Randomised, double-blind trial on the value of tapered discontinuation of clopidogrel maintenance therapy after drug-eluting stent implantation. Intracoronary Stenting and Antithrombotic Regimen: CAUTION in Discontinuing Clopidogrel Therapy--ISAR-CAUTION

Meta-analysis Comparing Outcomes of Type 2 Myocardial Infarction and Type 1 Myocardial Infarction With a Focus on Dual Antiplatelet Therapy

BACKGROUND

There are important knowledge gaps in type 2 myocardial infarction (T2MI). Our primary objective was to compare the outcomes of patients with T2MI with those of patients with type 1 myocardial infarction (T1MI). Our secondary objective was to determine whether randomized controlled trials (RCTs) evaluating dual antiplatelets (DAPTs) have explicitly included patients with T2MI.

METHODS

We performed a meta-analysis comparing outcomes of patients with T2MI with patients with T1MI and a separate systematic review to evaluate the inclusion of T2MI in RCTs evaluating DAPT. There were 19 cohorts enrolling 48,829 patients (40,604 with T1MI and 5361 with T2MI) and 51 RCTs enrolling 188,132 patients with acute coronary syndrome.

RESULTS

Patients with T2MI had approximately 2-fold increases in unadjusted odds of long-term mortality compared with patients with T1MI (odds ratio, 2.47; 95% confidence interval, 2.06-2.96; P < 0.0001) and a 45% increase in adjusted odds of long-term mortality (odds ratio, 1.45; 95% confidence interval, 1.25-1.69; P < 0.0001, respectively). There was no published evaluation of efficacy, effectiveness, and safety of DAPT in patients with T2MI.

CONCLUSION

Patients with T2MI are at increased risk of adjusted all-cause long-term mortality compared with patients with T1MI. The role of DAPT remains unclear in T2MI.

Platelets, inflammation and anti-inflammatory effects of antiplatelet drugs in ACS and CAD

Platelets play a pivotal role in chronic inflammation leading to progression of atherosclerosis and acute coronary events. Recent discoveries on novel mechanisms and platelet-dependent inflammatory targets underpin the role of platelets to maintain a chronic inflammatory condition in cardiovascular disease. There is strong and clinically relevant crosslink between chronic inflammation and platelet activation. Antiplatelet therapy is a cornerstone in the prevention and treatment of acute cardiovascular events. The benefit of antiplatelet agents has mainly been attributed to their direct anti-aggregatory impact. Some anti-inflammatory off-target effects have also been described. However, it is unclear whether these effects are secondary due to inhibition of platelet activation or are caused by direct distinct mechanisms interfering with inflammatory pathways. This article will highlight novel platelet associated targets that contribute to inflammation in cardiovascular disease and elucidate mechanisms by which currently available antiplatelet agents evolve anti-inflammatory capacities, in particular by carving out the differential mechanisms directly or indirectly affecting platelet mediated inflammation. It will further illustrate the prognostic impact of antiplatelet therapies by reducing inflammatory marker release in recent cardiovascular trials.

Duration of Dual Antiplatelet Therapy in Coronary Artery Disease: a Review Article

Dual antiplatelet therapy (DAPT) following an acute coronary syndrome or after placement of a coronary artery stent is superior to aspirin alone for prevention of atherothrombotic events but carries an increased bleeding risk. DAPT should be continued for at least 12 months based on current guidelines. Recent randomized trials demonstrate reduced ischemic events including myocardial infarction (MI), stroke, and death with continued DAPT for up to 30 months or longer, particularly in the post-MI population. However, this clinical benefit is accompanied by an increased risk of bleeding. Additional trials show mixed safety and efficacy with duration of DAPT of less than 12 months. The current data emphasizes the need to individualize DAPT duration at the patient level to balance the clinical benefits of a reduced risk of cardiovascular ischemic events with the greater risk of clinically significant bleeding. Patients at an increased risk of ischemic events and a lower risk of bleeding should be strongly considered for prolonged DAPT beyond the 1 year currently recommended in the practice guidelines.

