Adding low-dose rivaroxaban to DAPT did not significantly reduce LV thrombus in anterior STEMI patients.

This randomized clinical trial investigated the efficacy of adding low-dose rivaroxaban to dual antiplatelet therapy (DAPT) for preventing left ventricular (LV) thrombus formation in patients with anterior ST-segment elevation myocardial infarction (STEMI). The study enrolled a total of 560 patients across 29 centers in France. The population consisted of patients presenting with anterior STEMI, a high-risk subset of myocardial infarction associated with significant left ventricular dysfunction and thrombus risk. The intervention arm received DAPT, defined as aspirin at a dose of 100 mg or less per day, combined with either clopidogrel at 75 mg per day or ticagrelor at 90 mg twice daily, plus rivaroxaban at a dose of 2.5 mg twice daily for a duration of four weeks. The comparator arm received DAPT alone without the addition of the direct oral anticoagulant. The primary outcome was the presence of LV thrombus assessed via contrast-enhanced cardiac magnetic resonance imaging at one month post-randomization. The study design was a randomized clinical trial, though the specific phase of development for the intervention is not reported in the provided data.

The primary outcome analysis revealed that 38 patients (13.7%) in the rivaroxaban group had an LV thrombus at one month, compared to 47 patients (16.6%) in the DAPT alone group. The absolute difference was -2.9%, with a 95% confidence interval ranging from -8.9% to 3.2% and a p-value of .34. This result indicates no statistically significant reduction in LV thrombus incidence with the addition of rivaroxaban. The direction of the effect was neutral, suggesting that the modest sample size may have been insufficient to detect a clinically meaningful difference if one existed.

Secondary outcomes included the largest diameter of LV thrombus, incidence of major adverse cardiovascular events, and bleeding events. Regarding bleeding safety, major bleeding events defined by the Bleeding Academic Research Consortium (BARC) type 2 or higher occurred in 4 patients (1.5%) of the rivaroxaban group versus 2 patients (0.7%) in the DAPT alone group. The difference was 0.7% (95% CI, -1.3% to 3.1%), indicating comparable rates of major bleeding between the two strategies. However, minor bleeding events (BARC type 1) were more frequent in the rivaroxaban group, occurring in 45 patients (16.4%) compared to 20 patients (7.2%) in the DAPT alone group, representing an absolute difference of 9.3% (95% CI, 3.6% to 14.8%). Serious adverse events, discontinuations, and specific tolerability profiles were not reported in the provided data.

When compared to prior landmark studies in the therapeutic area of post-MI anticoagulation, this trial adds to the growing body of evidence regarding the role of direct oral anticoagulants in preventing LV thrombus. Previous research has explored the balance between thrombus prevention and bleeding risk in this population. The results of this specific trial suggest that the bleeding risk associated with adding rivaroxaban to DAPT may not be justified by a clear reduction in thrombus formation in this specific cohort. The study limitations are explicitly noted as having limited power, which is consistent with the non-significant primary outcome and the wide confidence intervals observed. This lack of power prevents definitive conclusions about whether a modest protective effect exists but was undetected.

Clinical implications of these findings suggest that the routine addition of low-dose rivaroxaban to DAPT for four weeks in patients with anterior STEMI cannot be recommended based on this evidence alone. The increased rate of minor bleeding events without a statistically significant reduction in thrombus or major bleeding raises questions about the net clinical benefit. Practitioners must interpret these findings with caution, acknowledging that a modest effect cannot be excluded due to the study's design constraints. Further research with larger sample sizes may be necessary to clarify the role of low-dose rivaroxaban in this setting. Questions remain unanswered regarding long-term outcomes beyond the one-month follow-up period and the impact of varying degrees of left ventricular dysfunction on thrombus risk. Until more robust data are available, current guidelines regarding anticoagulation in post-MI patients should be weighed carefully against the potential for increased minor bleeding.