Twelve or 30 months of dual antiplatelet therapy after drug-eluting stents

2014 update on interventional cardiology

This article reviews the most relevant publications and studies in the field of interventional cardiology in 2014. In the area of coronary interventional procedures, integrated treatment of acute coronary syndrome continues to be the subject of numerous studies that evaluate different devices and pharmacological and mechanical strategies that can be used without increasing the risk of hemorrhage or the need for reintervention. Certain anatomical substrates continue to generate a considerable number of publications, both on the outcomes with different stents and on the use of specific techniques. Bioabsorbable drug-eluting stents are used in increasingly complex lesions with promising results. The development of interventional procedures for structural heart disease continues to advance, with new evidence on percutaneously placed aortic valve prostheses, the outcome of percutaneous mitral valve repair, and the safety and efficacy of left atrial appendage occlusion. Finally, renal denervation has generated one of the major debates of the year.

Extended duration dual antiplatelet therapy and mortality: a systematic review and meta-analysis

BACKGROUND

Treatment with aspirin and a P2Y12 inhibitor is commonly used in patients with cardiovascular disorders. The overall effect of such treatment on all-cause mortality is unknown. In the Dual Antiplatelet Therapy (DAPT) Study, continuation of dual antiplatelet therapy beyond 12 months after coronary stenting was associated with an unexpected increase in non-cardiovascular death. In view of the potential public health importance of these findings, we aimed to assess the effect of extended duration dual antiplatelet therapy on mortality by doing a meta-analysis of all randomised, controlled trials of treatment duration in various cardiovascular disorders.

METHODS

We searched Medline, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) to identify randomised controlled trials assessing the effect of extended duration versus no or short duration dual antiplatelet therapy, published before Oct 1, 2014. We did a meta-analysis to pool results with a hierarchical Bayesian random-effects model. The primary outcomes were hazard ratios comparing rates of all-cause, cardiovascular, and non-cardiovascular death.

FINDINGS

Including the DAPT Study, we identified 14 eligible trials that randomly assigned 69,644 participants to different durations of dual antiplatelet therapy. Compared with aspirin alone or short duration dual antiplatelet therapy (≤6 months), continued treatment was not associated with a difference in all-cause mortality (hazard ratio [HR] 1·05, 95% credible interval [CrI] 0·96-1·19; p=0·33). Similarly, cardiovascular (1·01, 0·93-1·12; p=0·81) and non-cardiovascular mortality (1·04, 0·90-1·26; p=0·66) were no different with extended duration versus short duration dual antiplatelet therapy or aspirin alone.

INTERPRETATION

Extended duration dual antiplatelet therapy was not associated with a difference in the risk of all-cause, cardiovascular, or non-cardiovascular death compared with aspirin alone or short duration dual antiplatelet therapy.

FUNDING

None.

Current antiplatelet agents: place in therapy and role of genetic testing

Antiplatelet therapies play a central role in reducing the risk of cardiovascular events such as myocardial infarction and stroke. While aspirin, a cyclo-oxygenase-1 inhibitor has been the cornerstone of antithrombotic treatment for several decades, P2Y12 receptor inhibitors cangrelor, clopidogrel, prasugrel, and ticagrelor and protease-activated receptor-1 antagonist vorapaxar, have emerged as additional therapies to reduce the risk of recurrent cardiovascular events in high-risk patients. Recent clinical trials evaluating the role of these agents and major society guideline updates for use of antiplatelet therapies for secondary prevention of cardiovascular events will be examined. The latest studies regarding the appropriate duration of dual antiplatelet therapy after percutaneous coronary intervention will be presented. The current state of genetic and platelet function testing will be reviewed.

Antithrombotic therapy for long-term secondary prevention of acute coronary syndrome in high-risk patients

Patients with acute coronary syndrome (ACS) represent a major clinical burden, because they tend to experience recurrent ischemic events. Acute management of patients with ACS includes combination antithrombotic therapy composed of a parenteral anticoagulant and dual-antiplatelet therapy. Dual-antiplatelet therapy is also recommended for long-term secondary prevention of ACS. Despite advances in the antithrombotic therapies available, clinical trials suggest that patients with ACS still faceã10% risk of another event within 12-15 months of the index event. Certain patient populations, such as elderly patients and those with renal impairment or heart failure, are at higher risk of recurrent ACS events, because these patients have more vascular ischemic and bleeding risk factors than most other patients. Evidence from the GRACE and CRUSADE registries suggests underuse of the guideline-recommended evidence-based therapies for the management of ACS in such patients. This review summarizes the current standard of care for patients with ACS, focusing on long-term secondary antithrombotic strategies. Registry data are used to identify high-risk patient populations; the recent antiplatelet and anticoagulant Phase III trial data are summarized to highlight any patient populations who receive greater or lesser benefit from specific long-term antithrombotic strategies. Guideline recommendations are discussed and suggestions are provided to help improve implementation of long-term secondary prevention strategies and patient prognosis after an ACS event.

