) compared with 1.62 mm in the placebo group ( P =0.01). Restenosis, defined as ≥50% narrowing, occurred in 22.0% of patients in the cilostazol group and in 34.5% of the placebo group ( P =0.002), a 36% relative risk reduction. Restenosis was significantly lower in cilostazol-treated diabetics (17.7% versus 37.7%, P =0.01) and in those with small vessels (23.6% versus 35.2%, P =0.02), long lesions (29.9% versus 46.6%, P =0.04), and left anterior descending coronary artery site (19.3% versus 39.8%, P =0.001). There was no difference in bleeding, rehospitalization, target-vessel revascularization, myocardial infarction, or death.

Conclusions— Treatment with the drug cilostazol resulted in a significantly larger minimal luminal diameter and a significantly lower binary restenosis rate compared with placebo-treated patients. These favorable effects were apparent in patients at high risk for restenosis.

Health care resources and costs for treating peripheral artery disease in a managed care population: results from analysis of administrative claims data

OBJECTIVE

Peripheral arterial disease (PAD) is associated with high rates of morbidity and mortality and serves as an important marker for advanced systemic atherosclerosis accompanied by symptomatic or asymptomatic ischemia of the coronary, cerebral, and visceral vasculature. There are little published data on the use of health care resources and costs attributable to PAD. The objectives of this study were to evaluate, from a societal perspective, PAD-related health care resource utilization and to determine the total annualized costs and cost components for patients with PAD, with particular attention to the key outcomes of myocardial infarction (MI), transient ischemic attacks (TIA), stroke, and amputations.

METHODS

This study examined medical, hospital and outpatient, and pharmacy claims from a large managed care database with dates of service from January 1, 1999, through August 31, 2003. Patients with PAD were identified from claims using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes (primary or secondary codes), ICD-9-CM procedure codes, current procedural terminology (CPT) codes, or by a pharmacy claim for cilostazol or pentoxifylline. The index date for each patient was the first occurrence of either a medical claim for PAD or a pharmacy claim for 1 of the 2 drugs. Patients were required to be a minimum of 18 years old with continuous plan eligibility. The prevalence of PAD in adults in a managed care setting was also determined, as were annual rates for the key outcomes of MI, TIA, stroke, and amputations. Health care resource utilization and costs were calculated for PAD patients after the index date for a period of at least 12 months per patient for medications, outpatient/physician office visits, laboratory/diagnostic procedures, emergency department visits, and hospitalization. Cost was defined as the allowed charge on each administrative claim, including the amount paid by the insurer plus the amount paid by the health plan members (copay, deductible, and coinsurance).

RESULTS

Prior to application of exclusion criteria for patients aged 18 years or older and the minimum period of continuous eligibility, the overall prevalence of PAD was 1.18% of the total managed care organization population.s 6.67 million members. The PAD study cohort consisted of 30,561 patients with a mean age of 70.7 years at index. The most common comorbidities identified in the preindex period for these PAD patients included hypertension (67% of patients); metabolic disorders/hypercholesterolemia (57%); heart disease including cardiomyopathy, dysrhythmias, and heart failure (55%); and ischemic heart disease (47%). Over a mean postindex period of 25.2 months (median 23.4 months), the total mean annualized PAD-related cost was $5,955 per patient per year (PPPY). Hospitalizations accounted for the largest component cost category, averaging $4,442 PPPY or 75% of the total annualized PAD-related cost per PAD patient. PAD-related noncoronary procedures averaged $729 PPPY (12.2% of total annual PAD-related costs), and PAD-related medications (including antihypertensives and lipid-lowering therapy) totaled $610 (10.2% of total annual costs), including $313 PPPY for antihypertensives and $207 for lipid-lowering therapy. For the subgroup of 24,075 newly identified PAD patients, 8,479 (35.2%) were hospitalized during an average 25.2 months of follow-up, with the mean time to first hospitalization of 8.9 months.

CONCLUSIONS

Approximately 75% of the total PAD-related patient cost in an average of 25 months of follow-up is contributed by hospital costs, and 35% of patients newly diagnosed with PAD experienced a hospitalization in a mean of 8.9 months after the index diagnosis. Based upon mean annual health and member costs of only $313 PPPY for antihypertensives and $207 for lipid-lowering therapy, drug therapy in PAD patients may be underutilized.

