Key result
Untreated NVAF carries ~6-fold higher 1-year stroke risk with CHADS2 3–6 versus 0–1.
Why the study?
The incidence of stroke, systemic embolic events, and bleeding events in untreated NVAF patients after widespread DOAC use remained to be examined.
What is the incidence of stroke, systemic embolic events, and bleeding events across CHADS2 score strata in Japanese patients with non-valvular atrial fibrillation who do not receive anticoagulation therapy?
Cohort (n=7,001)
Yes
What is the incidence of stroke, systemic embolic events, and bleeding events across CHADS2 score strata in Japanese patients with non-valvular atrial fibrillation who do not receive anticoagulation therapy?
In contemporary Japanese clinical practice, over one-third of NVAF patients remain untreated with oral anticoagulants despite high 1-year stroke/SSE rates in those with CHADS2 scores ≥2 (3.2% to 8.0%), reinforcing guideline recommendations for anticoagulation in higher-risk patients.
Answers are grounded in this paper and cite their sources.
Substantial embolic risk in untreated CHADS2 ≥2 patients supports risk stratification; leaves open anticoagulation effects in this Japanese cohort.
OBJECTIVES: To examine the incidence of stroke or systemic embolic events (SSEs) and bleeding events in untreated patients with non-valvular atrial fibrillation (NVAF) after widespread use of direct oral anticoagulant agents (DOACs). DESIGN: Multicentre, non-interventional, observational, retrospective cohort study using real-world data in Japan (2016-2018). SETTING: The Mie, Musashino University study of NVAF, which used the Mie-Life Innovation Promotion Center Database. This is a regional clinical database involving one university hospital and eight general hospitals in Mie Prefecture in Japan. PARTICIPANTS: Japanese patients with NVAF (n=7001). PRIMARY AND SECONDARY OUTCOME: The incidence of SSEs and bleeding events. RESULTS: A total of 7001 patients with NAVF were registered, and 53.0% were treated with DOACs, 10.6% were treated with warfarin and 36.4% had no treatment. Additionally, 29.5% of patients with a CHADS2 (congestive heart failure, hypertension, age≥75 years, diabetes, previous stroke or transient ischemic attack) score of 3-6 were untreated. In the no treatment group, the SSE rates by the CHADS2 score (0, 1, 2 and 3-6) were 1.4%, 1.4%, 3.2% and 8.0%, respectively. The rates of bleeding events by the CHADS2 score (0, 1, 2 and 3-6) in the no treatment group were 0.7%, 1.0%, 1.2% and 2.9%, respectively. A multivariate analysis of SSEs in components of the CHADS2 showed that the adjusted HRs were 2.32 for heart failure, 1.66 for an age ≥75 years, 1.81 for diabetes mellitus and 5.84 for prior stroke or transient ischaemic attack. CONCLUSIONS: Approximately one-third of the patients do not receive any anticoagulation in the modern DOAC era in Japan. The SSE rate increases by the CHADS2 score. The SSE rate is low in patients with a CHADS2 score <1, supporting no indication of anticoagulation in current guidelines. In patients with a CHADS2 score >1, the use of anticoagulant drug therapy is recommended because of a higher risk of stroke.
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Tanizawa et al. (2022) conducted a cohort in Non-valvular atrial fibrillation (NVAF) (n=7,001). No oral anticoagulation therapy stratified by CHADS2 score vs. CHADS2 score strata (0, 1, 2, and 3-6) within the untreated NVAF subcohort was evaluated on 1-year incidence rate of stroke or systemic embolic events (SSEs) in untreated patients across CHADS2 scores (95% CI 6.1 to 10.5). Untreated non-valvular atrial fibrillation patients had 1-year stroke or systemic embolism rates increasing from 1.4% (CHADS2 0-1) to 3.2% (CHADS2 2) and 8.0% (CHADS2 3-6).
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