Addition of cilostazol to aspirin and a thienopyridine for prevention of restenosis after coronary artery stenting: a meta-analysis

A Systematic Review and Meta-Analysis of Efficacy and Safety of Cilostazol Prescription in Patients With Femoropopliteal Peripheral Artery Disease After Endovascular Therapy

PURPOSE

The purpose of this study is to assess the efficacy and safety of cilostazol prescription in patients with femoropopliteal peripheral artery disease (PAD) after endovascular therapy (EVT).

MATERIALS AND METHODS

We conducted a systematic review and meta-analysis of all studies reporting the outcomes of cilostazol after femoropopliteal EVT of PAD up to September 2022. Clinical outcomes of interest included primary patency, in-stent restenosis (ISR), vessel re-occlusion, freedom from target lesion revascularization (TLR), repeat revascularization, all-cause mortality, amputation, major adverse cardiovascular events (MACEs) and major adverse limb events (MALEs), and bleeding complication.

RESULTS

A total of 4 randomized controlled trials (RCTs) and 8 observational studies containing a total of 4898 patients met the inclusion criteria and were included in this systematic review and meta-analysis. We found that the use of cilostazol was associated with higher primary patency after femoropopliteal artery EVT (odds ratio [OR]=1.67, 95% confidence interval [CI]=1.50-1.87, p<0.001, I2=33.2%), a lower risk of ISR (OR=0.43, 95% CI=0.29-0.63, p<0.001, I2=37.6%), repeat revascularization (OR=0.43, 95% CI=0.24-0.76, p<0.005, I2=27.4%), and vessel re-occlusion (OR=0.59, 95% CI=0.38-0.93, p<0.05, I2=0%). There was an increase in freedom from TLR rate (OR=2.19, 95% CI=1.58-3.05, p<0.001, I2=0%), as well as a reduction in the occurrence of MALEs (OR=0.50, 95% CI=0.29-0.85, p<0.05, I2=0%). However, there was no significant difference in amputation, MACEs, all-cause mortality, and major bleeding complications. Subgroup analysis showed that cilostazol treatment in patients with femoropopliteal drug-eluting stents (DES) implantation remained associated with higher primary patency and a lower risk of ISR.

CONCLUSIONS

After EVT of femoropopliteal artery lesions, additional oral cilostazol enhances primary patency, reduces the occurrences of ISR and vessel re-occlusion, diminishes the risks associated with MALEs, lowers the need for repeat revascularization, and increases freedom from TLR rates. However, it does not impact amputation, MACEs, all-cause mortality, or major bleeding complications. These findings suggest cilostazol as a potentially safe and effective adjunct therapy in patients with femoropopliteal PAD after EVT.

CLINICAL IMPACT

After undergoing endovascular therapy (EVT) for femoropopliteal artery lesions, the addition of cilostazol to antiplatelet therapy can significantly improve primary patency, reducing the incidence of in-stent restenosis, repeat revascularization, vessel re-occlusion, and major adverse limb events while increasing freedom from target lesion revascularization rate. The simultaneous use of drug-eluting stents in the femoropopliteal artery lesions, combined with cilostazol, potentially results in a synergistic anti-stenotic effect. This therapeutic approach does not appear to be associated with an increased risk of major bleeding events or all-cause mortality. These findings provide additional evidence supporting the treatment of anti-stenosis in patients with femoropopliteal artery lesions after EVT.

Predicting and Analyzing Restenosis Risk after Endovascular Treatment in Lower Extremity Arterial Disease: Development and Assessment of a Predictive Nomogram

PURPOSE

This study aimed to develop and internally validate nomograms for predicting restenosis after endovascular treatment of lower extremity arterial diseases.

MATERIALS AND METHODS

A total of 181 hospitalized patients with lower extremity arterial disease diagnosed for the first time between 2018 and 2019 were retrospectively collected. Patients were randomly divided into a primary cohort (n=127) and a validation cohort (n=54) at a ratio of 7:3. The least absolute shrinkage and selection operator (LASSO) regression was used to optimize the feature selection of the prediction model. Combined with the best characteristics of LASSO regression, the prediction model was established by multivariate Cox regression analysis. The predictive models' identification, calibration, and clinical practicability were evaluated by the C index, calibration curve, and decision curve. The prognosis of patients with different grades was compared by survival analysis. Internal validation of the model used data from the validation cohort.

