Definition and pathophysiology
Dual antiplatelet therapy (DAPT) is the combined use of aspirin and an oral P2Y12 receptor inhibitor. It is central to the prevention of platelet-mediated coronary thrombosis after acute coronary syndrome (ACS) and percutaneous coronary intervention (PCI).
Aspirin irreversibly inhibits cyclooxygenase and thereby suppresses thromboxane A2 synthesis, reducing platelet activation and aggregation. Its antiplatelet effect begins within approximately 30–60 minutes and persists for up to 7 days after discontinuation because platelet inhibition is irreversible. Aspirin acts through only one platelet-activation pathway; P2Y12 inhibition therefore provides complementary platelet inhibition.
The clinical rationale for DAPT is particularly strong after ACS and coronary stent implantation. ACS is associated with a high risk of platelet-driven atherothrombosis, while interruption of antiplatelet therapy after recent stenting is associated with increased risk of major adverse cardiovascular events (MACE) and stent thrombosis. Premature DAPT interruption is described as the strongest predictor of stent thrombosis in this setting.
The duration of therapy requires an individualized balance between:
- Ischaemic risk, including recurrent myocardial infarction and stent thrombosis.
- Bleeding risk, particularly major or life-threatening bleeding.
- The clinical presentation, whether ACS or chronic coronary syndrome (CCS).
- Whether and how PCI was performed.
- The need for non-cardiac surgery.
- The presence of an indication for oral anticoagulation (OAC).
Clinical context and treatment objectives
DAPT is used in two principal settings:
- After ACS, whether managed medically or with revascularization.
- After elective PCI for CCS, particularly after stent implantation.
In both situations, DAPT is generally a temporary strategy. At an appropriate point, it is usually replaced by single antiplatelet therapy (SAPT), most often aspirin. In selected patients, P2Y12 inhibitor monotherapy may be used as a de-escalation strategy after a period of DAPT.
The therapeutic objective is to reduce coronary thrombotic events without exposing the patient to disproportionate bleeding risk. Shortening treatment may reduce bleeding but can increase myocardial infarction or stent thrombosis in some ACS populations; prolonging treatment may reduce ischaemic events but increases bleeding.
Standard DAPT duration after ACS
Default strategy
The standard treatment after ACS is DAPT for 12 months, irrespective of stent type. The preferred regimen is aspirin plus a potent P2Y12 inhibitor, usually prasugrel or ticagrelor. In patients undergoing PCI for ACS, prasugrel should be considered in preference to ticagrelor, although the comparative evidence between prasugrel and ticagrelor is conflicting.
A 12-month regimen remains the default for most patients with ACS, including those with NSTE-ACS. It applies whether ACS is managed with PCI or without revascularization, although the exact antithrombotic strategy may differ when long-term OAC is also indicated.
Possible shortening of DAPT
A duration of 6 months after ACS is generally considered too short for routine use, but it may be considered in selected patients with a high bleeding risk. Shorter approaches should therefore be reserved for circumstances in which bleeding concerns outweigh the incremental protection from prolonged DAPT.
Trials evaluating abbreviated DAPT have generally shown a reduction in bleeding, but some have also demonstrated increased ischaemic complications. In a large network meta-analysis, 3-month DAPT, but not 6-month DAPT, was associated with higher rates of myocardial infarction or stent thrombosis in ACS patients.
Extension beyond 12 months
DAPT beyond 12 months may be considered in patients who:
- Have tolerated DAPT without significant bleeding.
- Have high ischaemic risk.
- Do not have a high risk of major or life-threatening bleeding.
Extended treatment may also be considered in patients with moderate ischaemic risk when bleeding risk is not high, although the expected benefit is lower. The benefit–risk balance should be reassessed rather than assuming that DAPT should continue indefinitely.
The evidence base for prolonged treatment involved treatment periods of approximately 18 months in one major DAPT study, a mean of 23 months in a dual-pathway inhibition study, and a median of 33 months in a long-term ticagrelor study. The balance of benefit and harm beyond these durations remains uncertain.