Triple Versus Dual Antiplatelet Therapy After Coronary Stenting

OBJECTIVES

We evaluated safety and efficacy of triple antiplatelet therapy with aspirin, clopidogrel, or ticlopidine and cilostazol after coronary stenting.

BACKGROUND

Triple antiplatelet therapy might have beneficial effect to prevent thrombotic complications in patients undergoing coronary stenting.

METHODS

Patients undergoing successful coronary stenting were divided into dual antiplatelet therapy (aspirin plus clopidogrel or ticlopidine, group I, n = 1,597) and triple antiplatelet therapy (aspirin plus clopidogrel or ticlopidine plus cilostazol, group II, n = 1,415) groups. The primary end point included death, myocardial infarction, target lesion revascularization, or stent thrombosis within 30 days. The secondary end point was side effects of study drugs, including major bleeding, vascular complication, hepatic dysfunction, and hematological complications.

RESULTS

Multi-vessel stenting and the use of long stents were more prevalent in group II than in group I. The primary end point was 0.8% in group I and 0.3% in group II (p = 0.085). Stent thrombosis within 30 days was significantly lower in group II (n = 1, 0.1%) than in group I (n = 9, 0.5%; p = 0.024). The independent predictors of stent thrombosis were primary stenting (odds ratio [OR] 7.9, 95% confidence interval [CI] 2.0 to 30.8, p = 0.003) and triple therapy (OR 0.12, 95% CI 0.015 to 0.98, p = 0.048). The overall adverse drug effects, including major bleeding, neutropenia, and thrombocytopenia, were no different between two groups (1.8% vs. 2.6%, p = 0.104).

CONCLUSIONS

Compared with the dual antiplatelet regimen, triple antiplatelet therapy seemed to be more effective in preventing thrombotic complications after stenting without an increased risk of side effects. Triple antiplatelet therapy might be safely applied in patients or lesions with a high risk of stent thrombosis.

[Effects of cilostazol on long-term clinical outcomes after coronary stenting]

OBJECTIVE

To evaluate the effects of cilostazol on long-term clinical outcomes in patients underwent coronary stent implantation.

METHODS

One hundred patients who underwent coronary stenting were randomly assigned to receive cilostazol 200 mg/d for 6 months (n = 50) or ticlopidine 500 mg/d for 1 month (n = 50). Aspirin 100 mg/d was administrated concomitantly with cilostazol or ticlopidine. Angiographic follow-up was carried out at 6 months and clinical follow-up for 3 years after stenting.

RESULTS

Angiographic restenosis occurred in 5 of 34 patients (14.7%) in cilostazol group and 10 of 37 patients (27.0%) in ticlopidine group (P = 0.204). At the end of three-year follow-up, the incidence of major adverse cardiac and cerebral events (MACCE) was greatly reduced in cilostazol group compared with ticlopidine group (16% vs 36%, P = 0.023). Changes of Seattle angina questionnaire (SAQ) physical limitation score showed no significant difference between two groups (21.8 +/- 12.3 vs 16.8 +/- 15.9, P = 0.086). However, changes the improvement of angina frequency score much more was significant in cilostazol group (22.6 +/- 12.7) compared with that in ticlopidine group (16.1 +/- 13.3, P = 0.015). Recurrent angina occurred in 38% of patients in cilostazol group and 54% in ticlopidine group, respectively (P = 0.105). Readmission due to cardiac and cerebral vascular diseases was much less in cilostazol group than that in ticlopidine group (20% vs 40%, P = 0.029).

CONCLUSIONS

Cilostazol treatment significantly reduced MACCE and improved the quality of life pf patients in three-year clinical follow-up after coronary stenting.

