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APRIL 03, 2020 -- The VOYAGER PAD results from more than 6,500 patients created the biggest evidence base by far ever collected from patients with symptomatic peripheral artery disease (PAD) who underwent a vascular intervention, and showed that the combination of twice-daily rivaroxaban and once-daily aspirin was safe and more effective than aspirin alone for reducing future thrombotic and ischemic events.
Following that report on March 28, a prespecified subgroup analysis presented the next day showed that adding clopidogrel to this two-drug combination produced no added efficacy but caused additional bleeding episodes, suggesting that the common practice of using clopidogrel plus aspirin in these patients, especially those who receive a stent in a peripheral artery, should either fall by the wayside or be used very briefly.
"In the absence of clear benefit, clopidogrel exposure along with aspirin and rivaroxaban should be minimized or avoided to reduce this risk," William R. Hiatt, MD, said at the joint scientific sessions of the American College of Cardiology and the World Heart Federation. The meeting was conducted online after its cancellation because of the COVID-19 pandemic. But he also cautioned that "we did not control for clopidogrel use, and so the patients who received clopidogrel look different [from patients who did not receive clopidogrel]. We must be cautious in interpreting differences between patients on or off clopidogrel," warned Dr. Hiatt, a lead investigator for VOYAGER PAD, professor for cardiovascular research at the University of Colorado at Denver in Aurora and president of the affiliated Colorado Prevention Center.
In addition to this substantial caveat, the finding that clopidogrel appeared to add no extra benefit to the rivaroxaban/aspirin regimen "contradicts some dogmas that have been in the field for decades," Dr. Hiatt said. Use of dual-antiplatelet therapy (DAPT), in this setting usually aspirin and clopidogrel, in patients who have just undergone lower-extremity revascularization is "current dogma," even though it is not based on any direct evidence for efficacy, but instead came on the scene as "an extrapolation from the coronary artery literature, where it does have some benefit, particularly after percutaneous coronary intervention," he explained.
The only reported study results to examine use of DAPT in patients who underwent peripheral artery revascularization focused entirely on patients who had a surgical procedure and showed no added benefit from DAPT over aspirin only in a multicenter, randomized trial with 851 patients (J Vasc Surg. 2010 Oct;52:825-33), Dr. Hiatt noted. In VOYAGER PAD, two-thirds of all patients underwent an endovascular, not surgical, peripheral intervention, and among those treated with clopidogrel, 91% had endovascular treatment.
"We're not saying don't use DAPT, but patients on three drugs are at higher bleeding risk than patients on two drugs. I think our data also suggest starting rivaroxaban immediately after a procedure [as was done in VOYAGER PAD], and not waiting to complete a course of DAPT," Dr. Hiatt said.
Other experts embraced Dr. Hiatt's take on these findings, while warning that it may take some time for the message to penetrate into practice.
The overall VOYAGER PAD results "are practice changing for vascular interventions; it was by an order of magnitude the largest vascular intervention trial ever conducted," commented Sahil A. Parikh, MD, a designated discussant, interventional cardiologist, and director of endovascular services at New York–Presbyterian Medical Center. "The data suggest that the value of clopidogrel is questionable, but the added hazard is not questionable" when given to patients on top of rivaroxaban and aspirin. The results "certainly beg the question of whether one should use DAPT at all, and if so, for how long."
Use of DAPT in patients undergoing peripheral revascularization, especially patients receiving a stent, has been "dogma," Dr. Parikh agreed. "It's been pounded into our heads that DAPT is standard care, so it will take some time to penetrate into the practicing community."
"Could there be patients who could benefit from triple therapy? That's possible, but it needs testing," commented Mark A. Creager, MD, professor of medicine and director of the Heart and Vascular Center at Dartmouth-Hitchcock Medical Center in Lebanon, N.H. "We've made terrific strides with the results from VOYAGER PAD," and from the earlier COMPASS trial, which proved the benefit of rivaroxaban and aspirin in patients with stable atherosclerotic vascular disease including many PAD patients (N Engl J Med. 2017 Oct 5;377:1319-30). Use of rivaroxaban and aspirin in PAD patients based on the COMPASS results "is beginning to make an impact, but has a long way to go," Dr. Creager said in an interview.
