Of two multicenter, randomized trials to address this question it is the larger, according to Rania Hammami, MD, who presented the results at the Transcatheter Cardiovascular Therapeutics annual meeting.
In the open-label RIVARAD trial, 538 patients were randomized to 10 mg rivaroxaban or standard care alone. Standard care at the beginning of the procedure included unfractionated heparin in a dose of 50 IU/kg for angiography and up to 100 IU/kg for PCI. Manual compression was applied at the end of the procedure followed by an evaluation for complications, such as hematoma or aneurysm.
For the primary outcome of radial access occlusion at 30 days, the lower rate in the rivaroxaban arm (6.9% vs. 13.0%) translated into a statistically significant 50% reduction (odds ratio, 0.50; P = .011).
Rivaroxaban Preserves Radial Pulse
Rivaroxaban was also favored for the endpoint of inability at 30 days to find a radial pulse (5.8% vs. 12.2%; P = .01). Interestingly, there was some disparity for this endpoint for clinical examination and ultrasound.
"In 12 patients, we were able to palpate a radial pulse, but the ultrasound showed an occlusion of the vessel, while in 7 patients we could not find a radial pulse even though the radial artery was patent on ultrasound," Hammami, of the department of cardiology, Hedi Chaker Hospital, Sfax, Tunisia, said at the meeting, sponsored by the Cardiovascular Research Foundation.
The incidence of hemorrhagic complications was higher in the rivaroxaban group (2.7% vs. 1.9%), but the difference did not approach statistical significance (OR, 1.5; P = .54). Moreover, all of the bleeding complications were minor (Bleeding Academic Research Consortium level 1), and none of the bleeding complications were observed in patients receiving rivaroxaban alone. Rather, all patients with bleeding were taking one or more antiplatelet drugs along with rivaroxaban.
On univariate analysis, several baseline characteristics were associated with subsequent radial occlusion, including female sex (P = .02), current smoking (P = .03), renal failure (P = .004), and PCI for acute coronary syndrome (P = .02). On multivariate analysis, female sex (P = .001) and current smoking (P < .0001) became even stronger predictors of occlusion on a statistical basis, while a prior procedure involving radial access was also a significant predictor (P = .029).
"One woman out of two developed radial access occlusion if she had a history of smoking and had a history of a transradial puncture," Hammami reported.
In a subgroup analysis, relative protection from radial artery occlusion from a 7-day course of rivaroxaban was particularly pronounced in those with diabetes, renal failure, or hypertension relative to those without these conditions, but the protective effect appeared to be about the same regardless of body mass index, age, sheath size, or current use of statins.
These findings are consistent with other studies evaluating the risk of radial access occlusion, according to Hammami. While different studies she cited reported incidences ranging from less than 1% to more than 30%, the risk has typically been highest in populations with increased susceptibility for thrombus formation, such as smokers and patients with diabetes.
Preventing radial artery occlusion has several benefits, not least of which is preserving this access point for future interventions, according to Hammami.
RIVARAD is the largest study to evaluate an anticoagulant for the prevention of radial artery occlusion, but it is not the first. Earlier in 2022, a Chinese trial called RESTORE was published in Circulation: Cardiovascular Interventions. In that placebo-controlled study of 382 patients, 7 days of 10 mg rivaroxaban was also linked to a significant reduction in radial artery occlusion at 30 days (3.8% vs. 11.5%; P = .011).
"We don't know if a higher dose of rivaroxaban would be more effective and equally safe," said Hammami, but added that a Canadian trial called CAPITAL RAPTOR will test this premise. In this trial, there is a planned enrollment of 1,800 patients who will be randomized to 15 mg rivaroxaban or standard treatment.
Occlusion Risk Appears Underappreciated
The risk of radial artery occlusion might be underappreciated. According to data cited by Hammami, only about half of interventionalists in the United States and fewer than 10% outside of the United States routinely assess radial artery patency in conjunction with radial-access PCI. The data from this trial suggest that the risk can be substantially reduced, particularly in high-risk patients, with anticoagulant therapy.
Agreeing that this is a potentially avoidable complication, Roxanna Mehran, MD, director of interventional cardiovascular research and clinical trials, Icahn School of Medicine at Mount Sinai, New York, called the RIVARAD study "a clinically meaningful trial," and valuable for identifying risk factors as well as for showing a treatment effect and acceptable safety from a short course of a factor Xa inhibitor.
"This is very important work," said Mehran, who praised the quality of the study and the contribution it makes for considering how and when prophylaxis is needed.