Drug Therapy in Brugada Syndrome

Sudden cardiac death in healthy individuals with structurally normal hearts and a characteristic morphology of the QRS complex resembling a right bundle branch block with elevation of the ST segment in V1 to V3 is known as Brugada syndrome (BrS). Although placement of an implantable cardioverter-defibrillator is considered the only effective therapy for symptomatic patients, some authors have repeatedly reported a beneficial effect of quinidine and isoproterenol in patients with BrS. Also, isolated case reports on the usefulness of cilostazol, sotalol, and mexiletine have been described. The present article reviews the mechanisms by which these drugs may act and their role in the pharmacotherapy of BrS. Other possible agents, mainly I(2) blockers, are also reviewed.

Cost effectiveness of cilostazol compared with naftidrofuryl and pentoxifylline in the treatment of intermittent claudication in the UK

OBJECTIVE

To estimate the cost effectiveness of cilostazol (Pletal) compared to naftidrofuryl and pentoxifylline (Trental) in the treatment of intermittent claudication in the UK.

DESIGN AND SETTING

This was a modelling study on the management of patients with intermittent claudication who are 40 years of age or above and have at least six months history of symptomatic intermittent claudication, secondary to lower extremity arterial occlusive disease. The study was performed from the perspective of the UK's National Health Service (NHS).

METHODS

Clinical outcomes attributable to managing intermittent claudication were obtained from the published literature and resource utilisation estimates were derived from a panel of vascular surgeons. Using decision analytical techniques, a decision model was constructed depicting the management of intermittent claudication with cilostazol, naftidrofuryl and pentoxifylline over 24 weeks in the UK. The model was used to estimate the cost effectiveness (at 2002/2003 prices) of cilostazol relative to the other treatments.

MAIN OUTCOME MEASURES AND RESULTS

Starting treatment with cilostazol instead of naftidrofuryl is expected to increase the percentage improvement in maximal walking distance by 32% (from 57% to 75%) for a 12% increase in NHS costs (from 801 pounds sterling to 895 pounds sterling). Treatment with cilostazol instead of pentoxifylline is expected to increase the percentage improvement in maximal walking distance by 67% (from 45% to 75%) and reduce NHS costs by 2% (from 917 pounds sterling to 895 pounds sterling). Treatment with naftidrofuryl instead of pentoxifylline is expected to increase the percentage improvement in maximal walking distance by 27% (from 45% to 57%) and decrease NHS costs by 14% (from 917 pounds sterling to 801 pounds sterling).

CONCLUSION

Within the limitations of our model, starting treatment with cilostazol is expected to be a clinically more effective strategy for improving maximal walking distance at 24 weeks than starting treatment with naftidrofuryl or pentoxifylline and potentially the most cost effective strategy. Moreover, the acquisition cost of a drug should not be used as an indication of the cost effectiveness of a given method of care.

Cilostazol improves endothelium-derived hyperpolarizing factor-type relaxation in mesenteric arteries from diabetic rats

We previously reported that in mesenteric arteries from streptozotocin (STZ)-induced diabetic rats that 1) endothelium-derived hyperpolarizing factor (EDHF)-type relaxation is impaired, possibly due to a reduced action of cAMP via increased phosphodiesterase 3 (PDE3) activity (Matsumoto T, Kobayashi T, and Kamata K. Am J Physiol Heart Circ Physiol 285: H283-H291, 2003) and that 2) PKA activity is decreased (Matsumoto T, Wakabayashi K, Kobayashi T, and Kamata K. Am J Physiol Heart Circ Physiol 287: H1064-H1071, 2004). Here we investigated whether chronic treatment with cilostazol, a PDE3 inhibitor, improves EDHF-type relaxation in mesenteric arteries isolated from STZ rats. We found that in such arteries 1) cilostazol treatment (2 wk) improved ACh-, A-23187-, and cyclopiazonic acid-induced EDHF-type relaxations; 2) the ACh-induced cAMP accumulation was transient and sustained in arteries from cilostazol-treated STZ rats; 3) the EDHF-type relaxation was significantly decreased by a PKA inhibitor in the cilostazol-treated group, but not in the cilostazol-untreated group; 4) cilostazol treatment improved both the relaxations induced by cAMP analogs and the PKA activity level; and 5) PKA catalytic subunit (Cat-alpha) protein was significantly decreased, but the regulatory subunit RII-beta was increased (and the latter effect was significantly decreased by cilostazol treatment). These results strongly suggest that cilostazol improves EDHF-type relaxations in STZ rats via an increase in cAMP and PKA signaling.

