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Dr. Dimitri Richter
In the era of extended DAPT treatment the eternal question is how long is long enough without significantly increasing the risk of bleeding?
This question is not easy to answer and all trials and registries performed are used in order to create the “best” possible score to help everyday clinicians to be able to predict a bleeding or ischemic event.
The PRECISE-DAPT score was introduced in the latest 2017 Focused update on Dual Antiplatelet Therapy in an attempt to improve the previous DAPT score.
The DAPT score was developed from 11 648 patients enrolled in the DAPT trial and was initially validated in 8136 patients enrolled in the PROTECT trial.
This prediction rule identified nine factors [age, congestive heart failure/low left ventricular ejection fraction (LVEF), vein graft stenting, MI at presentation, prior MI or PCI, diabetes, stent diameter <3 mm, smoking, and paclitaxel-eluting stent] resulting in a score ranging from −2 to + 10. Within the DAPT trial, a high-risk score (i.e. a score ≥2) selected patients who showed a reduction in MI/stent thrombosis and cardiovascular or cerebrovascular events risk [ (NNT) for benefit for ischaemic event reduction = 34] after a prolonged, 30-month DAPT, with only a modest increase in bleeding risk (NNT for harm = 272). In turn, a low-risk score (<2) selected patients recruited in the DAPT trial who did not derive any reduction of ischaemic events from prolonging DAPT, with a significant increase in moderate/major bleeding (NNT for harm = 64). As DAPT duration was not randomized in the PROTECT trial, the value of the DAPT score in guiding the duration of therapy has so far only been shown for patients recruited to the DAPT trial.
Two independent predictive scores for bleeding [age, body mass index, smoking, anaemia, creatinine clearance (CrCl), and triple therapy at discharge] and MI or stent thrombosis [diabetes mellitus, ACS, smoking, CrCl, prior PCI, and prior coronary artery bypass graft surgery (CABG)] have also been developed from the Patterns of Nonadherence to Antiplatelet Regimens in Stented Patients (PARIS) registry. PARIS was a prospective, multicentre, observational study of patients undergoing PCI with stent implantation, which was designed to examine the different modes of DAPT cessation and to investigate the influence of these modes on subsequent clinical adverse events. This registry study included patients with an indication for oral anticoagulation. The value of the PARIS bleeding and/or ischaemic risk scores to tailor DAPT duration remains unclear, since therapy duration was not randomized in the PARIS study and no study to date has applied the results of these scores for DAPT type or duration guidance. A high ischaemic risk status was observed in roughly 40% of high bleeding risk patients and as many as 65.3% presented low ischaemic and bleeding risks.
Therefore, it remains unclear how DAPT duration should be guided by the simultaneous assessment of ischaemic and bleeding risk features according to PARIS.The PRECISE-DAPT (PREdicting bleeding Complications In patients undergoing Stent implantation and subsEquent Dual Anti Platelet Therapy) collaborative study included a total of 14 963 patients with CAD who underwent elective, urgent, or emergent PCI and generated a five-item (age, CrCl, haemoglobin, white blood cell count, and prior spontaneous bleeding) prediction algorithm for out-of-hospital bleeding in patients treated with DAPT.
The predictive performance of this novel score was assessed in the derivation cohort and validated in 8595 and 6172 patients treated with PCI from the PLATelet inhibition and patient Outcomes (PLATO) trial and the Bern PCI registry, respectively. The PRECISE-DAPT score showed improved integrated discrimination and reclassification performance as compared to the PARIS bleeding score in both validation cohorts. The usefulness of this score was also assessed within patients randomized to different DAPT durations to identify the effect on bleeding and ischaemia of a long (12–24 months) or short (3–6 months) treatment duration in relation to baseline bleeding risk. It was observed that among patients deemed at high bleeding risk based on PRECISE-DAPT (PRECISE-DAPT score ≥25), prolonged DAPT was associated with no ischaemic benefit but a remarkable bleeding burden leading to an NNT for harm of 38. On the other hand, longer treatment in patients without high bleeding risk (PRECISE-DAPT score <25) was associated with no increase in bleeding and a significant reduction in the composite ischaemic endpoint of MI, definite stent thrombosis, stroke, and target vessel revascularization, with an NNT for benefit of 65. Selecting a shorter than 12-month treatment duration in patients deemed at high bleeding risk upfront may therefore prevent their exposure to an excessive bleeding hazard. In turn, patients at non-high bleeding risk might receive a standard (i.e. 12 months) or prolonged (i.e. >12 months) course of treatment if tolerated.
However, none of these risk prediction models have been prospectively tested in the setting of RCTs. Therefore, their value in improving patient outcomes remains unclear.Strengths & Weaknesses
The strength of the DAPT score is that it predicts both ischemia and bleeding so that an overall assessment can be made to tailor antiplatelet therapy. The weakness is that it is based on a cohort of “uneventful” patients finishing a year of DAPT therapy so it is not relevant in the early post-PCI period. Also, the DAPT cohort included many patients receiving early generation DES (including about a quarter with paclitaxel eluting stents) and about a seventh with bare metal stent; and the C-index is relatively low in the external validation cohort.
Given that the DAPT cohort differs from the PRECISE-DAPT cohort in that patients had no bleeding in the first year on DAPT, it is no surprise that neither previous bleeding nor low haemoglobin (2 of the 5 PRECISE-DAPT factors) is present in the DAPT score. On the contrary, age is included in both scores and treated in somewhat similar manner-a 3-level parameter in DAPT (0 for age <65, -1 for age 65 to <75, -2 for age >75) and a continuous parameter from 50 to 90 years in PRECISE-DAPT.
The PRECISE-DAPT score is not a one-off score. It needs to be reevaluated periodically to each patient since the variables can change significantly over time and at each visit of a patient with extended DAPT treatment we need to re-evaluate it and use clinical judgment for the final decision.
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