RESULTS

The predictive factors included in the nomogram were lesion site, use of antiplatelet drugs, application of drug coating technology, calibration, coronary heart disease, and international normalized ratio (INR). The prediction model demonstrated good calibration ability, and the C index was 0.762 (95% confidence interval: 0.691-0.823). The C index of the validation cohort was 0.864 (95% confidence interval: 0.801-0.927), which also showed good calibration ability. The decision curve shows that when the threshold probability of the prediction model is more significant than 2.5%, the patients benefit significantly from our prediction model, and the maximum net benefit rate is 30.9%. Patients were graded according to the nomogram. Survival analysis found that there was a significant difference in the postoperative primary patency rate between patients of different classifications (log-rank p<0.001) in both the primary cohort and the validation cohort.

CONCLUSION

We developed a nomogram to predict the risk of target vessel restenosis after endovascular treatment by considering information on lesion site, postoperative antiplatelet drugs, calcification, coronary heart disease, drug coating technology, and INR.

CLINICAL IMPACT

Clinicians can grade patients after endovascular procedure according to the scores of the nomograms and apply intervention measures of different intensities for people at different risk levels. During the follow-up process, an individualized follow-up plan can be further formulated according to the risk classification. Identifying and analyzing risk factors is essential for making appropriate clinical decisions to prevent restenosis.

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.

Stroke thrombectomy complication management

Endovascular mechanical thrombectomy (EVT) is widely accepted as the first-line treatment for acute ischemic stroke in patients with large vessel occlusion. Being an invasive treatment, this method is associated with various preoperative, perioperative, and postoperative complications. These complications may influence peri-interventional morbidity and mortality and therefore treatment efficacy and clinical outcome. The aim of this review is to discuss the most common types of complications associated with EVT, the probable mechanisms of injury, and effective methods to manage and prevent complications.

Clinical trial of carotid artery stenting using dual-layer CASPER stent for carotid endarterectomy in patients at high and normal risk in the Japanese population

BACKGROUND

The dual-layer nitinol CASPER stent was designed to prevent plaque prolapse into its strut and periprocedural stroke.

OBJECTIVE

To conduct a clinical trial for government approval of the device in patients at either high or normal risk for carotid endarterectomy (CEA).

METHODS

Eligible patients had ≥50% symptomatic stenosis or ≥80% asymptomatic stenosis according to the North American Symptomatic Carotid Endarterectomy Trial methods (peak systolic velocity 130 and 230 cm/s on ultrasonography, respectively). The primary endpoint was the lack of major adverse events (MAEs), defined as death, stroke, and myocardial infarction within 30 days, and ipsilateral stroke within 1 year. The performance goal was set at 90.5%. MAE rates were also compared between the CEA high- and normal-risk groups.

RESULTS

140 carotid artery stenting procedures, including 40% of patients at high risk and 60% at normal risk for CEA, were performed in 13 institutes. MAEs occurred in two cases (one intraprocedural and one postprocedural stroke), and the MAE rate was 1.4%. The non-MAE rate was 98.6% according to Kaplan-Meier analysis, which was superior to the previously set performance goal. The deployment success, target lesion revascularization (TLR), in-stent restenosis, and cerebrovascular event rates were 99.3%, 2.4%, 8.5%, and 7.2%, respectively. The MAE rate in patients with normal CEA risk was 1.2%, which was similar to the high-risk CEA group, with no significant difference due to the small number of MAEs.

CONCLUSIONS

The MAE rate following use of the CASPER stent was low (1.4%). The MAE, deployment success, TLR, in-stenosis, and cerebrovascular event rates were similar to those of previous reports.

Literature review and meta-analysis of the efficacy of cilostazol on limb salvage rates after infrainguinal endovascular and open revascularization

BACKGROUND

Current clinical guidelines recommend the use of cilostazol in the treatment of patients with infrainguinal peripheral artery disease (PAD) who experience intermittent claudication. However, the role of cilostazol therapy in patients with advanced PAD and critical limb ischemia (CLI) remains unclear. To conduct a meta-analysis of randomized controlled trials and cohort studies that evaluated the effect of cilostazol vs standard antiplatelet therapy on limb-related and arterial patency-related outcomes. We also reviewed literature pertinent to the effect of cilostazol on wound healing in patients with advanced PAD.