In late 2018, the Food and Drug Administration gave rivaroxaban a revised labeling that included an indication for patients with PAD based on the COMPASS findings. The VOYAGER PAD and COMPASS trials are especially noteworthy because "they opened a whole area [of study] in patients with peripheral vascular disease, " he added.
The prespecified analysis that Dr. Hiatt reported analyzed outcomes among the 51% of patients enrolled in VOYAGER PAD (Vascular Outcomes Study of Acetylsalicylic Acid Along With Rivaroxaban in Endovascular or Surgical Limb Revascularization for Peripheral Artery Disease) who received clopidogrel during follow-up at the discretion of their treating physician and the outcomes among the remainder who did not. The two subgroups showed several statistically significant differences in the prevalence of various comorbidities and in some baseline demographic and clinical metrics, and the analyses that Dr. Hiatt reported did not attempt to correct for these differences. Patients who received clopidogrel had the drug on board for a median of 29 days, and about 58% received it for 30 days or less.
The main finding of his analysis was that "adding clopidogrel did not modify benefit at all" from the perspective of the primary endpoint of VOYAGER PAD, the incidence of a five-item list of adverse events (acute limb ischemia, major amputation for vascular cause, myocardial infarction, ischemic stroke, and cardiovascular death) during a median follow-up of 28 months (N Engl J Med. 2020 Mar 28. doi: 10.1056/NEJMoa2000052), said Dr. Hiatt. Among patients on clopidogrel, those treated with both rivaroxaban and aspirin had a 16.0% incidence of the primary endpoint, compared with an 18.3% rate among patients on aspirin only, for a 15% relative risk reduction, identical to the study's primary result. Among patients not on clopidogrel, the primary endpoint occurred in 18.7% of patients on rivaroxaban plus aspirin and in 21.5% of those on aspirin only, a 14% relative risk reduction. The analyses also showed that adding clopidogrel appeared to increase the rate of bleeding episodes, particularly the incidence of major bleeds by the criteria of the International Society on Thrombosis and Haemostasis (ISTH), which rose among patients on aspirin alone from 3.3% without clopidogrel treatment to 4.9% with clopidogrel, and in patients on rivaroxaban plus aspirin these major bleeds increased from 5.4% with no clopidogrel to 6.5% with clopidogrel.
An especially revealing further analysis showed that, among those who also received rivaroxaban and aspirin, clopidogrel treatment for more than 30 days led to substantially more bleeding problems, compared with patients who received the drug for 30 days or less. Patients who received clopidogrel for more than 30 days as part of a triple-drug regimen had a 3.0% rate of major ISTH bleeds during 180 days of follow-up, compared with a 0.9% rate for patients in the aspirin-alone group who also received clopidogrel, a 2.1% between-group difference. In contrast, the difference in major ISTH bleeds between the two treatment arms in the subgroup who received clopidogrel for 30 days or less was 0.7%.
"What's inarguable is that the course of clopidogrel should be as short as possible, probably not more than 30 days unless there is a real extenuating rationale," commented designated discussant Gregory Piazza, MD, a cardiologist at Brigham and Women's Hospital in Boston.
VOYAGER PAD was sponsored by Bayer and Janssen, the companies that market rivaroxaban (Xarelto). The institution that Dr. Hiatt leads has received research funding from Bayer and Janssen and from Amgen. Dr. Parikh has been a consultant to Terumo; has received research funding from Shockwave, Surmodics, and Trireme; has worked on trial monitoring for Boston Scientific and Silk Road; and has had other financial relationships with Abbott, Boston Scientific, and Medtronic. Dr. Creager had no disclosures. Dr. Piazza has received research grants from Bayer and Janssen, as well as Bristol-Myers Squibb, Diiachi, EKOS, and Portola, and he has been a consultant to Optum, Pfizer, and Thrombolex.