RIVAWAR: Rivaroxaban as Safe and Effective as Warfarin for LV Thrombus in MI

CHICAGO, IL—Patients who develop thrombus in the left ventricle following myocardial infarction fare equally well when treated with rivaroxaban (Xarelto; Bayer/Janssen) as they do with warfarin, the new RIVAWAR study shows. Both treatments result in clot resolution by 3 months.

With its easier dosing regimen, rivaroxaban is a “viable alternative” to warfarin in these patients as it eliminates the need for routine monitoring, researchers said this week at the American College of Cardiology 2025 Scientific Session where the results were presented.

“It’s just simply an easier medication to give,” lead investigator Jehangir Ali Shah, MBBS (National Institute of Cardiovascular Diseases, Karachi, Pakistan), told TCTMD. “You don’t need to monitor blood samples. You don’t need to monitor other drugs or food because there are a lot of food-drug interactions with warfarin.”

Thomas Lüscher, MD (Royal Brompton and Harefield Hospitals, London, England), who commented on the results following the late-breaking clinical trial presentation, said that since the introduction of primary PCI and adjunctive antithrombotic medications, the development of thrombus in the LV is less of a problem. Nonetheless, it remains an important consideration after STEMI given the subsequent risks.  

“It’s a decreasing population, fortunately, but an important one because these patients [can] have a stroke after they suffered a severe myocardial infarction,” said Lüscher.

While the overall incidence of LV thrombus formation is estimated to be under 3% for all STEMI patients, it remains around 9% for patients with anterior STEMI. Anticoagulation with warfarin is recommended for these patients, the goal being to resolve the thrombus and reduce the subsequent risk of embolic events.

‘Pop-and-Go’ Strategy

The single-center, open-label RIVAWAR study randomized 261 patients (mean age 54.5 years; 20.7% female) diagnosed with LV thrombus within 7 days of STEMI/NSTEMI to rivaroxaban or warfarin for 12 weeks. Echocardiographic follow-up was performed at 4 and 12 weeks. More than 90% of patients presented with STEMI. In total, 85% of patients underwent PCI and 90% were randomized within 2 days of their event.   

At 4 weeks, the thrombus was resolved in 20.1% of patients treated with rivaroxaban and 8.3% of those treated with warfarin (OR 2.41; 95% CI 1.05-2.46). By 12 weeks, thrombus resolution was achieved in 95.8% and 96.6% of patients in the rivaroxaban and warfarin arms, respectively, falling within the bounds of the noninferiority margin of 7% (OR 0.98; 95% CI 0.74-1.29).

The results, said Shah, should be a “game changer” given the ease of using the direct oral anticoagulant. Anna Bortnick, MD (Albert Einstein College of Medicine, Bronx, NY), agreed, telling the media in an ACC press conference that rivaroxaban is a “pop-and-go” strategy as opposed to the challenges with warfarin.

There was no difference between the two options in safety as assessed by all-cause mortality, major bleeding, or ischemic stroke. During the Main Arena discussion, Lüscher noted that there were six ischemic strokes among the rivaroxaban-treated patients versus one in the warfarin group, but Shah said the difference wasn’t statistically significant and numbers were small. The group plans to perform a larger study to confirm the results in RIVAWAR.