Key Points:
- Left ventricular thrombus (LVT) is a serious complication following heart attacks, particularly STEMIs, and can lead to systemic embolism or stroke.
- Warfarin has traditionally been the recommended therapy for treating LVT in patients post-STEMI.
- The RIVAWAR trial demonstrated that rivaroxaban was comparable to warfarin in achieving clot resolution at three months, providing a safer, more convenient alternative without the need for regular blood tests.
Following a heart attack, particularly an ST elevation myocardial infarction (STEMI), patients may develop left ventricular thrombus (LVT), a potentially fatal condition in which blood clots form in the heart’s main pumping chamber. These clots can embolize to other organs, causing strokes or ischemia in the heart, lungs, kidneys, liver, or limbs. Effective treatment of LVT is critical to prevent these complications, and warfarin has been the standard therapy of choice. However, warfarin requires frequent blood tests to monitor clotting time, and it can interact with foods and other medications, raising concerns over its safety and convenience.
The RIVAWAR trial, presented at the American College of Cardiology’s Annual Scientific Session (ACC.25), compared rivaroxaban, a direct oral anticoagulant, to warfarin in post-heart attack patients with LVT. Dr. Jehangir Ali Shah, an associate professor at the National Institute of Cardiovascular Diseases in Karachi, Pakistan, led the study. Shah and colleagues aimed to determine whether rivaroxaban could offer similar efficacy to warfarin but with fewer monitoring requirements and a more predictable pharmacokinetic profile.
This open-label study enrolled 261 patients (average age 55 years, 80% male, 94% with LV ejection fraction <50%) with STEMI and LVT. Patients were randomized to receive either rivaroxaban or warfarin for a treatment period of three months. The primary endpoint was complete dissolution of the left ventricular clot at one and three months, assessed by echocardiogram, while secondary endpoints included all-cause mortality, stroke, and major bleeding events.
At one month, rivaroxaban outperformed warfarin, with 20.1% of patients achieving complete clot resolution compared to 8.3% in the warfarin group ( (risk difference 11.8%; 95% CI 1.2-2.2; OR 2.41; 95% CI 1.05-2.46; p=0.017). By three months, both treatments showed comparable results in clot resolution, with 95.8% of the rivaroxaban group and 96.6% of the warfarin group achieving complete dissolution (difference of -0.8% ; 95% CI: -5.7% to 4.1%; OR 0.98; 95% CI 0.74-1.29; p=0.88). Secondary endpoints, including mortality, stroke, and bleeding events, were similar in both groups.
Dr. Shah commented, “These findings support the use of rivaroxaban as a viable alternative to warfarin for treating left ventricular thrombus in post-MI patients. Rivaroxaban’s predictable dosing eliminates the need for regular blood tests, offering a more convenient and safer option for patients.”
Despite the positive results, the study had limitations. The open-label design may have introduced bias, as both patients and clinicians were aware of the treatment. Furthermore, the study was conducted at a single center in Karachi, Pakistan, limiting its generalizability. Due to limited funding, long-term follow-up was not possible, preventing assessment of recurrence rates after treatment discontinuation.