Effects of Cilostazol on Human Venous Smooth Muscle

In this study, we evaluated the effect of therapeutic doses of cilostazol on human venous smooth muscle. Saphenous vein rings (two to four per patient sample) were suspended in tissue baths for isometric tension recordings. At the beginning of the experiment, optimal tension for isometric contraction was achieved for each ring in a stepwise fashion in the presence of norepinephrine (10(-2) M). Norepinepherine was then added cumulatively in half-molar increments and isometric tension developed by the rings was measured, thereby obtaining a dose-response curve. Following washout and reequilibration, the rings were precontracted with a 30-50% submaximal dose of norepinepherine determined from the dose-response curve and allowed to contract until a stable plateau was reached. Cilostazol was then added in a cumulative manner (680-2,720 microg/L), and the tension generated was recorded. A total of 76 venous rings were tested, and all relaxed in the presence of cilostazol. The amount of relaxation increased as the concentration of cilostazol increased. Relaxation of 15 +/- 1.9% (mean +/- SEM) at low cilostazol doses (680 microg/L) to 37+/-3% at high cilostazol doses (2,720 microg/L) was demonstrated. A second finding of this study was demonstrated when the patient samples were divided according to the presence or absence of risk factors for arteriosclerosis. The specific risk factors examined included diabetes mellitus, smoking, hypercholesterolemia, and hypertension. The presence or absence of hypertension (n = 52) or hypercholesterolemia (n = 18) did not affect the amount of relaxation of the venous rings. Smokers (n = 46) had less relaxation 16 +/- 2.4% (680 microg/L) to 41 +/- 3.6% (2,720 microg/L) compared to nonsmokers (n = 53) who relaxed 22 +/- 3.5% (680 microg/L) to 48 +/- 5.7% (2720 microg/L). This did not reach statistical significance at any concentration cilostazol (p = 0.11-0.18). Diabetics (n = 53) did have statistically significantly less relaxation at every concentration of cilostazol compared to nondiabetics (n = 11, p < 0.05). All venous rings relaxed in the presence of cilostazol. Veins of nondiabetics relaxed statistically significantly more than those of diabetics. Smokers had less relaxation than non-smokers, but this was not statistically significant. We are the first to demonstrate that human venous smooth muscle cells undergo relaxation when exposed to therapeutic concentrations of cilostazol.

Cilostazol and dipyridamole synergistically inhibit human platelet aggregation

It has been previously shown that cilostazol (Pletal), a drug for relief of symptoms of intermittent claudication, potently inhibits cyclic nucleotide phosphodiesterase type 3 (PDE3) and moderately inhibits adenosine uptake. It elevates extracellular adenosine concentration, by inhibiting adenosine uptake, and combines with PDE3 inhibition to augment inhibition of platelet aggregation and vasodilation while attenuating positive chronotropic and inotropic effects on the heart. In the present study, we tested the hypothesis that cilostazol combined with a more potent adenosine uptake inhibitor, dipyridamole, synergistically inhibited platelet aggregation in human blood. In the presence of exogenous adenosine (1 microM), the combination of cilostazol and dipyridamole synergistically increased intra-platelet cAMP. Furthermore, cilostazol inhibited platelet aggregation in a washed platelet assay concentration-dependently with IC50s of 0.17 +/- 0.04 microM (P < 0.05 versus plus adenosine alone of 0.38 +/- 0.05 microM), 0.11 +/- 0.06 microM (P < 0.05), and 0.01 +/- 0.01 microM (P < 0.005) when combined with 1, 3, or 10 microM dipyridamole, respectively (n = 5). In whole blood, cilostazol (0.3 to 3 microM) and dipyridamole (1 or 3 microM) synergistically inhibited collagen- and ADP-induced platelet aggregation in vitro. Furthermore, the synergism was confirmed in an open-label, sequential study in healthy human subjects using ex vivo whole-blood collagen-induced platelet aggregation. Four hours after oral co-administration of cilostazol (100 mg) and dipyridamole (200 mg), platelet aggregation was inhibited by 45 +/- 17%, while no significant inhibition was observed from subjects treated with either drug alone. The combination may provide a potential treatment of arterial thrombotic disorders.

