Highlight
• In the ATIS‑NVAF randomized trial (NCT03062319), adding an antiplatelet agent to anticoagulation after ischemic stroke or TIA in patients with nonvalvular atrial fibrillation (AF) and atherosclerotic cardiovascular disease produced no reduction in the composite of ischemic events and major bleeding at 2 years.
• The combination strategy did not significantly lower ischemic cardiovascular events (11.1% vs 14.2%; HR 0.76, 95% CI 0.39–1.48), but substantially increased major and clinically relevant nonmajor bleeding (19.5% vs 8.6%; HR 2.42, 95% CI 1.23–4.76).
Background: clinical context and unmet need
<pPatients with ischemic stroke or transient ischemic attack (TIA) who have comorbid nonvalvular atrial fibrillation face dual and competing vascular risks. AF is a potent risk factor for cardioembolic stroke and is managed principally with oral anticoagulation to reduce systemic embolism and recurrent stroke. Concurrent atherosclerotic cardiovascular disease (including extracranial/intracranial stenosis, ischemic heart disease, or peripheral artery disease) imparts additional risk from platelet-mediated arterial thrombosis.
In practice, clinicians sometimes add an antiplatelet agent to anticoagulation for perceived incremental prevention of atherothrombotic events. However, combining anticoagulants and antiplatelets raises bleeding risk, particularly intracranial and gastrointestinal hemorrhage, and there is limited randomized evidence to guide this tradeoff for patients whose index event is stroke/TIA rather than percutaneous coronary intervention (PCI) or acute coronary syndrome (ACS).
Study design
The ATIS‑NVAF trial is a multicenter, open‑label, randomized clinical trial conducted at 41 sites across Japan between November 2016 and March 2025. Eligible participants were adults with ischemic stroke or TIA within 8 to 360 days of onset, documented nonvalvular AF, and at least one manifestation of atherosclerotic cardiovascular disease (carotid or intracranial artery stenosis, prior noncardioembolic stroke, ischemic heart disease, or peripheral artery disease).
Participants were randomized to either combination therapy (an anticoagulant plus a single antiplatelet agent) or anticoagulant monotherapy. The primary outcome was a composite of ischemic cardiovascular events and major bleeding over 2 years. Secondary outcomes included ischemic cardiovascular events alone; safety outcomes included major bleeding and clinically relevant nonmajor bleeding.
The trial planned enrollment larger than the eventual sample but was stopped early for futility after an interim analysis; 316 patients were randomized (combination n = 159; monotherapy n = 157). The mean age was 77.2 years (SD 7.4) and 28.5% were female. Data were analyzed between April and October 2024; final follow‑up and reporting extend into 2025.
Key findings
The cumulative incidence of the primary composite outcome at 2 years was 17.8% in the combination therapy group and 19.6% in the anticoagulant monotherapy group (hazard ratio [HR] 0.91; 95% confidence interval [CI] 0.53–1.55; P = .64), indicating no statistically significant net clinical benefit from adding an antiplatelet.
When components were examined separately, ischemic cardiovascular events occurred in 11.1% of combination-treated patients versus 14.2% with monotherapy (HR 0.76; 95% CI 0.39–1.48; P = .41). These point estimates numerically favored combination therapy but were imprecise and did not reach statistical significance.
Bleeding was the dominant driver of harm. Major and clinically relevant nonmajor bleeding occurred in 19.5% of patients assigned to combination therapy compared with 8.6% on monotherapy (HR 2.42; 95% CI 1.23–4.76; P = .008). Thus, adding an antiplatelet approximately doubled bleeding risk in this population.
Put another way, the combination approach produced a small, non‑significant reduction in ischemic events while causing a substantial, statistically significant increase in bleeding — yielding no net benefit on the primary composite endpoint.
Safety details and subgroup considerations
The excess bleeding in the combination arm included both major bleeds and clinically relevant nonmajor bleeds, which are particularly consequential in an older population (mean age >77) where even nonmajor hemorrhage can prompt hospitalization, transfusion, or discontinuation of effective therapy. The trial report did not demonstrate a clear subgroup in which ischemic benefit clearly outweighed bleeding risk, although power for meaningful subgroup analyses was limited.
Expert commentary and comparison with prior evidence
ATIS‑NVAF fills an important evidence gap by directly testing routine addition of an antiplatelet to anticoagulation in patients whose index event was stroke/TIA and who also have atherosclerotic disease. Its principal finding — no net clinical benefit and markedly increased bleeding — aligns with the broader AF literature showing heightened hemorrhagic risk when antiplatelets are added to anticoagulation without compelling indication.