Prevention of stent thrombosis: challenges and solutions

Stent thrombosis is an uncommon but serious complication which carries with it significant mortality and morbidity. This review analyzes the entity of stent thrombosis from a historical and clinical perspective, and chronicles the evolution of this condition through the various generations of stent development, from bare metal to first-generation, second-generation, and third-generation drug-eluting stents. It also delineates the specific risk factors associated with stent thrombosis and comprehensively examines the literature related to each of these risks. Finally, it highlights the preventative strategies that can be garnered from the existing data, and concludes that a multifactorial approach is necessary to combat the occurrence of stent thrombosis, with higher risk groups, such as patients with ST segment elevation myocardial infarction, meriting further research.

Contemporary Antiplatelet Strategies in the Treatment of STEMI using Primary Percutaneous Coronary Intervention

Reperfusion therapy for patients presenting with an acute ST-segment elevation myocardial infarction (STEMI) involves primary percutaneous coronary intervention (PPCI) and concomitant oral antiplatelet and intravenous antithrombotic pharmacotherapy. There is a conflict between the desire to reduce the time between first medical contact and coronary re-canalisation and achieving effective platelet inhibition with oral antiplatelet agents. This review outlines the currently available antiplatelet treatments, and their place within the therapeutic timeline of a patient presenting with STEMI. Additionally, we focus on current challenges associated with effective antiplatelet treatment, including acute stent thrombosis (AST), the effect of morphine, platelet function assessment and concomitant anticoagulant therapy.

Endothelialization of drug eluting stents and its impact on dual anti-platelet therapy duration

Coronary artery disease is a leading cause of death and disability worldwide with contemporary treatment strategies employing both optimal medical therapy and catheter based percutaneous coronary intervention (PCI) with drug eluting stents (DES). While DES have dramatically reduced restenosis rates, their use has been associated with an increased risk of late stent thrombosis and accelerated neointimal atherosclerosis (i.e. "neoatherosclerosis") both major contributors to late stent failure. The underlying substrate of late DES failure is likely related to vascular endothelial dysfunction such as poor endothelial regrowth and barrier function (i.e. "endothelial healing"). Initial concerns with 1st generation DES have lead to improvements in mechanical and biologic properties of current 2nd generation DES, which inhibit endothelial regrowth to a lesser extent, lessening late stent failure and resulting in an overall improved safety profile. Current guidelines recommend duration of at least one year of dual anti-platelet therapy with aspirin and a thienopyridine agent such as clopidogrel or prasugrel as sufficient to prevent late thrombotic complications. Recent studies, however, suggest a shorter duration of dual anti-platelet therapy may be equally as safe and efficacious in preventing stent thrombosis with newer generation DES. However, higher risk populations such as patients receiving 1st generation DES or those with increased risk for future ischemic events may benefit from a longer duration (i.e. 30 months) of DAPT to prevent major cardiovascular events with the caveat that such an approach may be associated with an increased risk for bleeding. This review examines the vascular responses to 1st and second generation DES and recent clinical trials examining DAPT duration.

Report of the American Heart Association (AHA) Scientific Sessions 2014, Chicago

The American Heart Association (AHA) Scientific Sessions were held in Chicago on November 15-19, 2014. The meeting attracted more than 17,000 participants, including physicians, research scientists, students, and paramedical personnel, from more than 100 countries. Sessions over the 5 days included comprehensive and unparalleled education delivered via more than 5,000 presentations, with 1,000 invited faculty members and 4,000 abstract presentations from world leaders in cardiovascular (CV) disease. There were 16 trials scheduled in 4 late-breaking clinical trial sessions. The Dual Antiplatelet Therapy study revealed that aspirin plus a thienopyridine beyond 1 year subsequent to placement of a drug-eluting stent, as compared with aspirin therapy alone, significantly reduced stent thrombosis and major CV and cerebrovascular events but was associated with increased risk of bleeding. The IMPROVE-IT research showed that, relative to simvastatin with placebo, simvastatin with 10 mg of ezetimibe daily led to a significantly lower primary combined endpoint in moderate- to high-risk patients, who stabilized following acute coronary syndrome. This was the first trial to demonstrate incremental clinical benefit by adding a nonstatin agent to statin therapy and reaffirmed the low-density lipoprotein (LDL) hypothesis stating that reducing LDL-cholesterol prevents CV events. Summaries and overviews of both the late-breaking trials and the sessions to which members of the Japanese Circulation Society contributed are presented.