dual antiplatelet therapy (DAPT)

Pharmacology

• therapy with two antiplatelet agents generally clopidogrel & aspirin
• low-dose aspirin (75-100 mg/day) in all regimens
• it seems persantine & aspirin would also qualify, though these two agents are less commonly associated with the term DPAT
• ticagrelor may be preferred to clopidogrel after acute coronary syndrome without stent Adverse events:
• risk of hemorrhage* (resulting in emergency department visit) associated with dual antiplatelet therapy is less than that for warfarin (3.7 vs 1.2 per 1000 outpatient prescription visits)
• nuisance bleeding is common during the first year after MI, & adversely affects quality of life
• DAPT for > 12 months associated with higher rate of bleeding- related mortality (RR=0.1.5), but lower rate of myocardial infarction (RR=0.75) than DAPT for < 12 months
  • all-cause mortality also higher with > 12 months DAPT (RR=1.2)
• long-term DAPT (> 12 months) associated with decreased risks for myocardial infarction & stent thrombosis but increased risks for noncardiac death &major bleeding relative to short-term DAPT (< 6 months)
• 1-3 months of dual anti-platelet therapy sufficient after PCI with drug-eluting coronary stent
• dual antiplatelet therapy increases risk of systemic bleeding after ischemic stroke ~5-6 events per 100 patient-years relative to monotherapy, but may not increase risk of intracerebral hemorrhage
• dual antiplatelet therapy for ischemic stroke or TIA in patients with low LDL-cholesterol further increases risk of systemic bleeding

* proton pump inhibitor provides protection from GI bleeding without affecting adverse cardiovascular risk

Indications

• following coronary stent (one year of therapy)
  • 6-12 months for drug-eluting stent
    • 3 months may be reasonable in patients with high risk of bleeding
  • > 1 month for bare metal stent
• following acute coronary syndrome or MI (STEMI, NSTEMI)
  • >= 12 months of therapy
• patients with stable CAD undergoing CABG
  • 12 months of therapy

Contraindications

• secondary prevention of cardiovascular events
• patients with diabetes mellitus & coronary artery disease
• chronic stable angina in the absence of revascularization

Benefit/risk

• for 1 year following coronary stent
  • no mortality benefit
  • number needed to treat (NNT) to prevent 1 non-fatal MI or 1 stroke = 27
  • number need to harm (major hemorrhage) = 117
• no benefit for secondary prevention of cardiovascular events
• reduces risk of new stroke after TIA or ischemic stroke at cost of increased risk of bleeding vs aspirin alone
  • 1-3 weeks of DAPT after TIA or ischemic stroke
    • benefits of DAPT are front-loaded, bleeding risks are constant

Management

• duration of therapy is usually 6-12 months
• 12 months of dual antiplatelet therapy after PCI with drug- eluting stent is the standard of care
  • 3-6 months of dual antiplatelet therapy is associated with less bleeding but no difference in ischemia or thrombosis relative to 12 months of therapy
  • > 6 months of dual antiplatelet therapy is associated with fewer MIs but more bleeding & more deaths relative to < 6 months of therapy, but absolute risk is low (0.03% for MI)*
  • 12 months of therapy does not decrease risk of myocardial infarction, cardiac death or stent thrombosis & increases risk of bleeding relative to 6 months of therapy with or without type 2 diabetes
  • 6 months of DAPT after drug-eluting stent for STEMI non-inferior to 12 months of DAPT
• mortality benefit for prolonged dual antiplatelet therapy is unlikely
• Dual Antiplatelet therapy score (DAPT score) may predict patients that might benefit from prolonged dual antiplatelet therapy
• elective non-cardiac surgery should be delayed at least 30 days after bare metal stent implantion & 6 months after drug-eluting stent implantation (i.e. after DAPT is complete)

* calculator to predict risks of ischemic events vs bleeding for continued DAPT therapy beyond 1 year after coronary stent placement

More general terms

• pharmacologic therapy

Additional terms

• antiplatelet agent
• Dual AntiPlatelet Therapy score (DAPT score)