Antiplatelet Therapy Following Stent Implantation

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.

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

Eligibility Criteria:
Inclusion Criteria:

* Patients in whom planned or unplanned stent implantation
* Ages Eligible for Study: 18 Years and older
* Genders Eligible for Study: Both
* Acute coronary syndrome
* ST-segment elevation MI (STEMI)
* non ST-segment elevation MI (STEMI)
* Stable angina pectoris and or/ documented myocardial ischemia
* Instable angina pectoris and or/ documented myocardial ischemia
* De-novo stenosis of coronary artery with a degree of stenosis between 50% and 99%, that is accessible to PTCA
* Patients on pre-defined group of clopidogrel treatment during and after DES implantation
* Willingness and ability to adhere to the study conditions
* Written informed consent after patient information

Exclusion Criteria:

* Known severe arrhythmias that necessitate a long term antiarrhythmic therapy
* Pericarditis
* Intracardiac thrombus
* Bacterial endocarditis
* Patients with contraindication for aortocoronary bypass operation,
* Contraindication to antiplatelet therapy
* Non-cardiac co-morbid conditions that may result in protocol non-compliance (per site investigator's medical judgment).
* Bleeding diathesis
* Thrombocytopenia (\<150 000/mm3)
* Recent (\<6 months) gastrointestinal bleeding
* Recent stroke within 6-months
* Concurrent organ damage (creatinine level \> 2.0mg/dL or AST and ALT \> 3 times upper normal reference values)
* Patients with left main stem stenosis (\>50% by visual estimate)
* History of allergy to aspirin
* Inability, to understand sense and purpose of the study
* Patients not willing to keep the conditions of the study