What is the clinical evidence from this study?

Study design: Cohort. Population: Atrial fibrillation (n=388214). Intervention: Direct oral anticoagulants (DOACs) vs. Warfarin. Primary outcome: Ischemic stroke (in patients with prior gastrointestinal surgery) (aHR 0.35, 95% CI 0.17-0.72).

What does this research mean for the field?

In patients with atrial fibrillation, gastrointestinal surgery significantly increases the risk of ischemic stroke among warfarin users but not DOAC users, with DOACs demonstrating a substantially lower stroke risk than warfarin post-surgery. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

This research aims to explore the risks of ischemic stroke associated with anticoagulants in atrial fibrillation patients who have undergone gastrointestinal surgery.

April 25, 2026Open Access

Gastrointestinal Surgery Status and the Risks of Ischemic Stroke and Safety Outcomes With Direct Oral Anticoagulants Versus Warfarin in Atrial Fibrillation: A Nationwide Population-Based Cohort Study

Key Result

In patients with atrial fibrillation, gastrointestinal surgery significantly increased ischemic stroke risk among warfarin users but not DOAC users, with DOACs demonstrating a lower stroke risk than warfarin after surgery (aHR 0.35).

Key Points

This research aims to explore the risks of ischemic stroke associated with anticoagulants in atrial fibrillation patients who have undergone gastrointestinal surgery.
Population-based cohort study
Comparison of outcomes in atrial fibrillation patients using DOACs and warfarin after GI surgery
GI surgery increased ischemic stroke risk in warfarin users but not in DOAC users.
DOACs showed a favorable safety profile post-GI surgery compared to warfarin.
More favorable outcomes were observed for DOACs after upper GI surgery.

Study Design

Type

Cohort (n=388,214)

Multicenter

Yes

Structured PICO

Does direct oral anticoagulant use compared to warfarin reduce ischemic stroke and safety outcomes in atrial fibrillation patients who have undergone gastrointestinal surgery?

Population

388,214 adult (≥20 yr) patients with atrial fibrillation newly prescribed oral anticoagulants, mean age 71.9 years, 42.7% male, from a South Korean nationwide cohort. Key exclusions: valvular AF, history of pulmonary thromboembolism, deep vein thrombosis, or recent joint replacement surgery. Mean CHA₂DS₂-VASc score 3.5.

Intervention

Direct oral anticoagulants (apixaban, dabigatran, rivaroxaban, or edoxaban) evaluated with time-varying status of gastrointestinal surgery (gastrectomy, bariatric surgery, small bowel resection, or colectomy) during follow-up.

Comparator

Warfarin evaluated with time-varying status of gastrointestinal surgery during follow-up.

Outcome

Incident ischemic stroke, defined as a hospitalization with a primary diagnosis ICD code of I63 or I64, a minimum hospital stay of 3 days, and at least one documented brain imaging study.hard clinical

DOACs maintain a favorable efficacy and safety profile compared to warfarin in patients with atrial fibrillation who undergo gastrointestinal surgery, avoiding the increased ischemic stroke risk seen with warfarin post-surgery.

Main Result

Effect estimate: aHR 0.35 (95% CI 0.17-0.72)

Absolute Event Rate: 1.61% vs 4.84%

Limitations

Observational study design with potential residual confounding
Potential for extreme weights in IPTW due to the small size of the WFR/GIS+ group
Ischemic stroke etiology and causes of death were unavailable
Inclusion of only Asian patients may limit generalizability
Differences across specific DOAC types and detailed GI surgery types could not be fully evaluated

Abstract

In AF patients, GI surgery significantly increased ischemic stroke risk among warfarin users, but not among DOAC users. DOACs showed generally favorable profiles after GI surgery and may remain a reasonable anticoagulant, with potentially more favorable profile after upper GI surgery.

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