METHODS

We performed a MEDLINE, EMBASE, COCHRANE (CENTRAL), SCOPUS, and US Clinical Trials database search for all trials and studies since 1999 that compared cilostazol with standard antiplatelet therapy in the setting of infrainguinal PAD revascularization procedures (endovascular or open). Aggregate data was collected from four randomized control trials and six retrospective cohort studies. The end point incidence ratios and treatment effects were generated from each study and reported as hazard ratios (HR) using a random-effect model. We also reviewed 10 studies that evaluated the effect of cilostazol on wound healing in patients with advanced PAD.

RESULTS

From more than 25,000 total patients, 3136 patients met our inclusion criteria. All patients had at least lifestyle-impacting intermittent claudication, and more than 50% met the definition of CLI (Rutherford class ≥4). Patient age range was 53 to 83 years, and the majority were male (66%). The mean follow-up time averaged 2 years across all studies. Meta-analysis revealed that cilostazol treatment favored amputation-free survival (hazard ratio [HR], 0.79; 95% confidence interval [CI], 0.69-0.91), limb salvage rate (HR, 0.42; 95% CI, 0.27-0.66), decreased repeat revascularization (risk ratio [RR], 0.44; 95% CI, 0.37-0.52), and decreased restenosis (RR, 0.68; 95% CI, 0.61-0.76). Cilostazol treatment also increased freedom from target lesion revascularization (RR, 1.35; 95% CI, 1.21-1.53) with no difference in all-cause mortality. Effective wound healing was found to be an inconsistent outcome measure in patients receiving cilostazol therapy.

CONCLUSIONS

We observed that cilostazol therapy has a beneficial impact on all limb-related and arterial patency-related outcomes, but no effect on all-cause mortality in patients with advanced PAD and CLI undergoing revascularization procedures. Additional studies are needed to evaluate the effect of cilostazol therapy on wound healing in patients with advanced PAD.

Phosphodiesterase Inhibitors: Could They Be Beneficial for the Treatment of COVID-19?

In March 2020, the World Health Organization declared the severe acute respiratory syndrome corona virus 2 (SARS-CoV2) infection to be a pandemic disease. SARS-CoV2 was first identified in China and, despite the restrictive measures adopted, the epidemic has spread globally, becoming a pandemic in a very short time. Though there is growing knowledge of the SARS-CoV2 infection and its clinical manifestations, an effective cure to limit its acute symptoms and its severe complications has not yet been found. Given the worldwide health and economic emergency issues accompanying this pandemic, there is an absolute urgency to identify effective treatments and reduce the post infection outcomes. In this context, phosphodiesterases (PDEs), evolutionarily conserved cyclic nucleotide (cAMP/cGMP) hydrolyzing enzymes, could emerge as new potential targets. Given their extended distribution and modulating role in nearly all organs and cellular environments, a large number of drugs (PDE inhibitors) have been developed to control the specific functions of each PDE family. These PDE inhibitors have already been used in the treatment of pathologies that show clinical signs and symptoms completely or partially overlapping with post-COVID-19 conditions (e.g., thrombosis, inflammation, fibrosis), while new PDE-selective or pan-selective inhibitors are currently under study. This review discusses the state of the art of the different pathologies currently treated with phosphodiesterase inhibitors, highlighting the numerous similarities with the disorders linked to SARS-CoV2 infection, to support the hypothesis that PDE inhibitors, alone or in combination with other drugs, could be beneficial for the treatment of COVID-19.

Clinical efficacy and safety of cilostazol: a critical review of the literature

Cilostazol is a unique antiplatelet agent that has been commercially available for over two decades. As a phosphodiesterase III inhibitor, it reversibly inhibits platelet aggregation yet also possesses vasodilatory and antiproliferative properties. It has been widely studied in a variety of disease states, including peripheral arterial disease, cerebrovascular disease, and coronary artery disease with percutaneous coronary intervention. Overall, cilostazol appears to be a promising agent in the management of these disease states with a bleeding profile comparable to placebo; even when combined with other antiplatelet agents, cilostazol does not appear to increase the rate of bleeding. Despite the possible benefit of cilostazol, its use is limited by tolerability as some patients often report drug discontinuation due to headache, diarrhea, dizziness, or increased heart rate. To date, it has been predominantly studied in the Asian population, making it difficult to extrapolate these results to a more diverse patient population. This paper discusses the evolving role of cilostazol in the treatment of vascular diseases.

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.

