Optimal Duration of Dual Antiplatelet Therapy after Drug-Eluting Stents: Meta-Analysis of Randomized Trials

2018 Canadian Cardiovascular Society/Canadian Association of Interventional Cardiology Focused Update of the Guidelines for the Use of Antiplatelet Therapy

Antiplatelet therapy (APT) has become an important tool in the treatment and prevention of atherosclerotic events, particularly those associated with coronary artery disease. A large evidence base has evolved regarding the relationship between APT prescription in various clinical contexts and risk/benefit relationships. The Guidelines Committee of the Canadian Cardiovascular Society and Canadian Association of Interventional Cardiology publishes regular updates of its recommendations, taking into consideration the most recent clinical evidence. The present update to the 2011 and 2013 Canadian Cardiovascular Society APT guidelines incorporates new evidence on how to optimize APT use, particularly in situations in which few to no data were previously available. The recommendations update focuses on the following primary topics: (1) the duration of dual APT (DAPT) in patients who undergo percutaneous coronary intervention (PCI) for acute coronary syndrome and non-acute coronary syndrome indications; (2) management of DAPT in patients who undergo noncardiac surgery; (3) management of DAPT in patients who undergo elective and semiurgent coronary artery bypass graft surgery; (4) when and how to switch between different oral antiplatelet therapies; and (5) management of antiplatelet and anticoagulant therapy in patients who undergo PCI. For PCI patients, we specifically analyze the particular considerations in patients with atrial fibrillation, mechanical or bioprosthetic valves (including transcatheter aortic valve replacement), venous thromboembolic disease, and established left ventricular thrombus or possible left ventricular thrombus with reduced ejection fraction after ST-segment elevation myocardial infarction. In addition to specific recommendations, we provide values and preferences and practical tips to aid the practicing clinician in the day to day use of these important agents.

Short versus prolonged dual antiplatelet therapy (DAPT) duration after coronary stent implantation: A comparison between the DAPT study and 9 other trials evaluating DAPT duration

Aims

The Dual Antiplatelet Therapy (DAPT) study demonstrated that DAPT beyond 1-year after drug-eluting stent (DES) implantation, as compared with aspirin therapy alone, significantly reduced the risk of major cardiovascular and cerebrovascular events, which was mainly driven by the large risk reduction for myocardial infarction (MI). We sought to compare the largest DAPT study with other trials evaluating DAPT durations after DES implantation.

Methods and results

By a systematic literature search, we identified 9 trials comparing prolonged- versus short-DAPT in addition to the DAPT study. The result from the DAPT study (N = 9961) with public–private collaboration was different from the pooled result of the 9 other investigator-driven trials (N = 22174) in terms of the effect of prolonged-DAPT on MI (odds ratio [OR] 0.48 [95%CI 0.38–0.62] versus pooled OR 0.88 [95%CI 0.67–1.15]: P = 0.001 for difference), while the trends for excess risk of prolonged-DAPT relative to short-DAPT for all-cause death (OR 1.31 [95%CI 0.97–1.78] versus pooled OR 1.16 [95%CI 0.92–1.45]: P = 0.53 for difference), and bleeding (OR 1.62 [95%CI 1.21–2.17] versus pooled OR 2.08 [95%CI 1.51–2.84]: P = 0.25 for difference) were consistently seen in both the DAPT and other trials. The annual rate of MI during aspirin mono-therapy in the DAPT study was much higher than that those in the other trials (2.7% versus 0.6–1.6%).

Conclusions

Given the difference between the DAPT study and other trials, future studies should focus on certain subgroups of patients that are more or less likely to benefit from longer duration DAPT.

Duration of dual antiplatelet therapy in patients treated with percutaneous coronary intervention for coronary chronic total occlusion

Background

The duration of dual antiplatelet therapy (DAPT) after drug-eluting stent implantation in coronary chronic total occlusion (CTO) remains unclear.

Methods

We retrospectively analyzed a total of 512 patients treated with percutaneous coronary intervention (PCI) in the Samsung Medical Center CTO registry. Patients were separated into ≤ 12-month (199, 38.9%) vs. > 12 month (313, 61.1%) based on DAPT duration with aspirin and clopidogrel. The primary outcome was major adverse cardiac and cerebrovascular event (MACCE) during follow-up.

Results

Median follow-up duration was 67 (interquartile range: 51–84) months. MACCE occurred in 43 patients (21.6%) in the ≤ 12-month and 55 patients (17.6%) in the > 12-month groups. In the propensity-matched population, the rate of MACCE did not differ significantly between the ≤ 12-month and > 12-month group (19.4% vs. 18.8%; hazard ratio [HR], 0.95; 95% confidential interval [CI], 0.52–1.76, p = 0.88). Moreover, moderate or severe bleeding according to BARC criteria (type 2, 3 or 5) was also similar between the ≤ 12-month and > 12-month group (2.5% vs. 1.9%; HR, 1.00; 95% CI, 0.20–4.96, p = 0.99).

Conclusion

Among patients treated with PCI for CTO, DAPT with durations of ≤ 12-month showed similar long-term clinical outcomes compared to > 12-month DAPT.

Assessment of vascular response to BiOSS LIM C® stents vs Orsiro® stents in the porcine coronary artery model

AIMS

The optimal treatment strategy for coronary bifurcation lesions is still unknown. The aim of the study was to assess applicability of the new cobalt-chromium version of the sirolimus-eluting dedicated bifurcation BiOSS^® LIM C stent in comparison with regular sirolimus-eluting Orsiro^®  stent in a porcine coronary model.