Evidence from PCI and ACS populations has repeatedly demonstrated that minimizing the duration of dual or triple therapy reduces bleeding without substantially increasing ischemic events when managed carefully. Trials such as WOEST (Lancet 2013), PIONEER AF‑PCI (NEJM 2016), RE‑DUAL PCI (NEJM 2017), and AUGUSTUS (NEJM 2019) showed that shorter or simplified regimens (e.g., anticoagulant plus single P2Y12 inhibitor) reduce bleeding and support tailored dual therapy after PCI rather than prolonged triple therapy. However, those studies address a different patient population (post‑PCI/ACS) and cannot be directly extrapolated to stable cerebrovascular disease after stroke/TIA.
The COMPASS trial (NEJM 2017) evaluating low‑dose rivaroxaban plus aspirin in stable atherosclerotic disease (without AF) showed fewer major cardiovascular events but more major bleeding compared with aspirin alone, illustrating the same tradeoff between ischemic benefit and bleeding. The ATIS‑NVAF results suggest that in patients with AF — where standard anticoagulation already addresses cardioembolism — routine addition of antiplatelet therapy to target atherosclerotic events does not clearly improve net outcomes and meaningfully increases harm.
Strengths and limitations
Strengths of ATIS‑NVAF include randomized design, multicenter conduct, pragmatic inclusion of patients with a common and clinically important comorbidity cluster (stroke/TIA + AF + atherosclerosis), and clinically meaningful endpoints combining ischemia and bleeding to reflect net clinical benefit.
Limitations are notable and temper interpretation. The trial was open‑label, which may influence management and reporting of some outcomes, though major bleeding and ischemic events are generally objective. Early termination for futility reduced statistical power and increased uncertainty around point estimates for ischemic outcomes. The sample size (n=316) was modest, and the population was older and geographically confined to Japan, which may limit generalizability to younger or ethnically different cohorts. Details on the specific antiplatelet agents used and anticoagulant types/dosing were not emphasized in the summary report; heterogeneity in agents may moderate effects. Finally, follow‑up was limited to 2 years — longer-term effects (both ischemic and bleeding) remain uncertain.
Clinical implications and practical recommendations
For clinicians managing patients with ischemic stroke/TIA, nonvalvular AF, and concurrent atherosclerotic disease, ATIS‑NVAF provides randomized evidence that routine addition of an antiplatelet agent to anticoagulation offers no net clinical benefit and substantially increases bleeding risk. In most such patients, anticoagulant monotherapy appears preferable unless there is a separate, compelling indication for antiplatelet therapy — most commonly recent ACS or recent PCI/stent placement, where short‑term combined therapy may be indicated following contemporary protocols and careful bleeding risk mitigation.
Decision making should remain individualized, balancing ischemic risk (CHA2DS2‑VASc, burden of atherosclerotic disease, recent coronary interventions) against bleeding risk (HAS‑BLED, age, prior hemorrhage, concomitant medications). When an antiplatelet is required, clinicians should employ the shortest effective duration, choose agents with more favorable bleeding profiles when possible, optimize blood pressure control and gastroprotection, and reassess need at regular intervals.
Research gaps and future directions
Key unanswered questions include whether specific subgroups (for example, patients with high‑risk intracranial atherosclerotic stenosis, multiple prior atherothrombotic events, or extensive coronary artery disease) derive clear ischemic benefit that offsets bleeding; whether particular antiplatelet agents or dosing strategies might modulate the risk–benefit ratio; and how differences between vitamin K antagonists and direct oral anticoagulants (DOACs) affect combined therapy outcomes. Larger, adequately powered randomized trials and pooled patient‑level meta‑analyses could clarify these issues, as could pragmatic trials stratified by plaque burden and by DOAC versus VKA use.
Conclusion
The ATIS‑NVAF randomized trial found that in patients with ischemic stroke or TIA, nonvalvular AF, and atherosclerotic cardiovascular disease, adding a single antiplatelet agent to anticoagulant therapy did not improve the composite of ischemic events and major bleeding over 2 years and markedly increased bleeding. These findings support anticoagulant monotherapy as the default strategy in this population absent other strong indications for antiplatelet therapy, and emphasize individualized risk assessment and short‑term, targeted use of combined regimens when necessary.
Funding and trial registration
Trial registration: ClinicalTrials.gov Identifier: NCT03062319. Funding sources were reported in the original publication (Okazaki et al., JAMA Neurology 2025); readers should consult the full text for sponsor details and disclosures.
References
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