Antiplatelet Therapy Following Stent Implantation
Condition: Acute Myocardial Infarction; Coronary Syndrome; Angina, Unstable
MeSH terms: Myocardial Infarction; Angina, Unstable; Infarction
Study type: Observational

Summary: 
      Coronary artery stents, particularly drug-eluting stents (DES), are used in the majority of
      patients who undergo percutaneous coronary intervention (PCI) to improve symptoms in patients
      with obstructive coronary artery disease. They function both to prevent abrupt closure of the
      stented artery soon after the procedure as well as to lower the need for repeat
      revascularization compared to balloon angioplasty alone . Stent restenosis and stent
      thrombosis are potential complications of coronary artery stenting; their incidence is
      highest in the first year after PCI. Stent restenosis, which occurs more frequently with bare
      metal stents (BMS) than DES, may occasionally present as an acute myocardial infarction (MI).
      Stent thrombosis is an uncommon but serious complication that often presents as death and is
      almost always accompanied by MI, usually with ST-segment elevation. Patients are commonly
      treated with dual antiplatelet therapy (DAPT) for the recommended duration for the particular
      stent. DAPT (aspirin plus platelet P2Y12 receptor blocker) and significantly lowers the risk
      of stent thrombosis.
    

Detailed description: 
      New Guidance on Antiplatelet Therapy After Stenting: Clinical Advisory, Kirsten E.
      Fleischmann, MD, MPH reviewing Grines CL et al. Circulation 2007 Feb 13. An expert panel
      recommends 12 months of therapy after placement of drug-eluting stents. Aspirin and
      clopidogrel are commonly prescribed after placement of both bare metal stents and
      drug-eluting stents. However, recent concerns about stent thrombosis (Journal Watch Jan 4
      2007) have led experts from multiple groups, including the American Heart Association and the
      American College of Cardiology, to issue an advisory on preventing premature discontinuation
      of dual antiplatelet therapy. Based on a review of the literature, the experts offer
      observations and recommendations including the following:

        -  Dual antiplatelet therapy with aspirin and a thienopyridine such as clopidogrel reduces
           cardiac events after coronary stenting.

        -  Premature discontinuation of these agents greatly increases the risk for stent
           thrombosis and associated clinical events such as myocardial infarction and death.

        -  Patients should receive 12 months of dual antiplatelet therapy after placement of
           drug-eluting stents.

        -  Elective surgery associated with a significant risk for bleeding should be postponed
           until an appropriate course of dual antiplatelet therapy (i.e., 1 month for bare metal
           stents and 12 months for drug-eluting stents) has been completed.

        -  Patients' ability to comply with prolonged dual antiplatelet therapy and their need for
           subsequent invasive procedures should be considered when choosing the type of stent.

        -  Patients and their other providers should consult with the patient's cardiologist before
           stopping dual therapy.

      Endpoints:

      Primary endpoint - Outcome Measures:

      1. Major Cardiovascular events at 1, 3, 6, 12 months after study enrolment

        -  All Death,

        -  Cardiac death,

        -  Myocardial infarction,

        -  Stroke,

        -  Target vessel revascularization

        -  Bleeding event

        -  In-stent restenosis (ISR)

             -  Angiographical Determination of Binary Stenosis Rate (defined as diameter stenosis
                of at least 50 % in the stent and / or persistent area, 6, 9, 12 months after stent
                implantation) The angiographical determination of the degree of stenosis, defined
                as percentage diameter stenosis in the stent and /or persistent area, 6 and 12
                months after stent implantation.

             -  The angiographical determination of the minimal lumen diameter in the stent and /
                or persistent area, 6 months after stent implantation.

      Secondary:

        -  Description of any reported AE/ SAE per study subgroup.

        -  Description of any missing doses per study subgroup.

      Study Medication:

      Category: ADP-P2Y12 interaction blokers

        -  Clopidogrel (Clovelen®)

        -  Dosage: As per Clopidogrel (Clovelen®) SmPC

      Study Concomitant Medication:

      Aspirin. DAT = Dual antiplatelet therapy consists of aspirin add on clopidogrel
    

Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Patients on clopidogrel treatment following stent implantation
      
Keywords: DAT = Dual Antiplatelet Treatment; Major Cardiac Adverse Events