What is the clinical evidence from this study?

Study design: Cohort. Population: Myocardial infarction (n=85360). Intervention: Oral anticoagulation (OAC) vs. No OAC. Primary outcome: Ischemic stroke (aHR 0.56, 95% CI 0.41-0.77).

What does this research mean for the field?

Oral anticoagulation reduces ischemic stroke risk in myocardial infarction survivors with atrial fibrillation, but provides no significant stroke-preventive benefit in those without atrial fibrillation. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

This study aims to determine how oral anticoagulation affects stroke risk after myocardial infarction, particularly in relation to atrial fibrillation history.

May 8, 2026Open Access

Abstract Number: Esoc2026a508 Effect of Oral Anticoagulation on Stroke Risk After Myocardial Infarction Differs by the Presence of Atrial Fibrillation

Key Result

Oral anticoagulation was associated with reduced ischemic stroke risk in MI survivors with atrial fibrillation (aHR 0.56; 95% CI 0.41-0.77), but showed no significant benefit in those without AF.

Key Points

This study aims to determine how oral anticoagulation affects stroke risk after myocardial infarction, particularly in relation to atrial fibrillation history.
Participants were myocardial infarction survivors from the SWEDEHEART registry, following a 6–10 week post-discharge follow-up.
Fine–Gray competing-risk regression evaluated the relationships between atrial fibrillation, oral anticoagulation, and stroke, including interaction effects.
Among 85,360 MI survivors, 4,275 (5.0%) experienced stroke; AF increased ischemic stroke risk (aHR 1.40, 95% CI 1.19–1.64).
Oral anticoagulation use showed no significant benefit in MI patients without AF (aHR 1.18, 95% CI 0.92–1.51).
A significant interaction (AF–OAC) revealed that OAC reduced ischemic stroke risk in AF patients (aHR 0.56, 95% CI 0.41–0.77).

Study Design

Type

Cohort (n=85,360)

Multicenter

Yes

Structured PICO

Does oral anticoagulation reduce stroke risk in MI survivors with and without atrial fibrillation?

Population

85,360 MI survivors from the national SWEDEHEART registry who attended a 6–10-week post-discharge follow-up between 2005 and 2020 (mean age 64 ± 9 years, 74.3% men).

Intervention

Oral anticoagulation (OAC)

Comparator

No oral anticoagulation

Outcome

Ischemic or hemorrhagic strokehard clinical

Oral anticoagulation reduces stroke risk in post-MI patients with atrial fibrillation, but provides no stroke-preventive benefit in those without atrial fibrillation.

Main Result

Effect estimate: aHR 0.56 (95% CI 0.41-0.77)

Abstract

Abstract Background and aims Stroke risk remains elevated after myocardial infarction (MI). Oral anticoagulation (OAC) is recommended in survivors with atrial fibrillation (AF) and is also used in some patients without AF, for other indications such as left ventricular thrombus. However, whether OAC reduces stroke risk independently or only among patients with AF remains uncertain. This study examined whether the association between OAC and stroke risk after MI differs by AF history. Methods MI survivors from the national SWEDEHEART registry (Swedish Web-system for Evidence-based Care in Heart Disease) who attended a 6–10-week post-discharge follow-up between 2005 and 2020 were included. Fine–Gray competing-risk regression assessed associations between AF, OAC, and stroke, including interaction testing between AF and OAC. Results Among 85,360 MI survivors (mean age 64 ± 9 years, 74.3% men), 7,285 (8.5%) received OAC; 4,978 (68.3%) had AF and 2,307 (31.7%) did not. During follow-up, 4,275 (5.0%) experienced ischemic or hemorrhagic stroke. AF increased ischemic stroke risk (aHR 1.40, 95% CI 1.19–1.64), while OAC use alone showed no significant benefit (aHR 1.18, 95% CI 0.92–1.51). A significant AF–OAC interaction showed reduced ischemic stroke risk in patients with AF (aHR 0.56, 95% CI 0.41–0.77), with a similar trend for hemorrhagic stroke. Conclusions OAC was associated with reduced stroke risk in MI patients with AF, but not in those without AF. These findings highlight the absence of a stroke-preventive effect in non-AF patients and underscore the need to better understand the rationale for extended OAC use in this group. Conflict of interest Putu Ayuwidia Ekaputri: nothing to disclose; Adam Viktorisson: nothing to disclose; Petra Redfors: nothing to disclose. Margrét Leósdóttir: nothing to disclose. Katharina Stibrant Sunnerhagen: nothing to disclose.