Stent thrombosis and restenosis: what have we learned and where are we going? The Andreas Grüntzig Lecture ESC 2014

Modern-day stenting procedures leverage advances in pharmacotherapy and device innovation. Patients treated with contemporary antiplatelet agents, peri-procedural antithrombin therapy and new-generation drug-eluting stents (DES) have excellent outcomes over the short to medium term. Indeed, coupled with the reducing costs of these devices in most countries there remain very few indications where patients should be denied treatment with standard-of-care DES therapy. The two major causes of stent failure are stent thrombosis (ST) and in-stent restenosis (ISR). The incidence of both has reduced considerably in recent years. Current clinical registries and randomized trials with broad inclusion criteria show rates of ST at or <1% after 1 year and ∼0.2-0.4% per year thereafter; rates of clinical ISR are 5% respectively. Angiographic surveillance studies in large cohorts show rates of angiographic ISR of ∼10% with new-generation DES. The advent of high-resolution intracoronary imaging has shown that in many cases of late stent failure neoatherosclerotic change within the stented segment represents a final common pathway for both thrombotic and restenotic events. In future, a better understanding of the pathogenesis of this process may translate into improved late outcomes. Moreover, the predominance of non-stent-related disease as a cause of subsequent myocardial infarction during follow-up highlights the importance of lifestyle and pharmacological interventions targeted at modification of the underlying disease process. Finally, although recent developments focus on strategies which circumvent the need for chronically indwelling stents--such as drug-coated balloons or fully bioresorbable stents-more data are needed before the wider use of these therapies can be advocated.

Gradual increase in thrombogenicity of juvenile platelets formed upon offset of prasugrel medication

In patients with acute coronary syndrome, dual antiplatelet therapy with aspirin and a P2Y12 inhibitor like prasugrel is prescribed for one year. Here, we investigated how the hemostatic function of platelets recovers after discontinuation of prasugrel treatment. Therefore, 16 patients who suffered from ST-elevation myocardial infarction were investigated. Patients were treated with aspirin (100 mg/day, long-term) and stopped taking prasugrel (10 mg/day) after one year. Blood was collected at the last day of prasugrel intake and at 1, 2, 5, 12 and 30 days later. Platelet function in response to ADP was normalized between five and 30 days after treatment cessation and in vitro addition of the reversible P2Y12 receptor antagonist ticagrelor fully suppressed the regained activation response. Discontinuation of prasugrel resulted in the formation of an emerging subpopulation of ADP-responsive platelets, exhibiting high expression of active integrin αIIbβ3. Two different mRNA probes, thiazole orange and the novel 5'Cy5-oligo-dT probe revealed that this subpopulation consisted of juvenile platelets, which progressively contributed to platelet aggregation and thrombus formation under flow. During offset, juvenile platelets were overall more reactive than older platelets. Interestingly, the responsiveness of both juvenile and older platelets increased in time, pointing towards a residual inhibitory effect of prasugrel on the megakaryocyte level. In conclusion, the gradual increase in thrombogenicity after cessation of prasugrel treatment is due to the increased activity of juvenile platelets.

Dual antiplatelet therapy duration after the placement of a drug-eluting stent: what are the data?

