Efficacy of Rivaroxaban Versus Warfarin in Patients with Acute Left Ventricular Thrombus Following Myocardial Infarction: An Open-Label Randomized Controlled Trial RIVAWAR Trial
Speaker: Dr. Jehangir Ali Shah
Key Highlights
Introduction:
Left ventricular thrombus (LVT) is a well-known complication following myocardial infarction (MI), leading to an increased risk of embolic events. The use of anticoagulants, such as warfarin, has been the traditional approach for LVT resolution. However, direct oral anticoagulants (DOACs) like rivaroxaban are emerging as potential alternatives due to their predictable dosing and lower monitoring requirements.
Objective:
To evaluate the efficacy and safety of rivaroxaban compared to warfarin in resolving post-MI LVT and reducing thromboembolic complications.
Methods:
This was a randomized controlled trial including patients diagnosed with LVT post-MI. Patients were randomized to receive either rivaroxaban or warfarin. The primary outcome was thrombus resolution at 4 and 12 weeks, assessed via echocardiography. Secondary outcomes included major bleeding, ischemic stroke, and all-cause mortality.
Baseline Characteristics:
|
Characteristics |
Value |
|
Patients |
80% Male |
|
Mean Age |
54.5 years |
|
ST-Elevation AMI |
90% |
|
Underwent Angioplasty |
85% |
|
Reduced Ejection Fraction (<35%) |
94% |
|
Time to Randomization (<48 hours) |
94% |
Results:
|
Outcome |
Rivaroxaban |
Warfarin |
p-value |
|
LV Thrombus Resolution (4 weeks) |
20% |
8.3% |
0.017 |
|
LV Thrombus Resolution (12 weeks) |
>95% |
>95% |
Non-significant |
|
All-Cause Mortality |
3.5% |
3.3% |
Non-significant |
|
Ischemic Stroke |
3.5% |
1.1% |
Non-significant |
|
Major Bleeding |
2.3% |
1.1% |
Non-significant |
Conclusion:
Rivaroxaban demonstrated similar efficacy to warfarin in resolving LVT at three months, with complete thrombus resolution in over 95% of patients in both groups. There was no significant difference in mortality, ischemic stroke, or major bleeding events. These findings support Rivaroxaban as a viable, non-inferior alternative to warfarin, offering predictable dosing without the need for routine INR monitoring in post-AMI LVT patients.
Stratified Randomization Study to Compare Different Duration of Dual Antiplatelet Therapy After Coronary Stenting in Either High or Low Bleeding Risk Population
Speaker: Dr. Hyo-Soo Kim
Key Highlights
Bleeding Risk and Prognostic Significance:
Bleeding risk is a crucial prognostic factor after PCI, similar to thrombotic risk. The Academic Research Consortium (ARC) proposed the High Bleeding Risk (HBR) definition. HBR is defined by an annual major bleeding risk of ≥4%. Major criteria and at least two minor criteria, including age and NSAID use, help stratify patients.
Guidelines and Stratification:
-
Guidelines strongly recommend stratifying patients based on ARC-HBR definition.
-
No prior study has evaluated specific DAPT duration based on ARC-HBR criteria.
General recommendation:
-
1-3 months DAPT for high bleeding risk (HBR) patients.
-
3-12 months DAPT for non-HBR patients.
-
However, no evidence supports the optimal DAPT duration under ARC-HBR criteria.
HOST-BR RCT Study Overview
-
First randomized study to stratify patients based on ARC-HBR criteria.
-
Evaluates different DAPT durations in high and low bleeding risk populations.
-
High bleeding risk stratum: Randomized to 1 vs. 3 months DAPT.
-
Low bleeding risk stratum: Randomized to 3 vs. 12 months DAPT.
-
Primary Endpoints and Hypothesis: Three co-primary endpoints assessed hierarchically:
-
Net Adverse Clinical Events (NACE)
-
Major Adverse Cardiac Events (MACE)
-
BARC Type 2-5 Bleeding at one year
-
Hypothesis: Shorter DAPT is non-inferior to longer DAPT for NACE and MACE, and superior for bleeding outcomes.
Study Design and Patient Enrolment:
-
1,600 patients required for high bleeding risk stratum.
-
Assumed NACE at one year: ~7-9%.
-
Non-inferiority margin: Risk difference of 2.7% (HR 1.3).
-
3,300 patients required for low bleeding risk stratum.
-
Assumed NACE at one year: ~4-5%.
-
Non-inferiority margin: Absolute risk difference of 1.5% (HR 1.3).
Study Organization and Flow
-
Nearly 5,000 patients enrolled and stratified based on ARC-HBR criteria.
-
Randomized into:
-
High bleeding risk: 1 vs. 3 months DAPT.
-
Low bleeding risk: 3 vs. 12 months DAPT.
-
Follow-up completed in over 99% of patients at one year.
Baseline Characteristics:
|
Characteristic |
High BR Stratum |
Low BR Stratum |
|
Age |
73 years |
63 years |
|
Female (%) |
1/3rd |
20% |
|
Stable CAD (%) |
40% |
40% |
|
ACS (%) |
60% (STEMI:5%) |
60% (STEMI:10%) |
|
Diabetes Mellitus (%) |
Over 50% |
1/3rd |
|
Chronic Kidney Disease (%) |
31.4% |
Rare |
|
Previous PCI (%) |
~20% |
- |
|
Clopidogrel-based DAPT Use (%) |
90% |
75% |
|
Anticoagulant Use (%) |
17% |
- |
Results:
Primary Endpoints:
|
Outcome |
High BR Stratum (One vs. Three Months) |
Low BR Stratum (One vs. Three Months)
|
|
One-year NACE |
18.4% (1M) vs. 14% (3M) Absolute risk difference: 4.4% Non-inferiority was not met |
2.9% (3M) vs. 4.4% (12M) Non-inferiority was met |
|
One-year MACE |
9.8% (1M) vs. 5.8% (3M) Absolute risk difference: 4% |
2.2% (3M) vs. 2.3% (12M) Non-inferiority was met |
|
Any actionable bleeding |
13.8% (1M) vs. 15.8% (3M) |
7.4% (3M) vs. 11.7% (12M) |
Clinical Outcomes:
-
High BR Stratum (One vs. Three-Month DAPT): One-month DAPT associated with:
-
Higher incidence of cardiac death, ischemic stroke, and target lesion revascularization
-
Lower incidence of minor bleeding but not major bleeding
-
Low BR Stratum (Three vs. Twelve-Month DAPT): Three-month DAPT associated with:
-
Lower incidence of hemorrhagic stroke
-
Lower incidence of minor (BARC2) and major bleeding (BARC3)
Conclusion:
These findings suggest that a shorter DAPT duration may be a safer option in low BR patients, while high BR patients may require a more cautious approach to balance ischemic and bleeding risks.
ACC.25, March 29 - 31, 2025, Chicago
