At what degree of coronary artery stenosis is dual anti-platelet therapy with aspirin and Plavix typically initiated?

Dual Antiplatelet Therapy in Coronary Artery Disease

Dual antiplatelet therapy (DAPT) with aspirin and a P2Y12 inhibitor is recommended for patients with coronary artery stenosis only after stent placement or acute coronary syndrome, not based on the degree of stenosis alone. 1

Indications for DAPT

DAPT is indicated in the following scenarios:

• After stent placement:

  • Bare-metal stents: Minimum 1 month 1
  • Drug-eluting stents: 3-6 months (minimum), with suggestion to continue for 12 months 1

• After Acute Coronary Syndrome (ACS):

  • 12 months of DAPT regardless of management strategy (medical therapy or PCI) 1

• Stable Coronary Artery Disease (CAD):

  • Single antiplatelet therapy (aspirin 75-100 mg daily or clopidogrel 75 mg daily) is recommended for established CAD 1
  • DAPT is not recommended based solely on the degree of stenosis in stable CAD 1

P2Y12 Inhibitor Selection

For patients requiring DAPT:

• ACS patients:

  • Ticagrelor (180 mg loading, 90 mg twice daily) is recommended regardless of initial treatment strategy 1
  • Prasugrel (60 mg loading, 10 mg daily) is recommended for P2Y12-naïve patients with NSTE-ACS or STEMI undergoing PCI 1
  • Clopidogrel (600 mg loading, 75 mg daily) is recommended for patients who cannot receive ticagrelor or prasugrel 1

• Stable CAD patients undergoing PCI:

  • Clopidogrel (600 mg loading, 75 mg daily) is recommended 1

Duration of DAPT

The standard duration varies based on clinical scenario:

• Standard duration: 12 months for ACS patients 1, 2
• Shortened duration (3-6 months): For patients with high bleeding risk (PRECISE-DAPT ≥25) 1, 2
• Extended duration (>12 months): May be considered for patients with high thrombotic risk and low bleeding risk 2

Special Considerations

• Bleeding risk reduction:

  • Use radial over femoral access for coronary procedures 1
  • Use low-dose aspirin (75-100 mg daily) 1
  • Consider proton pump inhibitor in combination with DAPT 1

• Switching between P2Y12 inhibitors:

  • For ACS patients previously on clopidogrel, switching to ticagrelor is recommended early after hospital admission 1

• Patients requiring oral anticoagulation:

  • Triple therapy duration should be minimized 1
  • Consider dual therapy with clopidogrel and an oral anticoagulant as an alternative to triple therapy 1

Important Caveats

• Routine platelet function testing to adjust antiplatelet therapy is not recommended 1
• Prasugrel should be avoided in patients with prior stroke/TIA, age >75 years, or weight <60 kg 1
• Recent evidence suggests that clopidogrel monotherapy may be superior to aspirin monotherapy after completion of DAPT, with reductions in MACE and stroke 3

Remember that DAPT decisions should be based on clinical presentation, risk factors, and management strategy rather than solely on the degree of coronary stenosis. The balance between ischemic protection and bleeding risk must always be considered when determining DAPT duration.