Better tools are needed to identify patients most likely to benefit from extending DAPT beyond 12 months following coronary stenting, said researchers presenting findings from a nationwide study showing the DAPT score did not adequately discriminate ischemic and bleeding risk. The study was presented Aug. 26 at ESC Congress 2018 and simultaneously published in the Journal of the American College of Cardiology.

Researchers followed 41,101 patients from Sweden who had undergone 12 months of event-free DAPT post-stenting for an additional 18 months. They compared risk of myocardial infarction (MI) or stent thrombosis, major adverse cardiovascular and cerebrovascular events (MACCE), and fatal or major bleeding according to the DAPT score.

Based on their comparisons, the DAPT score had a discrimination of 0.58 for MI or stent thrombosis, 0.54 for MACCE, and 0.49 for fatal or major bleeding. Additionally, risk of MI or stent thrombosis was significantly greater in patients with DAPT scores of ≥3. Researchers noted MACCE risk "followed a J-shaped pattern" and increased at DAPT scores of ≥4. Absolute differences in fatal or major bleeding risk were small between scores and event rates of ischemic outcomes were comparable. However, "fatal or major bleeding rates were approximately half of those in the placebo-arm of the DAPT Study, from which the score was derived," researchers said.

Overall, the findings indicate the relationship between score and ischemic risk do not correspond to the suggested decision rule for extended DAPT in patients with scores of 2 or higher. While the score may still help identify patients at high ischemic risk, researchers suggest that "the score and its decision rule may not be generalizable to real-world populations" and additional tools are needed.

"The DAPT score joins a plethora of statistical models that have uncertain utility," writes John A. Bittl, MD, FACC, in a related editorial comment. "Ueda et al., are commended for their exemplary analysis, which is a reminder that clinical decision rules must be held to a high standard. Doctors should rest assured that even the best mathematical models and prediction rules cannot replace clinical judgment."

Clinical Topics: Anticoagulation Management, Cardiovascular Care Team

Keywords: ESC18, ESC Congress, Platelet Aggregation Inhibitors, Myocardial Infarction, Risk, Thrombosis, Anticoagulants

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