METHODS

A total of 13 BiOSS^® LIM C stents and 6 Orsiro^® stents were implanted in normal nonatherosclerotic porcine straight coronary arteries of six animals using 1.2:1.0 stent-to-artery ratio. Stent geometry and morphology were evaluated by Faxitron imaging. Vascular response was assessed by quantitative coronary angiography (QCA), optical coherence tomography (OCT), and histological analyses.

RESULTS

OCT performed at 28 days confirmed that all stents were patent with no signs of thrombus. In morphometric analysis, no differences between groups regarding stent diameter (P=.141), neointima area (P=.247), % area stenosis (P=.293), or % diameter stenosis (P=.069) were observed. Also, no significant differences were noted between groups regarding their histopathology scores. The injury and inflammation scores were low (mean grade<1) in all groups.

CONCLUSIONS

The novel BiOSS^® LIM C stent demonstrates good short-term vascular effects in a porcine coronary bifurcation model which are comparable with Orsiro^® stents.

Organ transplantation and drug eluting stents: Perioperative challenges

Patients listed for organ transplant frequently have severe coronary artery disease (CAD), which may be treated with drug eluting stents (DES). Everolimus and zotarolimus eluting stents are commonly used. Newer generation biolimus and novolimus eluting biodegradable stents are becoming increasingly popular. Patients undergoing transplant surgery soon after the placement of DES are at increased risk of stent thrombosis (ST) in the perioperative period. Dual antiplatelet therapy (DAPT) with aspirin and a P2Y12 inhibitor such as clopidogrel, prasugrel and ticagrelor is instated post stenting to decrease the incident of ST. Cangrelor has recently been approved by Food and Drug Administration and can be used as a bridging antiplatelet drug. The risk of ischemia vs bleeding must be considered when discontinuing or continuing DAPT for surgery. Though living donor transplant surgery is an elective procedure and can be optimally timed, cadaveric organ availability is unpredictable, therefore, discontinuation of antiplatelet medication cannot be optimally timed. The type of stent and timing of transplant surgery can be of utmost importance. Many platelet function point of care tests such as Light Transmittance Aggregrometry, Thromboelastography Platelet Mapping, VerifyNow, Multiple Electrode Aggregrometry are used to assess bleeding risk and guide perioperative platelet transfusion. Response to allogenic platelet transfusion to control severe intraoperative bleeding may differ with the antiplatelet drug. In stent thrombosis is an emergency where management with either a drug eluting balloon or a DES has shown superior outcomes. Post-transplant complications often involved stenosis of an important vessel that may need revascularization. DES are now used for endovascular interventions for transplant orthotropic heart CAD, hepatic artery stenosis post liver transplantation, transplant renal artery stenosis following kidney transplantation, etc. Several antiproliferative drugs used in the DES are inhibitors of mammalian target of rapamycin. Thus they are used for post-transplant immunosuppression to prevent acute rejection in recipients with heart, liver, lung and kidney transplantation. This article describes in detail the various perioperative challenges encountered in organ transplantation surgery and patients with drug eluting stents.

Bioresorbable scaffold - A magic bullet for the treatment of coronary artery disease?

Today, drug-eluting metal stents are considered the gold standard for interventional treatment of coronary artery disease. While providing inhibition of neointimal hyperplasia, drug-eluting metal stents have many limitations such as the risk of late and very late stent thrombosis, restriction of vascular vasomotion and chronic local inflammatory reaction due to permanent implantation of a 'metallic cage', recognized as a foreign body. Bioresorbable scaffold stents (BRS) are a new solution, which is trying to overcome the limitation of the 'metallic cage'. This structure provides short-term scaffolding of the vessel and then disappears, leaving nothing behind. The purpose of this review is to present the theoretical rationale for the use of BRS and to outline the clinical outcomes associated with their use in terms of data obtained from RCTs, clinical trials, registries and real life use. We have also tried to answer all questions on this intervention based on available data, with a focus on ABSORB BVS (Abbott Vascular, Santa Clara, USA). We consider that this new technology can be the "magic bullet" to treat coronary artery disease.

The Importance of the Mean Platelet Aggregation Degree in Long-term Dual Antiplatelet Therapy Following Drug-Eluting Stent Implantation

INTRODUCTION

The dual antiplatelet therapy (DAPT) and the response of clopidogrel were two pivotal issues in drug-eluting stent (DES) era.

AIMS

To analyze the combined impacts of DAPT and the response to clopidogrel to evaluate their long-term effect on patients undergoing DES implantation.

METHODS

Platelet aggregation was serially measured by light transmission aggregometry in all eligible patients during the course of treatment with DAPT, and the mean platelet aggregation degree of each participant was calculated. Based on the duration of DAPT and the mean platelet aggregation degree, all the enrolled patients were then divided into four groups. The primary endpoint was a composite of major adverse cardiovascular events.

RESULTS

We analyzed 1245 suitable patients in this study. They were divided into four groups: Group A (12-month DAPT & low platelet aggregation degree) with 233 subjects, Group B (12-month DAPT & high platelet aggregation degree) with 260 subjects, Group C (>12-month DAPT & low platelet aggregation degree) with 374 subjects, and Group D (>12-month DAPT & high platelet aggregation degree) with 378 subjects. Group C was associated with a decreased incidence of primary endpoints [HR 0.512, 95%CI (0.27-0.97); P = 0.040]. The Cox proportional hazard model was further analyzed with Groups A and B combined as the reference category [HR for Group C vs. Group A, 0.84, 95%CI (0.33-2.15); P = 0.719; HR for Group C vs. Group B, 0.45, 95%CI (0.21-0.98); P = 0.043]. Their respective multivariate Cox proportional hazard regressions confirmed these trends.

CONCLUSIONS

The mean platelet aggregation degree is of importance in long-term use of DAPT; extension of DAPT beyond 1 year should be implemented cautiously in patients implanted with DESs.