#72 Dual Antiplatelet Therapy Following Drug-Eluting Stent Placement: 3 Months, 1 Year or Forever?

CLINICAL QUESTION

In patients with coronary artery disease who have drug-eluting stent (DES) placement, how long should we prescribe dual antiplatelet therapy (DAPT), such as aspirin plus clopidogrel?

BOTTOM LINE

Current evidence shows small reductions in cardiovascular events balanced by a small increase in major bleed and mortality for DAPT duration >12 months. Guidelines recommend >12 months for ACS and >6 months for elective DES placement, with ½ these durations if major bleed occurs. Patient preferences and values should guide DAPT duration.

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EVIDENCE

Multiple meta-analyses of 11 Randomized Controlled Trials (RCTs), 33,051 patients comparing DAPT durations of 3-48 months following DES placement.

One meta-analysis¹ (10 RCTs) comparing “longer” versus “shorter” DAPT, statistically significant:
- Decreased risk of:
  - Myocardial infarction (MI): -0.8%/year, Number Needed to Treat (NNT)=125.
- Increased risk of:
  - All-cause mortality: +0.2%/year, Number Needed to Harm (NNH)=500.
  - Major bleed: +0.6%/year, NNH=167.
- Other meta-analyses^2-4 found:
  - 3-6 versus 12 months:
    - Death,2,3 MI/stent thrombosis:^2-4 No difference.
    - Major bleed: No difference² or reduction,^3,4 NNT=250-385.
  - 18-48 versus 6-12 months:
    - Death: No difference^2,3 or higher risk.⁴
    - MI/stent thrombosis: Reduction.^2-4
    - Major bleed: Increase.^2-4

Context:

2016 American DAPT guidelines5 recommend:
- Acute coronary syndrome (ACS) +/- stent placement: DAPT >12 months.
  - Consider stopping at six months if high bleed risk or develop overt bleed.
- DES placement for stable coronary artery disease: DAPT >6 months.
  - At six months, re-assess & consider for longer if low bleed risk.
  - Stop after three months if develop bleed.
Reduction of “very late” stent thrombosis (one year after DES placement), the primary goal of prolonged DAPT, rarely occurs with newer DES:
- 0.8% with 2nd generation DES versus 3% with paclitaxel-eluting stent (1st generation stent no longer used in practice).⁶
- In-hospital mortality is <4%⁷ (previously overestimated as 20-45%⁸).
Preliminary clinical predictions rules9,10 (such as the DAPT Score) describe factors to consider shorter/longer duration:
- Longer (increase MI): ACS/MI at presentation, prior MI/revascularization, heart failure or ejection fraction <30%, diabetes and certain stent/procedural factors.
- Shorter (increased bleed): Age, low/high BMI, anemia, and anticoagulation.

updated july 20 2016 by ricky