Individualize DAPT duration based on risk/benefit profile, says expert
The duration of dual antiplatelet therapy (DAPT) should be individualized based on ischaemic and bleeding risk of a particular patient, rather than focusing on a dualistic short- vs long-duration therapy thinking, advocates a leading expert during AFCC 2018.
“It is time to end the dualistic short vs long duration of DAPT debates,” according to Professor Glenn Levine of Baylor College of Medicine in Houston, Texas, US. The dualistic short vs long debate also disregards the fact that many patients whose risk of ischaemia is comparable to their risk of bleeding may best be treated by standard-duration DAPT. [Circulation 2017;135:2451-2453]
“Rather, it is time to acknowledge that some patients may best be treated with a short duration of DAPT, some with a standard duration of DAPT, and some with a longer or prolonged duration of DAPT. We should now direct our energies toward identifying these subgroups,” he added.
Who and how to treat?
“Decisions on DAPT duration for any individual patient must be based [on] informed ongoing assessment of the benefits and risks of DAPT for that particular patient, as well as patient preference,” Levine stated.
“All patients are not the same!” he stressed, pointing out that the spectrum of ischaemic and bleeding risk ranges widely at the individual patient level, with a five- to eightfold difference in thrombotic risk between low-risk and high-risk patients as shown in the PARIS Registry. Likewise, the predicted risk of bleeding over several years can vary fourfold between patients with low vs high calculated bleeding risk. [J Am Coll Cardiol 2016;67:2224-2234]
In terms of patient selection, prolonged DAPT beyond 1 year after PCI was associated with more benefit than risk in high-risk patients (DAPT score ≥2), who had 8.2 times greater reduction in thrombotic events relative to increase in bleeding events in the DAPT study. In contrast, patients with a low DAPT score (<2) had a 2.4 times greater increase in bleeding events than reduction in thrombotic events. [JAMA 2016;315:1735-1749]
In assessing benefit/risk balance of a patient, tools such as DAPT score, PARIS Registry score, and PRECISE-DAPT score can help physicians to individualize care when making decision on DAPT duration. [J Am Coll Cardiol 2016;67:2224-2234; JAMA 2016;315:1735-1749; Lancet 2017;389:1025-1034]
“[However,] no single analysis/risk score is ideal and covers all risk factors and clinical settings,” said Levine, noting that these risk scores have only moderate level of discrimination, as indicated by a “c statistics” of approximately 0.65. Also, most of the prediction rules were based on studies on clopidogrel, with little data with ticagrelor or prasugrel. There is also no risk score that incorporates myocardial territory at risk, such as small obtuse marginal branch vs proximal left anterior descending artery, according to Levine.
Nonetheless, the risk scores represent important steps toward individualizing care that is based on benefit/risk profile of a patient, he said.
For patients with ACS/PCI and AF in whom triple antithrombotic therapy is indicated, Levine suggested that triple therapy should be kept as short as possible (1-6 months). Noting that double therapy (oral anticoagulant plus single antiplatelet therapy) can lead to less bleeding than full dose triple therapy, Levine said, “use of double therapy seems reasonable, if not preferred in high bleeding risk patients, and likely seems reasonable in average bleeding risk patients.”
“In many patients treated with oral anticoagulant therapy, consider stopping all antiplatelet therapy 1 year after an ACS or PCI,” he advised.