DAPT Score Utility for Risk Prediction in Patients With or Without Previous Myocardial Infarction

Background: The DAPT (Dual Antiplatelet Therapy) study enrolled patients after coronary stenting. Patients randomized to continued thienopyridine and aspirin after 12 months had lower ischemic risk but higher bleeding risk than those treated with placebo and aspirin.

Objectives: This study sought to determine whether a decision tool (DAPT score) aids prescription of dual antiplatelet therapy duration in patients with or without prior myocardial infarction (MI) treated with coronary stents.

Methods: Patients were categorized according to any history of MI before the index procedure or no history of MI. Risk differences during the randomized treatment period (12 to 30 months) for ischemic (MI and/or stent thrombosis) and bleeding (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Arteries moderate/severe) events were compared according to DAPT score.

Results: Rates of MI were 3.8% versus 2.4% (p = 0.01) for patients with any MI versus no MI. Continued thienopyridine reduced late MI compared with placebo regardless of MI history (hazard ratio [HR] for any MI: 0.46; p < 0.001; HR for no MI: 0.60; p = 0.003) and increased bleeding (HR: 1.86, p = 0.01 any MI; HR: 1.58, p = 0.01 no MI). DAPT scores ≥2 were associated with reductions in MI/stent thrombosis with continued thienopyridine compared with placebo (2.7% vs. 6.0%, p < 0.001 any MI; 2.6% vs. 5.2%, p = 0.002 no MI), with comparable bleeding rates. Among patients with DAPT scores <2 in both groups, continued thienopyridine was associated with significantly increased bleeding but similar rates of ischemia.

Conclusions: Patients with previous MI have greater risk of late ischemic events than those with no MI history. The DAPT score improves prediction of patient benefit and harm from continued dual antiplatelet therapy beyond assessment of MI history alone. (The Dual Antiplatelet Therapy Study; NCT00977938).