DAPT duration after elective PCI for chronic coronary syndromes
Standard strategy
After elective PCI for CCS, the standard DAPT duration is 6 months. Clopidogrel is the usual P2Y12 inhibitor. Prasugrel or ticagrelor may be considered after complex interventions.
After the standard period, DAPT is generally replaced by SAPT. Aspirin is the usual maintenance drug in patients without allergy or another contraindication.
Shortening DAPT
In patients with very high bleeding risk, DAPT after elective PCI may be shortened to 1–3 months. The decision should reflect the individual’s procedural and clinical ischaemic risk, the bleeding risk, and the characteristics of the stent and intervention.
Recent evidence indicates that, in selected low- and moderate-risk patients with modern drug-eluting stents, DAPT durations of 1–3 months may be associated with acceptable rates of MACE and stent thrombosis. These data do not eliminate the need for individualized assessment, particularly in patients with high-risk coronary anatomy or ACS.
Prolongation after elective PCI
DAPT beyond 12 months is an option for patients with high ischaemic risk who tolerate therapy well and do not have a high bleeding risk. In stable CAD, another long-term option is dual-pathway inhibition with rivaroxaban 2.5 mg twice daily plus aspirin, although this improves cardiovascular outcomes at the cost of more major bleeding than aspirin alone.
Antiplatelet agents
Aspirin
Aspirin is the standard background antiplatelet agent for DAPT and the most commonly used drug for long-term SAPT.
For PCI:
- Patients already receiving chronic aspirin should receive 81–325 mg before PCI.
- Patients not taking long-term aspirin should receive 325 mg at least 2 hours, and preferably 24 hours, before PCI.
- After PCI, aspirin is generally continued indefinitely if there is no allergy or contraindication.
- A lower maintenance dose, such as 81 mg daily, may be preferable to reduce gastrointestinal bleeding risk.
In selected patients, aspirin may be discontinued after a short period of DAPT, with continuation of P2Y12 inhibitor monotherapy for 1–3 months after PCI.
Clopidogrel
Clopidogrel is the preferred P2Y12 inhibitor after elective PCI for CCS. It is also used when aspirin is contraindicated or when combined antithrombotic treatment is required in patients with AF.
For patients with true aspirin allergy, the stated alternative is:
- Clopidogrel 75 mg once daily.
After STEMI, clopidogrel 75 mg daily is used in patients managed with medical therapy alone, fibrinolytic therapy, or PCI when clinically appropriate.
Prasugrel
Prasugrel is a preferred potent P2Y12 inhibitor after ACS treated with PCI and should be considered in preference to ticagrelor in this setting. The dose stated for post-STEMI treatment is:
- Prasugrel 10 mg once daily in patients treated with PCI.
The supplied material does not provide additional dosing restrictions or contraindications.
Ticagrelor
Ticagrelor is a preferred P2Y12 inhibitor after ACS. The dose stated after STEMI is:
- Ticagrelor 90 mg twice daily in patients treated with medical therapy alone or PCI.
Ticagrelor may also be used as part of prolonged antithrombotic treatment in selected patients with high ischaemic risk and low bleeding risk. After carotid stenting, however, ticagrelor included in DAPT has been associated with a higher bleeding risk than clopidogrel.
P2Y12 inhibitor monotherapy
P2Y12 inhibitor monotherapy may be used after a period of DAPT as part of a de-escalation strategy after PCI or ACS. It may also be relevant in patients with recent stroke, peripheral arterial disease, or aspirin intolerance.
The choice between continuing aspirin and switching to P2Y12 inhibitor monotherapy requires assessment of ischaemic and bleeding risks. The source material does not establish a single preferred monotherapy strategy for all patients.
