New risk score could aid decision making about extending dual antiplatelet therapy beyond 12 months

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Robert W Yeh (Boston, USA) told delegates at the 2015 American Heart Association (AHA) scientific sessions (7–11 November, Orlando, USA) that a new risk score—the dual antiplatelet therapy (DAPT) score—could be used to predict which patients may benefit from extending dual antiplatelet therapy beyond 12 months and which ones may be harmed from such an approach.

 

Yeh (Smith Center for Outcomes Research in Cardiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, USA) reported the 2014 DAPT (Dual antiplatelet therapy) study found that extending dual antiplatelet beyond 12 months in patients who have undergone percutaneous coronary intervention (PCI) with a drug-eluting stent both significantly reduces the risk of ischaemic events and significantly increases the risk of bleeding. He added that these findings indicate that the optimal duration of therapy may depend on the individual patient, commenting: “Individual patients may vary in terms of their expected benefits and risks of therapy.”


Therefore, Yeh and his fellow investigators developed the DAPT score to identify which patients would be likely to “derive benefit or harm from continuing dual antiplatelet therapy beyond one year—simultaneously accounting for the risks of ischaemia and for the risks of bleeding with continued therapy.” Using data from the DAPT study, focusing on the patients who did not have a major ischaemic or bleeding event within the first year of PCI, they identified patient characteristics that were associated with an increased risk of ischaemic events (eg. myocardial infarction) and also those that were associated with an increased risk bleeding. Yeh told Cardiovascular News: “Ischaemic risk was increased by comorbidities including diabetes, recent smoking, prior myocardial infarction or PCI, and congestive heart failure or low ejection fraction. Procedural factors, such as presentation with myocardial infarction at the index procedure, stent diameter <3mm, and PCI of a vein graft lesion, also predicted ischaemic risk. Bleeding was predicted by increasing age.”

He added that these characteristics were used to create two risk models—ischaemic and bleeding—that were integrated into a single score that could “estimate the overall expected benefit vs. harm of continuation of dual antiplatelet therapy for individual patients, after accounting for both ischaemic and bleeding risks.” However, according to Yeh, factors that were found to be predictive of both ischaemia and bleeding, such as chronic kidney disease and peripheral arterial disease, “fell out of the risk score because they do not actually help clinicians decide whether to continue or discontinue therapy”.


With the DAPT score, factors that increase the risk of ischaemic events are worth one point each except for vein graft PCI and congestive heart failure/low ejection fraction, which are two worth points each. However, minus points are awarded to factors that increase the risk of bleeding—for example, age 75 years or older is worth -2 points. A “high” DAPT score of ≥2 indicates that a patient might benefit from extending dual antiplatelet therapy beyond 12 months whereas as “low” score of


Yeh and colleagues used results from the DAPT study—excluding those of patients who received a paclitaxel-eluting stent—to show how the score performed in a randomised controlled trial. Yeh notes: “We also took the score and validated it within a separate study—PROTECT (Patient related outcomes with Endeavor versus Cypher stenting trial). In PROTECT, patients with a high DAPT score had a 50% increased risk ischaemic events compared with patients with a low DAPT score but also had a 30% lower risk of bleeding; just the type of patient who we would want to continue on dual antiplatelet therapy.”


He believes that the score could help to determine optimum duration of dual antiplatelet therapy in patients who have known risk factors for both ischaemic events and bleeding events, explaining: “There are patients at risk for both types of events, but they may be at higher risk of one event compared with the other. For example, an elderly patient with diabetes has an increased risk of ischaemic events because of their diabetes but they also have an increased risk of bleeding events because of their age. If diabetes and age are their only risk factors, they would have a DAPT score of -1 and, therefore, the recommendation would be to not continue therapy beyond 12 months.  In such a patient, the risk of bleeding associated with their age outweighs the risk of ischaemic events associated with their diabetes].”


In terms of further data for the score, Yeh says he and his fellow investigators are currently “working on” determining if the score could identify the risk and benefits of dual antiplatelet therapy during the first 12 months after PCI. “But for patients reaching a year after PCI without a major event, I think the score is ready to be used straight away,” he adds, noting that these patients constitute the vast majority of patients undergoing PCI.


Concluding his presentation at the AHA, Yeh said: “Among patients who have not had a major ischaemic or bleeding event within the first year after PCI, the DAPT score identified patients for whom ischaemic benefits outweighed bleeding risks and patients for whom bleeding risks outweighed ischaemic benefits. The DAPT score may help clinicians decide who should and who should not be treated with extended duration of dual antiplatelet therapy.”


The DAPT score calculator is now available via the DAPT study website.

ACC/MedPage Today Video interview between Peter Block and Robert Yeh about the DAPT score.

 

 

 

 

 

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