Dual antiplatelet therapy after percutaneous coronary intervention is no longer a fixed prescription. Duration is a judgement about which of two risks is greater in the patient in front of you, and the evidence has moved decisively towards shorter courses in patients whose bleeding risk is high.
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The default durations
After PCI for an acute coronary syndrome, twelve months of DAPT remains the reference position. After PCI for chronic coronary syndrome, six months is the reference. Both are starting points to be adjusted, not endpoints. Potency also differs by indication: ticagrelor or prasugrel are preferred over clopidogrel after acute coronary syndrome, whereas clopidogrel remains standard in stable disease.
The trials that shortened them
TWILIGHT randomised patients who had completed three months of ticagrelor plus aspirin without event to continuing or dropping the aspirin. Ticagrelor monotherapy halved clinically relevant bleeding with no increase in death, infarction or stroke. TICO and STOPDAPT-2 pointed the same way with shorter lead-ins. MASTER DAPT tested one month of DAPT followed by single antiplatelet therapy specifically in patients at high bleeding risk and found no excess of ischaemic events with substantially less bleeding.
The direction of travel is consistent: a short period of genuine dual therapy to cover the vulnerable early window, then de-escalation to a single potent agent. Dropping the aspirin rather than the P2Y12 inhibitor is what most of this evidence supports.
Identifying high bleeding risk
The ARC-HBR framework is more useful at the bedside than a numerical score. Major criteria include anticipated long-term oral anticoagulation, severe or end-stage chronic kidney disease, haemoglobin below 11 g/dL, spontaneous bleeding requiring admission or transfusion in the previous six months, moderate or severe thrombocytopenia, chronic bleeding diathesis, cirrhosis with portal hypertension, active malignancy within twelve months, previous intracranial haemorrhage or ischaemic stroke, and planned major surgery on DAPT. One major or two minor criteria define high bleeding risk. HAS-BLED can be calculated here, but remember what it is for: identifying modifiable risk and prompting closer review, never a reason to leave a patient unprotected.
When to extend beyond twelve months
Extension is for patients whose ischaemic risk is high and whose bleeding risk is not: previous stent thrombosis, multivessel disease in a diabetic patient, a long or complex intervention, left main or last remaining vessel stenting, or recurrent infarction. Where DAPT is extended, a reduced-dose P2Y12 inhibitor is a reasonable strategy. The decision should be revisited at every annual review rather than left running by default, because bleeding risk rises with age while the marginal ischaemic benefit does not.
The patient who also needs anticoagulation
This is where most of the difficulty sits. AUGUSTUS, PIONEER AF-PCI and RE-DUAL PCI converge on the same answer: triple therapy should be measured in days rather than months. Give aspirin peri-procedurally and for up to a week, then continue a direct oral anticoagulant with clopidogrel alone to twelve months, and thereafter the anticoagulant by itself. Extending triple therapy buys very little ischaemic protection at a substantial bleeding cost. Use the licensed stroke-prevention dose of the anticoagulant, not a reduced one, unless the patient meets the specific reduction criteria for that agent.
A practical sequence
- Establish the indication — acute coronary syndrome or chronic coronary syndrome.
- Assess bleeding risk against ARC-HBR before leaving the laboratory, not at discharge.
- Note the procedural complexity that would argue for longer cover.
- Ask whether the patient needs anticoagulation for another reason.
- Set a duration, write it in the discharge summary as a date rather than an interval, and say who reviews it.
- Address the modifiable bleeding risks — proton pump inhibitor cover, blood pressure control, review of concomitant NSAIDs and alcohol.
Step five is the one most often omitted, and it is why patients arrive at a clinic four years later still taking two antiplatelet agents that nobody has revisited.
Related reading: acute stent thrombosis, the interventional and acute care reading list, and the Monday interventional case review.