Selection of DAPT duration
The decision can be structured around the following factors.
| Clinical situation | Default or usual DAPT strategy |
|---|---|
| ACS, with or without PCI | 12 months |
| ACS with high bleeding risk | Shortening may be considered; 6 months may be appropriate in selected patients |
| ACS with high ischaemic risk and low bleeding risk | Consider extension beyond 12 months |
| Elective PCI for CCS | 6 months |
| Elective PCI with very high bleeding risk | Consider 1–3 months |
| Elective PCI with high ischaemic risk and low bleeding risk | Prolonged DAPT may be considered |
| Stable CAD with suitable risk profile | Aspirin plus rivaroxaban 2.5 mg twice daily may be considered as dual-pathway inhibition |
The choice should not be based solely on the nominal indication. It should incorporate bleeding history and risk, the complexity of PCI, the presence of ACS, tolerance of initial therapy, and the need for surgery or OAC.
Peri-operative management
Timing of non-cardiac surgery
Elective non-cardiac surgery should generally be delayed until the recommended DAPT course is complete:
- 6 months after elective PCI.
- 12 months after ACS.
When surgery is time-sensitive after elective PCI, at least 1 month of DAPT should ideally be completed first. In high-risk cardiovascular patients, such as those with STEMI or high-risk NSTE-ACS, at least 3 months of DAPT should be considered before time-sensitive surgery.
The decision should be made through discussion among the surgeon, anaesthesiologist, and cardiologist.
Continuing aspirin
In patients with previous PCI, aspirin should generally be continued peri-operatively if the bleeding risk permits. Once the P2Y12 inhibitor has been stopped, surgery should ordinarily proceed while aspirin is maintained.
For operations with very high bleeding consequences, including intracranial, spinal neurosurgical, or vitreoretinal procedures, aspirin interruption for at least 7 days is recommended.
In patients without previous PCI, stopping aspirin at least 3 days before surgery may be considered when bleeding risk outweighs ischaemic risk.
Interruption intervals for P2Y12 inhibitors
When interruption is necessary before non-cardiac surgery, the recommended intervals are:
| P2Y12 inhibitor | Recommended pre-operative interruption |
|---|---|
| Ticagrelor | 3–5 days |
| Clopidogrel | 5 days |
| Prasugrel | 7 days |
After surgery, interrupted antiplatelet therapy should be restarted as soon as possible, preferably within 48 hours, provided that the interdisciplinary assessment supports resumption.
Surgery during P2Y12 inhibitor monotherapy
Patients receiving P2Y12 inhibitor monotherapy after PCI or ACS may require individualized peri-operative planning. Possible approaches include operating while continuing P2Y12 monotherapy, switching to aspirin, briefly interrupting treatment, or bridging. Evidence is insufficient to define one universally applicable strategy, and the decision should be based on the relative peri-operative bleeding and ischaemic risks.
Platelet function testing
Platelet function testing has been considered for estimating peri-operative bleeding risk, selecting the timing of surgery after antiplatelet cessation, and guiding treatment during bleeding complications. However, neither a universally appropriate assay nor a validated threshold associated with surgical bleeding has been established.
Patients requiring oral anticoagulation
Atrial fibrillation is the most common reason for long-term OAC in patients with ACS or PCI. Combining OAC with antiplatelet therapy increases bleeding risk and requires a separate strategy from conventional DAPT.
For most patients with AF undergoing PCI or presenting with ACS:
- Peri-procedural triple therapy with OAC, aspirin, and a P2Y12 inhibitor is the default.
- Triple therapy should generally be limited to ≤1 week.
- This is followed by dual therapy with a direct oral anticoagulant, at the stroke-prevention dose, plus a single oral antiplatelet agent, preferably clopidogrel.
The combination of OAC and a P2Y12 inhibitor produces less major bleeding than triple therapy that includes aspirin. Evidence for combining ticagrelor or prasugrel with OAC is less clear, and bleeding risk is higher; clopidogrel is therefore preferred.
Triple therapy may be extended to 1 month in patients with high ischaemic risk, such as those with STEMI, previous stent thrombosis, complex coronary procedures, or prolonged cardiac instability. In patients with ACS or PCI and diabetes, extension to 3 months may be beneficial when thrombotic risk clearly exceeds bleeding risk.
For ACS managed without revascularization, 6–12 months of a single antiplatelet agent, usually clopidogrel, together with long-term DOAC therapy is generally sufficient. In stable CCS more than 12 months after the coronary event or intervention, DOAC monotherapy is considered sufficient and additional antiplatelet therapy is not required.