Effect of remnant-like particle on shear-induced platelet activation and its inhibition by antiplatelet agents

Remnant-like particles (RLPs) have been reported to promote atherosclerosis and to have effects on platelet function. We studied the effects of RLP on shear-induced platelet activation and their inhibition by antiplatelet agents in vitro. RLP were separated using two monoclonal antibodies, anti apo B-100 and anti apo A-I. These RLP fractions were added to whole blood (WB) or platelet-rich plasma (PRP) in serial dilution of 1, 10 or 100 microg RLP triglyceride (TG) per ml of total sample volume. These samples were incubated, and then stimulated with a high shear stress of 108 dyn/cm(2). Shear-induced platelet aggregation (SIPA) was calculated from the percentage of single platelet loss. P-selectin expression on platelet surface and platelet-derived microparticle (PMP) generation were measured before and after stimulation with shear stress using flow cytometer. SIPA was significantly enhanced by RLP in WB but not in PRP. This enhancing effect was not dose-dependent and was greatest at 10 microg TG/ml. P-selectin expression induced by shear stress was only enhanced by RLP at a concentration of 100 microg TG/ml in both WB and PRP, while generation of PMP induced by shear stress was only enhanced by RLP at a concentration of 100 microg TG/ml in WB. Aspirin inhibited only the enhancement of SIPA by RLPs, while cilostazol inhibited the enhancement of not only SIPA but also p-selectin expression and PMP generation by RLPs.

Comparison of cilostazol and clopidogrel after successful coronary stenting

This study compared the safety and efficacy of cilostazol and clopidogrel after coronary stenting. Patients (n = 689) who underwent successful stenting were randomly assigned to receive cilostazol (group 1, n = 344, 612 lesions) or clopidogrel (group 2, n = 345, 628 lesions). The incidence of subacute stent thrombosis or major adverse cardiac events, including death, myocardial infarction, and target lesion revascularization within 30 days (2.6% in group 1 vs 2.0% in group 2, p = 0.61) and side effects that required cessation of study drug (0.6% each) did not differ statistically between groups. These results indicate that cilostazol is as safe and effective as clopidogrel in preventing thrombotic complications after stenting.

Cilostazol prevents the progression of the symptomatic intracranial arterial stenosis: the multicenter double-blind placebo-controlled trial of cilostazol in symptomatic intracranial arterial stenosis

BACKGROUND AND PURPOSE

Cilostazol, a phosphodiesterase inhibitor, has been reported to reduce restenosis rate after coronary angioplasty and stenting. This study was performed to investigate the effect of cilostazol on the progression of intracranial arterial stenosis (IAS).

METHODS

We randomized 135 patients with acute symptomatic stenosis in the M1 segment of middle cerebral artery or the basilar artery to either cilostazol 200 mg per day or placebo for 6 months. Aspirin 100 mg per day was also given to all patients. Patients with potential embolic sources in the heart or extracranial arteries were excluded. IAS was assessed by magnetic resonance angiogram (MRA) and transcranial Doppler (TCD) at the time of recruitment and 6 months later. The primary outcome was the progression of symptomatic IAS on MRA and secondary outcomes were clinical events and progression on TCD.

RESULTS

Thirty-eight patients were prematurely terminated. Dropout rates and reasons for dropouts were similar between the cilostazol and placebo groups. There was no stroke recurrence in either cilostazol or placebo group, but there was 1 death and 2 coronary events in each group. In cilostazol group, 3 (6.7%) of 45 symptomatic IAS progressed and 11 (24.4%) regressed. In placebo group, 15 (28.8%) of symptomatic IAS progressed and 8 (15.4%) regressed. Progression of symptomatic IAS in cilostazol group was significantly lower than that in placebo group (P=0.008)

CONCLUSIONS

Our study suggests that symptomatic IAS is a dynamic lesion and cilostazol may prevent its progression.

