AHA statement: underdosed and omitted anticoagulation is a preventable cause of stroke

Design

AHA scientific statement (evidence review)

Population

Patients with atrial fibrillation, venous thromboembolism or peripheral artery disease

Primary outcome

Harms of antithrombotic omission, underdosing and non-adherence

Effect

Undertreatment linked to more ischaemic stroke, systemic embolism, recurrent thrombosis and death

An American Heart Association scientific statement, published in Circulation on 1 October, addresses antithrombotic undertreatment: drugs not prescribed when indicated, doses below what the label supports, non-adherence, and situations that leave patients with subtherapeutic levels. It is a review of evidence and practice, not a new trial.

It identifies the drivers as departure from evidence-based practice, overestimation of bleeding relative to thrombotic risk, and unequal access to care. The consequences it describes are higher rates of ischaemic stroke, systemic embolism, recurrent venous thrombosis and death, in atrial fibrillation, venous thromboembolism and peripheral artery disease. Real-world data show the gaps are widest in socially disadvantaged patients. The proposed answer is structured, multidisciplinary antithrombotic stewardship.

The commonest version in clinic is the direct oral anticoagulant given at a reduced dose without meeting the label's dose-reduction criteria, often out of bleeding worry in an older patient. In India, cost and intermittent supply add non-adherence to the list. Dose-reduction criteria differ by drug, and they are worth checking against the label rather than memory.

• At each review of a patient on a direct oral anticoagulant, check that the dose matches the label's criteria for that drug: age, weight, creatinine clearance and interacting drugs.
• Do not reduce an anticoagulant dose for bleeding worry alone when the patient does not meet reduction criteria; address modifiable bleeding risks instead.
• Ask directly about missed doses and cost; stopping when a strip runs out is common.
• Recalculate creatinine clearance at least yearly, and sooner in older or unwell patients, since the right dose can change in both directions.
• In atrial fibrillation with a stroke-risk indication, record the reason if anticoagulation is not prescribed.

Why it matters

An anticoagulant at the wrong low dose gives the bleeding risk of treatment without its full stroke protection.

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