What is the recommended dual antiplatelet therapy (DAPT) regimen for 1 year, followed by single antiplatelet therapy, for a patient with single vessel disease who has undergone percutaneous coronary intervention (PCI)?

Antiplatelet Therapy for Single Vessel Disease After PCI

Standard Regimen: DAPT for 6-12 Months, Then Single Antiplatelet Indefinitely

For patients with single vessel disease undergoing elective PCI (stable ischemic heart disease), administer dual antiplatelet therapy with aspirin 75-100 mg daily plus clopidogrel 75 mg daily for a minimum of 6 months after drug-eluting stent implantation, then transition to single antiplatelet therapy (either aspirin 75-100 mg daily or clopidogrel 75 mg daily) indefinitely. 1

Initial DAPT Phase (First 6-12 Months)

• Aspirin: 75-100 mg (or 81 mg) daily starting immediately and continuing throughout DAPT 1
• P2Y12 inhibitor: Clopidogrel 75 mg daily is the standard choice for stable ischemic heart disease 1
• Minimum duration: 6 months for drug-eluting stents (DES), 1 month for bare-metal stents (BMS) 1

The 2016 ACC/AHA guidelines establish these as Class I (should be given) recommendations with strong evidence 1. The 6-month minimum for DES reflects improved safety profiles of newer-generation drug-eluting stents compared to earlier devices 2.

Transition to Single Antiplatelet Therapy (After 6-12 Months)

After completing the initial DAPT period, discontinue one antiplatelet agent and continue monotherapy indefinitely 1, 3:

• Option 1: Aspirin 75-100 mg daily (traditional approach) 1, 3
• Option 2: Clopidogrel 75 mg daily (equivalent alternative if aspirin intolerant) 1, 3

The 2012 CHEST guidelines explicitly recommend single antiplatelet therapy over continuation of dual therapy after the first year, citing this as Grade 1B evidence 1. This reduces bleeding risk while maintaining cardiovascular protection 1, 3.

Extended DAPT: When to Consider Continuation Beyond 6 Months

May extend DAPT beyond 6 months (up to 12 months or longer) if the patient:

• Has tolerated DAPT without bleeding complications AND
• Is not at high bleeding risk (no prior bleeding on DAPT, no coagulopathy, not on oral anticoagulation) 1

This is a Class IIb recommendation (may be reasonable), meaning it's optional based on individual assessment 1. The decision balances ischemic protection against bleeding risk.

Shortened DAPT: When to Stop at 3 Months

Consider discontinuing P2Y12 inhibitor after only 3 months if the patient develops:

• High bleeding risk (e.g., requires oral anticoagulation therapy) OR
• High risk of severe bleeding complication (e.g., major intracranial surgery planned) OR
• Significant overt bleeding 1

This early cessation is also Class IIb (may be reasonable) and should only be implemented when bleeding concerns clearly outweigh ischemic risks 1.

Critical Distinctions: Stable Disease vs. Acute Coronary Syndrome

This 6-month minimum applies specifically to stable ischemic heart disease (single vessel disease, elective PCI). If the patient had presented with acute coronary syndrome (unstable angina, NSTEMI, or STEMI), the recommendations differ substantially 1, 4:

• ACS patients require 12 months of DAPT minimum (not 6 months) 1, 4
• ACS patients should receive ticagrelor or prasugrel (not clopidogrel) as the P2Y12 inhibitor 1, 4, 5

The question specifies single vessel disease undergoing PCI, which typically represents stable disease rather than ACS, making the 6-month regimen appropriate 1.

Practical Implementation Algorithm

Month 0 (PCI procedure):

• Start aspirin 75-100 mg daily + clopidogrel 75 mg daily 1

Months 1-6:

• Continue both agents 1
• Monitor for bleeding complications 1

Month 6 assessment:

• If no bleeding issues and not high bleeding risk: Consider continuing DAPT up to 12 months 1
• If bleeding concerns or high bleeding risk: Stop clopidogrel, continue aspirin alone 1
• Standard approach: Stop clopidogrel, continue aspirin alone 1

After Month 12:

• Continue single antiplatelet therapy (aspirin or clopidogrel) indefinitely 1, 3

Common Pitfalls to Avoid

Never discontinue both antiplatelet agents simultaneously - always maintain at least one agent for secondary prevention 1, 3. Abrupt cessation of all antiplatelet therapy dramatically increases thrombotic risk 5.

Never extend DAPT indefinitely without reassessing bleeding risk - prolonged DAPT beyond 12 months increases major bleeding by 2-3 fold without proportional ischemic benefit in stable disease 1. The 2016 ACC/AHA guidelines specifically caution against routine extended DAPT in stable patients 1.

Never use prasugrel or ticagrelor for stable ischemic heart disease - these potent P2Y12 inhibitors are reserved for ACS patients 1, 4, 5, 6. Clopidogrel is the appropriate choice for elective PCI 1.

Never use high-dose aspirin (>100 mg) during DAPT - doses above 100 mg increase bleeding without improving efficacy 1, 4. The optimal dose is 75-100 mg daily 1.

Never forget proton pump inhibitor co-prescription - PPIs significantly reduce gastrointestinal bleeding risk in patients on antiplatelet therapy and should be prescribed routinely, especially in those with prior GI bleeding, elderly patients, or those on multiple antithrombotic agents 4, 5, 3.

Emerging Evidence: P2Y12 Inhibitor Monotherapy

Recent trials have explored discontinuing aspirin (rather than clopidogrel) after short DAPT, continuing P2Y12 inhibitor monotherapy instead 7, 8, 9. This aspirin-free strategy shows reduced bleeding without increased ischemic events in some studies 7, 8, 9. However, this approach is not yet incorporated into major guidelines 1, 4 and remains investigational for routine practice. The standard remains aspirin monotherapy after DAPT cessation 1, 3.