Clinical Characteristics, Risk Factors, and Medical Treatment of 561 Patients With Peripheral Arterial Disease Followed in an Academic Vascular Surgery Clinic

The charts of all 561 patients (69% men and 31% women, mean age 71 +/- 10 years) with peripheral arterial disease (PAD) followed in an academic vascular surgery clinic were reviewed. Coexistent coronary artery disease (CAD) was present in 364 of 561 patients (65%). Of the 561 patients with PAD, 442 (79%) were current or exsmokers, 385 (69%) had hypertension, 225 (40%) had diabetes, 358 (64%) had a serum low-density lipoprotein (LDL) cholesterol > or =100 mg/dL, and 228 (41%) had a serum high-density lipoprotein cholesterol <40 mg/dL. Cilostazol or pentoxifylline was given to 301 of 301 patients (100%) with intermittent claudication. Aspirin or clopidogrel was given to 501 of 561 patients (89%) with PAD. Statins were given to 282 of 358 patients (79%) with PAD and an increased serum LDL cholesterol. If CAD was present, beta blockers were given to 301 of 364 patients (83%) and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers to 303 of 364 patients (83%).

Effects of cilostazol on lipid and fatty acid metabolism

Cilostazol is a selective inhibitor of phosphodiesterase III with anti-platelet-aggregatory and vasodilating properties. Randomised, double-blind, placebo-controlled trials in 2702 patients with intermittent claudication demonstrated that cilostazol significantly increased walking distances compared with placebo. Furthermore, the agent has beneficial effects on the serum lipid profile and fatty acid composition in plasma. Consequently, cilostazol may be useful to prevent atherosclerosis from progressing by ameliorating lipid and fatty acid metabolism.

Cilostazol Reduces Atherosclerosis by Inhibition of Superoxide and Tumor Necrosis Factor-α Formation in Low-Density Lipoprotein Receptor-Null Mice Fed High Cholesterol

This study shows that 6-[4-(1-cyclohexyl-1H-tetrazol-5-yl) butoxy]-3,4-dihydro-2(1H)-quinolinone (cilostazol) suppresses the atherosclerotic lesion formation in the low-density lipoprotein receptor (Ldlr)-null mice. Ldlr-null mice fed a high cholesterol diet showed multiple plaque lesions in the proximal ascending aorta including aortic sinus, accompanied by increased macrophage accumulation with increased expression of vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1). Supplementation of cilostazol (0.2% w/w) in diet significantly decreased the plaque lesions with reduced macrophage accumulation and suppression of VCAM-1 and MCP-1 in situ. Increased superoxide and tumor necrosis factor-alpha (TNF-alpha) production were significantly lowered by cilostazol in situ as well as in cultured human umbilical vein endothelial cells (HUVECs). TNF-alpha-induced increased inhibitory kappaBalpha degradation in the cytoplasm and nuclear factor-kappaB (NF-kappaB) p65 activation in the nuclei of HUVECs were reversed by cilostazol (1 approximately 100 microM) as well as by (E)-3[(4-t-butylphenyl)sulfonyl]-2-propenenitrile (BAY 11-7085) (10 microM), suggesting that cilostazol strongly inhibits NF-kappaB activation and p65 translocation into the nuclei. Furthermore, in gel shift and DNA-binding assay, cilostazol inhibited NF-kappaB/DNA complex and nuclear DNA-binding activity of the NF-kappaB in the nuclear extracts of the RAW 264.7 cells. Taken together, it is suggested that the anti-atherogenic effect of cilostazol in cholesterol-fed Ldlr-null mice is ascribed to its property to suppress superoxide and TNF-alpha formation, and thereby reducing NF-kappaB activation/transcription, VCAM-1/MCP-1 expressions, and monocyte recruitments.