Addition of cilostazol to conventional dual antiplatelet therapy reduces the risk of cardiac events and restenosis after drug-eluting stent implantation: a meta-analysis

This meta-analysis was performed to compare the risk of cardiac events and restenosis between triple antiplatelet therapy (TAT, addition of cilostazol to aspirin and clopidogrel) and conventional dual antiplatelet therapy (DAT, aspirin and clopidogrel) in drug-eluting stents (DES) implantation patients. We performed PUBMED, MEDLINE, EMBASE, and Cochrane CENTRAL searches for randomized clinical trials of TAT versus DAT in patients after DES implantation. Five clinical trials were involved in the study. TAT was associated with a 36% reduction in major adverse cardiac events (MACE; odds ratio (OR) = 0.64; 95% confidence interval (CI) = 0.51-0.81, P < .01), a 40% reduction (OR = 0.60, 95% CI = 0.44-0.80; P < .01) in target vessel revascularization (TVR), a 44% reduction (OR = 0.56, 95% CI = 0.34-0.91; P = .02) in target lesion revascularization (TLR) and a 47%/44% reduction in in-segment/in-stent restenosis (P < .01) and lower in-segment/in-stent late loss (P < .01). As regards to the safety assessment, there was no significant difference about the risk of stent thrombosis and bleeding between TAT and DAT group, while the risk of gastrointestinal trouble was significantly higher in TAT group (OR = 2.46, 95% CI = 1.25-4.86; P < .01). Addition of cilostazol to DAT reduced the incidence of MACE, TVR, and TLR after DES implantation. TAT also reduced the risk of restenosis and late loss in patients after DES implantation.

Cilostazol prevents progression of asymptomatic carotid artery stenosis in patients with contralateral carotid artery stenting

BACKGROUND AND PURPOSE

The progression of atherosclerosis is related to various factors. Although antiplatelet therapy is used for the management of acute ischemic stroke and for the prevention of recurrent stroke, the antiplatelet agent cilostazol may also reduce restenosis after stent implantation in any vessel. This study was performed to assess the impact of cilostazol on plaque progression in the carotid artery contralateral to a stented artery.

MATERIALS AND METHODS

Ninety-five patients who underwent contralateral CAS who also had ipsilateral 0%-79% ICS were enrolled. ICS was assessed by duplex sonography every 6 months and by MR imaging/angiography, and digital subtraction angiography if necessary, every 12 months according to the NASCET method. Patient age, sex, past history, and perioperative medical conditions were recorded.

RESULTS

While 22.1% of patients experienced disease progression, symptomatic ipsilateral stroke occurred in only 1.1% of patients over 36.2 ± 18.8 months. On multivariate analysis, precarotid stenosis (HR per 10% increase, 2.08; 95% CI, 1.43-3.05; P < .001) and cilostazol use (HR 0.16; 95% CI, 0.03-0.85; P = .03) were independent predictors for the progression of ICS.

CONCLUSIONS

A higher degree of initial stenosis is associated with progression of asymptomatic ICS. Cilostazol may reduce the rate of disease progression in patients with asymptomatic ICS.

Cilostazol added to aspirin and clopidogrel reduces revascularization without increases in major adverse events in patients with drug-eluting stents: a meta-analysis of randomized controlled trials

BACKGROUND

The effects of cilostazol added to aspirin and clopidogrel (triple antiplatelet therapy: TAT) on clinical outcomes after drug-eluting stent (DES) implantation are unknown.

METHODS

We conducted a meta-analysis of randomized controlled trials (RCTs) comparing TAT with aspirin and clopidogrel (dual antiplatelet therapy: DAT) in DES patients. Clinical end points were target lesion (TLR) and/or vessel (TVR) revascularization, death, myocardial infarction (MI), stent thrombosis (ST), bleeding, rash, gastrointestinal (GI) side effects, and drug discontinuation. We calculated the pooled estimate based on a fixed-effects model using Peto odds ratio (OR) for rare events. If heterogeneity was observed across an individual RCT, an analysis based on a random-effects model was performed.