OPINION STATEMENT

The data supporting the immediate use of dual antiplatelet therapy (DAPT) post implantation of drug-eluting stents (DESs) is irrefutable. DAPT in this early period is necessary to prevent stent thrombosis during endothelialization of the stent, a process known to be delayed when DESs are placed. In addition, DAPT helps prevent thrombosis from plaque rupture that occurs outside of the initial stented area and/or at neo-atherosclerotic lesions within a previously coated stent. The ACC/AHA current guidelines (Levine et al. J Am Coll Cardiol. 58(24):e44-122, 2011) recommend 12 months of DAPT post DES implantation. As the result of several randomized clinical trials (Task Force on Myocardial Revascularization of the European Society of Cardio-Thoracic Surgery (EACTS) et al. Eur Heart J. 31(20):2501-55, 2010) showing the safety of a shorter duration of DAPT, the European Heart Society altered their recommendations to 6-12 months of DAPT post DES implantation. However, recent data from the DAPT trial (Mauri et al. N Engl J Med. 371(23):2156-66, 2014) clearly demonstrated less ischemic events with 30 months of DAPT. This trial and others have established that an increased DAPT duration increases bleeding risk which, in turn, increases subsequent morbidity and mortality. The current conundrum lies in defining the optimal time of DAPT post DES to adequately reduce ischemic events while minimizing bleeding risks. Future studies are required to better stratify patients into low and high risk for both ischemic and bleeding risks to assess whether shorter or longer courses of DAPT are the most appropriate for any specific patients. Until then, instead of a "one size fits all" approach to patients who receive DESs, the treating physician must consider both procedural and patient factors when deciding the optimal duration of DAPT for each patient.

Optimal Duration of Dual Antiplatelet Therapy After Implantation of Drug-Eluting Stents: Shorter or Longer?

Use of dual antiplatelet therapy (DAPT; the combination of aspirin and an inhibitor of platelet P2Y₁₂) is the key pharmacological component in the management of acute coronary syndrome and percutaneous coronary intervention (PCI) with stent implantation, but the optimal treatment duration is still unclear. Although current guidelines recommend prescription of DAPT for at least 12 months after implantation of drug-eluting stents (DES) if patients are not at high risk of bleeding, several studies showed conflicting results. Observational studies have shown inconsistent findings (i.e., some studies suggested longer duration would be better, and others vice versa) and small-to-moderate sized randomized clinical trials suggested that prolonged use of DAPT beyond 12 months would not be more beneficial and could be detrimental in safety outcomes. However, these studies suffer from insufficient statistical power, data from old version of DES, and non-uniform duration of DAPT. Given there might be the relative risk and benefit associated with combination of DES use and DAPT prescription, the optimal decision making with regard to DAPT duration would be essential for patients who underwent PCI with DES. Thus, by understanding and comparing the evidences of recent studies that support for shorter and longer duration of DAPT, we sought to guide the treating physician in deciding optimal duration of DAPT in such patients. Up to now, there is no strong evidence supporting that longer duration of DAPT is better than shorter duration of DAPT in terms of efficacy and safety outcomes after DES placement.

Evidence of platelet sensitization to ADP following discontinuation of clopidogrel therapy in patients with stable coronary artery disease

Epidemiological studies have linked clopidogrel discontinuation with an increased incidence of ischemic events. This has led to the hypothesis that clopidogrel discontinuation may result in a pharmacological rebound. We evaluated the impact of clopidogrel discontinuation on platelet function. Platelet aggregation was measured by light transmission aggregometry (LTA) in response to adenosine diphosphate (ADP) 0.5, 1, 1.5, 2.5, 5 and 10 µM and by VerifyNow® P2Y12, in 37 clinically stable coronary artery disease (CAD) patients scheduled to discontinue clopidogrel treatment, and 37 clinically stable CAD patients not taking clopidogrel. Platelet function was assessed the day before clopidogrel cessation and 1, 3, 7, 14, 21 and 28 days after. Clopidogrel had been initiated a median of 555 days (ranging from 200 to 2280 days) before the treating cardiologist recommended its discontinuation. All participants were taking aspirin, most commonly 80 mg daily although a minority was prescribed 325 mg daily. Following clopidogrel discontinuation, VerifyNow® P2Y12 did not detect any rebound platelet activity, but ADP-induced LTA showed platelet sensitization to ADP, particularly at low ADP levels. Increased platelet activity was detectable seven days after clopidogrel cessation and remained higher than in controls 28 days after discontinuation. No clinical event occurred in any of the participants during the 28 days following clopidogrel cessation. In conclusion, platelet sensitization to ADP as a consequence of chronic clopidogrel administration may partially explain the recrudescence of ischemic events following clopidogrel discontinuation in otherwise stable coronary artery patients.