Cilostazol inhibits vascular smooth muscle cell growth by downregulation of the transcription factor E2F

Neointimal formation, the leading cause of restenosis, is caused by proliferation of vascular smooth muscle cells (VSMCs). Patients with diabetes mellitus have higher restenosis rates after coronary angioplasty than nondiabetic patients. Cilostazol, a selective type 3 phosphodiesterase inhibitor, is currently used to treat patients with diabetic vascular complications. Cilostazol is a potent antiplatelet agent that inhibits VSMC proliferation. In the present study, we examine whether the antiproliferative effect of cilostazol on VSMCs is mediated by inhibition of an important cell cycle transcription factor, E2F. Cilostazol inhibited the proliferation of human VSMCs in response to high glucose in vitro and virtually abolished neointimal formation in rats subjected to carotid artery injury in vivo. Moreover, the compound suppressed high-glucose-induced E2F-DNA binding activity, and the expression of E2F1, E2F2, cyclin A, and PCNA proteins. These data suggest that the beneficial effects of cilostazol on high-glucose-stimulated proliferation of VSMCs are mediated by the downregulation of E2F activity and expression of its downstream target genes, including E2F1, E2F2, cyclin A, and PCNA.

Inhibitory actions of cilostazol on electrical responses of smooth muscle isolated from the guinea-pig stomach antrum

We have investigated the effects of cilostazol, a type III phosphodiesterase inhibitor, on the electrical responses of smooth muscle tissue isolated from the guinea-pig stomach antrum. Cilostazol (10(-5) M) inhibited slow waves recorded from circular muscle cells, but did not significantly alter the pacemaker potentials and follower potentials recorded from myenteric interstitial cells and longitudinal muscle cells respectively. Slow potentials generated in isolated circular muscle bundles without attached myenteric interstitial cells were inhibited by cilostazol (>10(-7) M), while all membrane activities were abolished by 10(-5) M cilostazol. In circular muscle bundles, the input resistance of smooth muscle cells and the refractory period for the generation of slow potentials were not altered during the inhibition of spontaneous activity with cilostazol. While cilostazol at 10(-7) and 10(-6) M did not elevate the tissue content of cyclic AMP, at 10(-5) M cyclic AMP was elevated by about 30%. A similar elevation was also produced by 10(-7) M forskolin. The content of cyclic AMP was not significantly increased in preparations stimulated with 10(-3) M caffeine. The potency for inhibiting slow waves was in the order caffeine (10(-3) M) > forskolin (10(-7) M) > cilostazol (10(-5) M). The frequency of slow waves was decreased by caffeine or forskolin but not by cilostazol, while the duration was reduced by caffeine but not by cilostazol or forskolin. Follower potentials were modulated by caffeine and forskolin, but not by cilostazol: the duration was reduced by caffeine, the frequency was reduced by caffeine or forskolin, and the amplitude was not significantly altered by any of them. The results indicate that cilostazol has high selectivity in inhibiting the activity of circular muscle much more than that of longitudinal muscle or pacemaker cells, with no causal relation to the tissue content of cyclic AMP as appears to be the case for the inhibitory actions of caffeine and forskolin.

Cilostazol inhibits platelet-leukocyte interaction by suppression of platelet activation

The influence of three anti-platelet drugs, cilostazol, aspirin, and tirofiban, was investigated on platelet-leukocyte interaction by flow cytometry. When platelets and leukocytes were pre-incubated with anti-platelet drugs and stimulated by thrombin or collagen, cilostazol was found to inhibit platelet adhesion to monocytes and polymorphonuclear cells (PMNs). Similar effects were observed with anti-CD62P antibody, while aspirin and tirofiban did not appear to interfere with interaction between platelets and leukocytes. In the platelets pre-incubated with anti-platelet drugs, cilostazol significantly reduced CD62P expression and GPIIb/IIIa activation on platelet surface stimulated by thrombin or collagen. Aspirin inhibited CD62P expression and GPIIb/IIIa activation induced by collagen, but not thrombin. Tirofiban significantly blocked GPIIb/IIIa activation induced with both, and weakly inhibited CD62P expression induced by collagen. When added after stimulation of platelets, cilostazol again significantly inhibited CD62P expression and GPIIb/IIIa activation, although to a lesser extent than in the pre-incubation study. Aspirin hardly inhibited CD62P expression or GPIIb/IIIa activation, while tirofiban strongly blocked GPIIb/IIIa activation induced by thrombin or collagen, but had little effects on CD62P expression. In conclusion, our results suggest that cilostazol inhibits platelet-leukocyte interaction by reducing CD62P expression on the platelet surface.