Patients who receive a stent to open a narrowed or blocked coronary artery may need to keep taking aspirin and clopidogrel together — a regimen known as dual antiplatelet therapy — even a year after the procedure, according to a new study.
Severance Hospital said on the 4th that a joint research team of cardiology professors Kim Byeong-keuk, Lee Seung-jun and Lee Yong-joon found the association after comparing two antiplatelet strategies in patients who remained at high risk of ischemic events one year after stenting.
Patients who undergo a procedure to widen a narrowed coronary artery with a stent must take aspirin and clopidogrel together for a set period to prevent blood clots and heart attacks. In most cases, they switch to a single drug six to 12 months after the procedure to reduce the risk of bleeding.
Whether that same rule should apply to patients with risk factors — a history of acute coronary syndrome, diabetes, chronic kidney disease or complex coronary lesions — has been a matter of dispute. Such high-risk patients face a relatively higher chance of heart attack and stroke even a year after the procedure. The dilemma is that staying on both drugs can lower cardiovascular risk but raise the risk of bleeding.
The team followed 3,203 high-risk patients at 19 medical institutions in South Korea for two years, all of them at least one year past treatment with a drug-eluting stent, which is coated with medication that prevents the vessel from narrowing again. Of those, 1,601 were assigned to clopidogrel alone and 1,602 to clopidogrel plus aspirin. The design extended dual antiplatelet therapy by an additional year beyond the conventional period to see how it affected outcomes.
The combined rate of clinical events — ischemic events such as stroke and heart attack plus bleeding — showed no meaningful difference, at 5.0% for the single-drug group and 5.1% for the dual-therapy group. Separating ischemic events from bleeding, however, revealed a clear gap between the two strategies.
Major ischemic events — death, heart attack, stent thrombosis and stroke combined — occurred in 3.7% of the clopidogrel-only group, 2.33 times the rate in the dual-therapy group at 1.6%. Bleeding severe enough to require treatment, by contrast, occurred in 1.8% of the clopidogrel-only group and 4.1% of the dual-therapy group. Taking clopidogrel alone carried a 57% lower risk of bleeding than taking both drugs.
The findings mean no single strategy can be declared better for all high-risk patients and that treatment must be tailored to each patient's risk profile. Where the risk of ischemic events such as heart attack is greater, dual therapy can be extended; where the bleeding risk is greater, a switch to a single drug after one year can be considered.
"Rather than uniformly switching to a single drug one year after stenting, treatment should be decided by weighing each patient's ischemic and bleeding risks," Kim said. "We need to establish criteria that can predict individual risk more precisely."
The findings were presented in a Hot Line session for major clinical trials at the ESC Congress 2026, held recently in Munich, Germany, and published the same day in the New England Journal of Medicine.