When a vitamin K antagonist is combined with antiplatelet therapy, an INR range of 2.0–2.5 is recommended by consensus to mitigate excess bleeding. Proton pump inhibitor therapy is reasonable when gastrointestinal bleeding risk is a concern during combined antithrombotic treatment.
Management of ACS beyond DAPT duration
Antithrombotic therapy is indicated in all ACS patients and includes both antiplatelet and anticoagulant treatment during the acute phase.
The acute strategy includes:
- Aspirin loading and maintenance therapy.
- Addition of a P2Y12 inhibitor, generally continued for 12 months unless bleeding risk is excessive.
- Preference for prasugrel or ticagrelor over clopidogrel in ACS when appropriate.
- Consideration of prasugrel over ticagrelor in ACS patients undergoing PCI.
- Parenteral anticoagulation at diagnosis, with discontinuation considered immediately after the invasive procedure.
- Avoidance of routine P2Y12 pretreatment before coronary angiography in NSTE-ACS, although pretreatment may be considered in STEMI patients undergoing primary PCI.
The subsequent maintenance plan should be reassessed as ischaemic and bleeding risks evolve over time.
Guideline recommendations
The recommendations summarized in the source material are as follows:
| Recommendation | Class | Level |
|---|---|---|
| Delay elective non-cardiac surgery until 6 months after elective PCI and 12 months after ACS | I | A |
| After elective PCI, delay time-sensitive surgery until at least 1 month of DAPT has been completed | I | B |
| Discuss peri-operative antiplatelet management among surgeon, anaesthesiologist, and cardiologist | I | C |
| Consider at least 3 months of DAPT before time-sensitive surgery in high-risk patients with recent PCI | IIa | C |
| Continue aspirin peri-operatively after previous PCI when bleeding risk permits | I | B |
| Withhold ticagrelor for 3–5 days, clopidogrel for 5 days, and prasugrel for 7 days before surgery when interruption is required | I | B |
| Interrupt aspirin for at least 7 days before very high bleeding-risk surgery | I | C |
| In patients without prior PCI, consider aspirin interruption for at least 3 days when bleeding risk outweighs ischaemic risk | IIb | B |
| Restart interrupted antiplatelet therapy as soon as possible, within 48 hours when feasible | I | C |
For ACS, the default is 12 months of DAPT with aspirin and a potent P2Y12 inhibitor. For elective CCS-PCI, the standard is 6 months, with shortening to 1–3 months in patients with very high bleeding risk. Prolonged DAPT is an option for patients with high ischaemic risk who have tolerated therapy and do not have increased risk of major or life-threatening bleeding.
Prognosis and follow-up
The prognosis after ACS or PCI depends substantially on maintaining an appropriate balance between prevention of recurrent thrombosis and avoidance of bleeding. Both ischaemic and bleeding events decline markedly over time after PCI for ACS, so the net benefit of continued DAPT should be reconsidered as the patient moves from the acute phase into long-term secondary prevention.
Particular caution is required around non-cardiac surgery. Major adverse cardiovascular events after PCI in patients undergoing surgery have been reported in the range of 2–8%, with risk more than twice that observed in patients without coronary stents. The highest risk occurs during the first month after PCI. Other adverse factors include primary PCI for STEMI, interruption or discontinuation of DAPT, ostial or distal lesions, and urgent surgery.
Follow-up should therefore include:
- Reassessment of recurrent ischaemic risk.
- Review of bleeding events and modifiable bleeding risks.
- Confirmation that the planned DAPT duration remains appropriate.
- Evaluation of adherence and tolerance.
- Reassessment before any invasive procedure or surgery.
- Transition to SAPT or another long-term antithrombotic strategy when indicated.
For patients with persistent high ischaemic risk and low bleeding risk, extended intensified antithrombotic therapy may be appropriate. For patients whose bleeding risk increases, de-escalation, P2Y12 inhibitor monotherapy, or transition to SAPT should be considered. The precise duration of treatment beyond the periods studied in clinical trials remains uncertain, reinforcing the need for periodic individualized review.