A dual antiplatelet therapy (DAPT) score improved the prediction of patient benefit and harm from continued DAPT beyond the assessment of myocardial infarction (MI) history, according to data published in the Journal of the American College of Cardiology.
In addition, patients with a previous MI were found to have a greater risk of having late ischemic events than those with no MI history.
Results of the original DAPT study showed that patients who received continued thienopyridine and aspirin after 12 months had lower ischemic risk but higher bleeding risk than those who were treated with placebo and aspirin.
The DAPT score was developed to determine among the patients eligible for long-term DAPT those who would be more likely to derive benefit vs harm from long-term therapy. Researchers sought to determine whether the DAPT score decision tool could aid prescriptions of DAPT duration in patients with or without prior MI treated with coronary stents.
The score ranges from -2 to 10, and incorporates several variables including age, smoking status, diabetes, MI history, prior coronary interventions, stent type and diameter, heart failure, and left ventricular ejection fraction. Lower scores were associated with higher bleeding risk, with or without continued thienopyridine therapy, and less ischemic benefit.
“The DAPT score may be useful in assessing the risks and benefits of continuing dual antiplatelet therapy for more than 12 months after coronary stenting,” the authors wrote. “Among the additional factors to consider are medication compliance and the occurrence of major ischemic or bleeding events during the initial treatment period.”
In this sub-analysis, patients from the DAPT study were categorized into 2 groups depending on MI history. Patients with any history of MI (n=5340) were more likely to smoke and be male, while patients with no prior MI (n=6308) were more likely to have diabetes, congestive heart failure, or hypertension.
During the follow-up period, 3.8% of patients with prior MI experienced an additional MI, compared with 2.4% of patients with no prior MI (P=.01). Prolonged thienopyridine reduced late MI compared with placebo among patients with prior MI (hazard ratio [HR] for all MI: 0.46; P<.001) and among those with no prior history (HR: 0.60; P=.003). Thienopyridine also increased bleeding in both groups (HR for any MI: 1.86, P=.01; HR for no MI: 1.58, P=.01).
A DAPT score ≥2 was associated with reduction in MI or stent thrombosis with continued thienopyridine compared with placebo (2.7% vs 6.0%; P<.001 for any MI; 2.6% vs 5.2%; P=.002 for no MI) with comparable bleeding rates. In patients who had scores<2 in both groups, continued thienopyridine was associated with increased bleeding risk, but similar rates of ischemia.
“Patients with any MI have an increased risk for ischemic events 12 to 30 months after PCI compared with patients with no MI despite treatment with DAPT [dual antiplatelet therapy],” the authors wrote. “Prolonged (>12 months) thienopyridine therapy provides a greater absolute reduction in ischemic events with a similar relative bleeding risk among patients with (vs without) any MI.”
Kereiakes DJ, Yeh RW, Massaro JM, et al. DAPT score utility for risk prediction in patients with or without previous myocardial infarction. J Am Coll Cardiol. 2016;67(21):2492-2502. doi: 10.1016/j.jacc.2016.03.485.