RESULTS

Eight RCTs were included in this meta-analysis, involving 3590 patients (TAT:DAT=1800:1790). Up to 24 months, TAT showed a significant reduction in TLR (OR: 0.58, 95% confidence interval (CI): 0.43 to 0.78, p<0.001) and TVR (OR: 0.58, 95% CI: 0.40 to 0.83, p=0.003) compared with DAT. The incidence of death, MI, ST, or overall or major bleeding was comparable between the 2 groups, whereas the proportion of rash (OR: 2.50, 95% CI: 1.52 to 4.10, p<0.001), GI side effects (OR: 3.14, 95% CI: 1.79 to 5.50, p<0.001), or drug discontinuation (OR: 6.81, 95% CI: 2.12 to 21.86, p<0.001) was higher in TAT than DAT.

CONCLUSIONS

In this meta-analysis, TAT was associated with significantly effective outcomes for TLR and TVR without any increase in major adverse events but was associated with tolerance issues compared with DAT after DES implantation.

Anti-platelet therapy: phosphodiesterase inhibitors

Inhibition of platelet aggregation can be achieved either by the blockade of membrane receptors or by interaction with intracellular signalling pathways. Cyclic adenosine 3',5'-monophosphate (cAMP) and cyclic guanosine 3',5'-monophosphate (cGMP) are two critical intracellular second messengers provided with strong inhibitory activity on fundamental platelet functions. Phosphodiesterases (PDEs), by catalysing the hydrolysis of cAMP and cGMP, limit the intracellular levels of cyclic nucleotides, thus regulating platelet function. The inhibition of PDEs may therefore exert a strong platelet inhibitory effect. Platelets possess three PDE isoforms (PDE2, PDE3 and PDE5), with different selectivity for cAMP and cGMP. Several nonselective or isoenzyme-selective PDE inhibitors have been developed, and some of them have entered clinical use as antiplatelet agents. This review focuses on the effect of PDE2, PDE3 and PDE5 inhibitors on platelet function and on the evidence for an antithrombotic action of some of them, and in particular of dipyridamole and cilostazol.

Targeting phosphodiesterases in anti-platelet therapy

There are two primary modes of platelet inhibition: blockade of membrane receptors or neutralization of intracellular pathways. Both means of inhibition have proven benefits in the prevention and resolution of atherothrombotic events. With regard to intracellular inhibition, phosphodiesterases (PDEs) are fundamental for platelet function. Platelets possess several PDEs (PDE2, PDE3 and PDE5) that catalyze the hydrolysis of cyclic adenosine 3'-5'-monophosphate (cAMP) and cyclic guanosine 3'-5'-monophosphate (cGMP), thereby limiting the levels of intracellular nucleotides. PDE inhibitors, such as cilostazol and dipyridamole, dampen platelet function by increasing cAMP and cGMP levels. This review focuses on the roles of PDE inhibitors in modulating platelet function, with particular attention paid to drugs that have anti-platelet clinical indications.

Restenosis after PCI. Part 2: prevention and therapy

The techniques and materials used during percutaneous coronary intervention have advanced considerably over the past 3 decades, yet restenosis remains one of the major drawbacks of this procedure. Many innovative technologies, including drug-eluting stents, with or without specific polymers, and fully biodegradable stents have been and continue to be developed in the search for a safe and effective antirestenosis therapy. Remarkable advances in stent design and nanoparticle delivery systems ('nanovehicles') have already fueled revolutionary changes in the prevention and treatment of in-stent restenosis. In this Review we provide an overview of the latest innovations for optimizing outcomes of coronary stenting, and up-to-date information about prevention and treatment of in-stent restenosis.

The role of antiplatelets in hypertension and diabetes mellitus

Cardiovascular disease (CVD) remains the main cause of mortality and morbidity in patients with diabetes. Prevention of CVD in diabetes involves a multifactorial approach that aims to treat the cluster of risk factors including hyperglycemia, dyslipidemia, obesity, hypertension, and hypercoagulation associated with this condition. Antiplatelets reduce the prothrombotic environment in diabetes, but complications of this therapeutic approach include a general risk of bleeding, specifically intracranial hemorrhage, the risk of which increases in the presence of hypertension. Current guidelines recommend the use of antiplatelet agents after tight control of blood pressure, which, in clinical practice, is not always possible. In this review, the evidence for antiplatelet use in diabetes with particular emphasis on patients with associated hypertension is examined. Safe levels of blood pressure with antiplatelet therapy, various studies, and general recommendations for diabetes patients, in light of current evidence, are explored.

