LONDON -- There appears to be no advantage for continuing anticoagulation treatment after primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI), according to the results of a large randomized controlled trial presented at the European Society of Cardiology (ESC) Congress 2024 on August 31.

Updated data from the RIGHT trial showed that at 1 year, there is no difference between continued anticoagulation and no anticoagulation for either ischemic or bleeding outcomes.

The data also suggested that a difference across anticoagulants might exist at 30 days and at 1 year, findings that require confirmation in future studies.

The RIGHT study was undertaken to address an important gap in knowledge, explained the presenting study investigator Yan Yan, MD, an associate professor at Beijing Anzhen Hospital, Capital Medical University, Beijing, China.

"We know that postprocedural anticoagulation aims to prevent thrombotic or ischemic events after primary PCI," said Yan.

"Real-world studies gave us some suggestion that it is used frequently and may be associated with improved outcomes," she continued, adding that previously, "no randomized trial had investigated the effects of stopping or prolonging postprocedural anticoagulation in this kind of population."

This prior lack of trial data means that neither the European nor American guidelines for acute coronary syndromes currently provide a definitive recommendation as to whether anticoagulation should be discontinued after PCI for STEMI, Yan said.

The RIGHT study was an investigator-initiated trial led by researchers from the China Research Allies for Thrombosis & Embolism group in collaboration with experts from the ACTION Study Group in France. A total of 53 sites in China took part.

The objective was to demonstrate the superior efficacy and safety of using prolonged anticoagulation vs no anticoagulation after primary PCI for patients diagnosed with STEMI.

Yan reported that all the 2989 patients who participated in the trial had initially been treated with bivalirudin during and up to 4 hours after their procedures. The patients were then randomly allocated to either a "prolonged anticoagulation" group (n = 1494) or a "no anticoagulation" placebo group (n = 1495).

Those allocated to the prolonged anticoagulation group could receive one of three anticoagulant regimens as chosen by the participating center. These regimens were unfractionated heparin (UFH), given at an intravenous dose of 10 U/kg/h to maintain an activated clotting time between 150 and 220 seconds; low-molecular-weight heparin enoxaparin, given in one subcutaneous dose of 40 mg/d; or continued bivalirudin, given at an intravenous dose of 0.2 mg/kg/h.

There were two primary endpoints, one for efficacy and one for safety. The primary efficacy endpoint was the occurrence of a major adverse cardiovascular event (MACE) at 30 days, which was defined as a composite of all-cause death, nonfatal MI, nonfatal stroke, definite stent thrombosis, or need for urgent revascularization of any vessel. The primary safety endpoint was the occurrence of major bleeding at 30 days, defined as Bleeding Academic Research Consortium (BARC) types 3-5.

Secondary endpoints were MACE and major bleeding at 1 year and a comparison of the results according to the type of anticoagulation regimen used.

Yan said that the primary endpoint findings, MACE and BARC bleeding at 30 days, had previously been presented at the ESC Congress in 2023 and recently published in Circulation. These showed that MACE occurred in an equal percentage of patients in both the prolonged anticoagulation and no anticoagulation groups (both 2.5%; hazard ratio [HR], 1.0; P = .988). Major bleeding also occurred in similar percentages of patients in both the groups, at 0.5% vs 0.7%, respectively (HR = 0.74; P = .51).

Now reporting updated results, Yan said that 99.2% of patients completed 1 year of follow-up (1482 each in both groups). The percentage of patients experiencing MACE had increased to 4.2% in the prolonged anticoagulation group and to 4.9% in the no anticoagulation group, but the difference was nonsignificant (HR = 0.86; P = .38). Similarly, there was no difference between the groups in BARC 3-5 bleeding (HR = 0.87; P = .67).

Exploratory findings suggested that at both 30 days and 1 year, there might be a difference in MACE according to the anticoagulant regimen used. Of the 1494 patients in the prolonged anticoagulation group, 474 had been given enoxaparin, 510 UFH, and 510 bivalirudin. The cumulative incidence of MACE at 1 year was 47% (HR = 0.53; P = .38) lower with enoxaparin than with no anticoagulant use. There were no apparent differences, however, for UFH (HR = 1.08; P = .838) or bivalirudin (HR = 1.12; P = .68).

Yan reported that a network analysis found that there was heterogeneity among the anticoagulant regimens used, again with enoxaparin perhaps showing a benefit over the other two. This deserves confirmation in future studies, she suggested.

"I think it confirms that we're doing the right thing in stopping parenteral anticoagulation after primary PCI in STEMI patients, as it doesn't show benefit as routine therapy beyond that time," Róisín Colleran, MBBCh, PhD, an interventional cardiologist working for the Heart & Vascular Centre, Mater Private Network, in Dublin, Ireland, told Medscape Medical News.

Colleran, who was not involved in the trial, observed that "the recommendations are generally anticoagulation until revascularization, and at that time, we usually stop it."

With regards to differentiating between anticoagulants, she observed, "They have done a subgroup analysis for patients that were not randomized but were able to receive a protocol of one of the three [anticoagulants], and the enoxaparin seemed to show better results; but again, not randomized. So I don't know how balanced the baseline characteristics etc. were between medications, between groups."

Colleran also said, "Studies like this remind me of the [glycoprotein] GP IIb/IIIa inhibitor question, where we were using these and they were increasing bleeding rates, and in the end didn't really improve outcomes."

Also commenting on the findings for Medscape Medical News was Felice Gragnano, MD, PhD, assistant professor at University of Campania "Luigi Vanvitelli" and a consultant cardiologist at AORN S. Anna and S. Sebastiano in Caserta, Italy.

"If you have a successful PCI -- so you have resolved the thrombosis, and you have implanted your stent well, maybe with intravascular imaging -- then you are safe enough that you do not need an additional anticoagulation burden," Gragnano said ahead of Yan's presentation.

Remember that post-PCI, patients would be given dual antiplatelet therapy anyway, he added. "You start the dual antiplatelet therapy early, in the cath[eterization] lab[oratory], during the procedure or after it, and it will continue for a standard duration of 1 year.

"A hazard ratio of 1 means that you have the exact same rate of thrombotic events if you use the anticoagulation or not. So for this study at least, there is no sense to continue because you have no benefit."

The RIGHT study was supported by the Beijing Hospitals Authority Clinical Medicine Development of Special Funding and Jiangsu Hengrui Pharmaceuticals through a research grant to the Beijing United Heart Foundation. Yan reported no relevant conflicts of interest. Colleran and Gragnano were not involved in the study and reported no relevant financial relationships.