What score should be used to decide whether to start Single AntiPlatelet Therapy (SAPT) or Dual AntiPlatelet Therapy (DAPT) in patients with coronary artery disease?

Risk Stratification for SAPT vs DAPT Decision-Making

Use the DAPT Score to guide the decision between continuing DAPT beyond the initial mandatory period versus transitioning to SAPT in patients with coronary artery disease who have completed their initial DAPT course without bleeding or ischemic complications. 1

The DAPT Score Algorithm

The DAPT Score is a validated risk prediction tool derived from the Dual Antiplatelet Therapy study that helps determine whether prolonged DAPT provides net benefit over transitioning to SAPT. 1

Score Calculation

Calculate points based on the following patient characteristics 1:

Positive predictors (favor prolonged DAPT):

• Current cigarette smoker: +1 point 1
• Diabetes mellitus: +1 point 1
• MI at presentation: +1 point 1
• Prior PCI or prior MI: +1 point 1
• Stent diameter <3 mm: +1 point 1
• Paclitaxel-eluting stent: +1 point 1
• Congestive heart failure or LVEF <30%: +2 points 1
• Saphenous vein graft PCI: +2 points 1

Negative predictors (favor SAPT):

• Age ≥75 years: -2 points 1
• Age 65 to <75 years: -1 point 1
• Age <65 years: 0 points 1

Score Interpretation and Decision-Making

DAPT Score ≥2: Continue DAPT beyond the initial period (prolonged therapy reduces net ischemic plus bleeding events compared to SAPT). 1

DAPT Score <2: Transition to SAPT (prolonged DAPT increases bleeding without reducing ischemic events, resulting in unfavorable benefit/risk ratio). 1

Additional Risk Assessment Tools

While the DAPT Score is the primary validated tool for this decision, also assess bleeding risk using established predictors 1:

For patients on oral anticoagulation: Use CHADS₂-VASc for ischemic risk and HAS-BLED for bleeding risk assessment. 1

Clinical Context for Score Application

Timing of Assessment

Apply the DAPT Score after patients have completed their mandatory initial DAPT period without significant bleeding or ischemic events 1:

• ACS patients: Assess after 12 months of DAPT 1
• Stable CAD patients: Assess after 1-6 months of DAPT 1

Disease-Specific Mandatory DAPT Duration (Before Score Application)

Acute Coronary Syndrome (NSTE-ACS or STEMI):

• Minimum 12 months of DAPT required regardless of stent type 1
• May shorten to 6 months in high bleeding risk patients 1

Stable/Chronic Coronary Syndrome:

• Default 1-6 months of DAPT after PCI-stenting 1
• High bleeding risk: 1-3 months minimum 1

Critical Caveats

The DAPT Score does NOT apply to:

• The initial mandatory DAPT period (it only guides decisions about prolonging therapy beyond this period) 1
• Patients who have already experienced bleeding or ischemic events during initial DAPT 1
• Patients requiring oral anticoagulation (different risk stratification applies) 1

High-risk scenarios that may warrant prolonged DAPT regardless of score:

• Prior stent thrombosis without correctable cause 1
• Complex PCI (left main stem, 2-stent bifurcation, suboptimal result) 1
• Lower extremity arterial disease 1

Transition to SAPT: Agent Selection

When transitioning from DAPT to SAPT after the initial period 1:

First-line options (equally recommended):

• Aspirin 75-100 mg daily 1
• Clopidogrel 75 mg daily (safe and effective alternative to aspirin) 1

The choice between aspirin and clopidogrel for long-term SAPT should be based on individual tolerability and prior adverse effects, as both have Class I, Level A recommendations for this indication. 1