Clopidogrel: a pharmacogenomic perspective on its use in coronary artery disease

The thienopyridine antiplatelet agent clopidogrel is an effective drug for the prevention of vascular events. However, data has accumulated over time to suggest it is prone to significant interpatient variability. While there are several factors that contribute to this, one of the most important is variability in forming the active metabolite necessary for clopidogrel function. Several enzymes are involved in formation of this metabolite, and two, CYP2C19 and P-glycoprotein, appear to have alleles that both occur frequently in the population and have a clinically significant impact. Patients carrying these alleles can be identified, but it remains to be determined if this information is necessary or sufficient for risk stratification. Furthermore, if patients with high-risk alleles are identified, it is unclear how treatment should be adjusted.

Prevention of the renarrowing of coronary arteries using drug-eluting stents in the perioperative period: an update

The management of patients scheduled for surgery with a coronary stent, and receiving 1 or more antiplatelet drugs, has many controversies. The premature discontinuation of antiplatelet drugs substantially increases the risk of stent thrombosis (ST), myocardial infarction, and cardiac death, and surgery under an altered platelet function could also lead to an increased risk of bleeding in the perioperative period. Because of the conflict in the recommendations, this article reviews the current antiplatelet protocols after positioning a coronary stent, the evidence of increased risk of ST associated with the withdrawal of antiplatelet drugs and increased bleeding risk associated with its maintenance, the different perioperative antiplatelet protocols when patients are scheduled for surgery or need an urgent operation, and the therapeutic options if excessive bleeding occurs.

The interaction between clopidogrel and proton pump inhibitors (PPI): is there any clinical relevance?

The potential interaction between clopidogrel and proton pump inhibitors (PPI) in patients with acute coronary syndrome (ACS) raises serious concerns for cardiologists. However, in patients on this combination of drugs, there is no conclusive evidence of an increase in adverse cardiovascular events. From pharmacologic and pharmacodynamic perspectives, there is a real interaction between clopidogrel and PPIs because of the competitive inhibition of CYP2C19 isoenzyme which is required for biotransformation of clopidogrel to its active metabolite. The consequent decrease in the availability of this active metabolite leads to attenuation of antiplatelet efficacy of clopidogrel. In several observational trials, it was shown that decreased antiplatelet effect of clopidogrel due to PPIs may translate into poor cardiovascular outcomes. However, an incomplete RCT (COGENT) and a post hoc analysis of two large trials (PRINCIPLE-TIMI 44 and TRITON-TIMI 38 trial) showed no significant adverse cardiovascular events with this combination. Caution is however needed in patients who are hypometabolizers of clopidogrel putting them at a higher risk of adverse coronary events. Since 3% of patients are likely to be hypometabolizers of clopidogrel, routine combination of clopidogrel and PPIs should be avoided. There is a heightened awareness of this interaction following multiple advisory warnings. At the same time, one should not withhold PPIs in patients who are at a high risk of developing gastrointestinal (GI) bleeding. In these patients, selected choices of PPI such as pantoprazole may be helpful and for low risk patients, serious consideration should be given to H(2) receptor antagonists or antacids. Therefore, while not compromising the cardioprotective effect of antiplatelet agents, the gastroprotective benefit of PPI should be strongly considered in patients who need both. Health care providers should remain alert to more outcome data. Future researchers will need to demonstrate the safety of coadministration of PPIs and clopidogrel and trials should be powered to detect major adverse cardiovascular events and facilitate risk stratification based on genetic polymorphism.

In-stent restenosis

The introduction of coronary stents marked a major turning point in the practice of interventional cardiology. Whereas the efficacy of balloon angioplasty was challenged both by immediate mechanical complications and by a high incidence of restenosis, coronary stents offered cardiologists a means by which to not only augment immediate procedural success, but also to reduce the incidence of restenosis following coronary intervention. However, despite technological advances and an improved understanding of the restenotic process, the overall rate of in-stent restenosis following bare metal stent implantation remains high. Although the introduction of drug-eluting stents has further reduced the incidence of restenosis, the "real-world" application of drug-eluting stents in increasingly complex lesion and patient subsets has given way to the even greater clinical challenge of managing drug-eluting stent restenosis. Although the standard treatment of bare metal stent restenosis typically involves placement of a drug-eluting stent, the optimal therapeutic approach to drug-eluting stent restenosis remains less defined. The issue of in-stent restenosis (especially following implantation of a drug-eluting stent) remains a clinical challenge, and investigation into therapeutic options remains ongoing. As technology evolves, such investigation will likely incorporate novel approaches including drug-coated balloons novel stent designs.