This retrospective study was conducted on 63 patients with left ventricle thrombus treated with rivaroxaban or warfarin. Time to resolution was shorter with rivaroxaban with no difference in the resolution rate and complications between groups.
The use of rivaroxaban in the management of left ventricle thrombus was reported in several conditions. Rivaroxaban was used to manage a patient with tachycardia-induced heart failure and failed warfarin therapy [8], and patients with poor anticoagulation quality, and the reported outcomes were good [9]. Left ventricle thrombus complicating myocardial infarction was treated with rivaroxaban combined with dual antiplatelet therapy, and thrombus resolution was reported in a variable time from 1 to 3 months [10]. Complete dissolution of thrombus within 2 to 4 weeks in patients with acute coronary syndrome after the percutaneous coronary intervention was reported [1]. The median duration of rivaroxaban treatment for the resolution of the left ventricle thrombus in a meta-analysis of 29 patients was 30 days [10]. We did not find a difference in the number of patients who had thrombus resolution in the rivaroxaban vs. warfarin group. However, the time to resolution was shorter in patients who had rivaroxaban.
Data on direct oral anticoagulants, specifically in patients with intra-cardiac thrombus, are limited [11]. In a randomized trial, rivaroxaban was more effective than warfarin in the resolution of left atrial thrombus in patients with non-valvular atrial fibrillation [12].
In a recent cohort study, warfarin (n= 300) was compared with DOAC (n= 185) to manage LV thrombus. The risk of ischemic stroke and systemic emboli was higher with DOAC [13]. The difference in the outcomes between this study and our research could be attributed to the different sample sizes that could not detect a difference in complication rate. Additionally, we included patients who had rivaroxaban only, and the response to various DOACs could differ.
The rate of thrombus resolution was evaluated in scarce studies. Jones and associates reported a higher LV thrombus resolution rate in patients who received DOAC than warfarin in a study of 101 patients who had LV thrombus after acute myocardial infarction in 3 years [14]. Moreover, they reported a higher rate of bleed with DOAC and no difference in thromboembolic complications [14]. On the other hand, Bass and colleagues reported higher blood transfusion requirements in patients who received warfarin than DOAC and no difference in other outcomes [15].
In a study on DOAC therapy in patients with left ventricle thrombus, gastrointestinal bleeding requiring transfusion with reported in 2/17 patients [16]. Our patients were screened for bleeding according to the BARC definition, and two patients had bleeding in the rivaroxaban group compared to one patient in the warfarin group. The initial reports on the use of rivaroxaban for the management of left ventricle thrombus are encouraging. It showed a high efficacy with few side effects. One of the potential advantages of rivaroxaban is that it does not need monitoring. Three patients were shifted to rivaroxaban, which was indicated due to poor INR control in those patients.
The efficacy of warfarin was assessed with time in the therapeutic range (TTR) in several studies [17]. Maniwa and colleagues found that appropriate anticoagulation treatment confirmed with TTR could reduce embolism risk without increasing bleeding risk [18]. We did not study this relation in our study as the sample size is too small to generate sufficient TTR to compare. In a study by Sumaya and associates, delayed thrombus lysis was associated with worse outcomes [19]. We did not find this relation in our study, which could be attributed to the small sample size. However, there is a potential advantage of rivaroxaban in those patients since it is associated with the faster resolution, which could decrease the adverse events if used on a wide scale.
Our study had several limitations, including the small patients’ number, which is accepted for this new off-label indication of rivaroxaban. The sample size was sufficient to detect a difference in time to thrombus resolution; however, the lack of significant difference in complication rates could be an issue. The study is a retrospective research with its inherent selection and referral biases. However, we reported faster resolution of LV thrombus with DOAC, which is under-reported in the literature. The study highlighted rivaroxaban’s safety in patients with LV thrombus, and further randomized trials are warranted.