This American Heart Association scientific statement reviews antithrombotic undertreatment: omission of an indicated drug, non-adherence, underdosing, and situations such as interactions or interruptions that leave levels subtherapeutic. It covers atrial fibrillation, venous thromboembolism and peripheral artery disease.
The authors set out how undertreatment is linked to more ischaemic stroke, systemic embolism, recurrent thrombosis and death, and how often it happens in real-world data. They trace it to deviations from evidence, to an overestimate of bleeding risk relative to clotting risk, and to inequities in access, which make the gaps worse in disadvantaged groups. Their answer is antithrombotic stewardship: structured, multidisciplinary review of who is on what, at what dose, and why.
For a cardiologist the practical step is simple and rarely done systematically: audit the anticoagulated patients you already have. Off-label dose reduction, a missing anticoagulant in a high-CHA₂DS₂-VASc patient deemed 'too frail', and an unplanned stop after a minor bleed are all things a clinic review can find. A statement is not a trial, but the underlying evidence on underdosing is consistent.
- Check every DOAC dose against its licensed reduction criteria at each review, not only at initiation.
- Ask about missed doses directly; non-adherence counts as undertreatment and is often invisible.
- Reassess patients whose anticoagulant was stopped after a bleed; many have a stronger case to restart than to stay off.
- Weigh stroke risk explicitly against bleeding risk when a patient seems 'too frail'; fear of bleeding is often overestimated.
- Consider a pharmacist-led or nurse-led anticoagulation review in clinic as a form of stewardship.
Why it matters
Underdosing feels cautious but trades a visible bleeding risk for an invisible stroke risk.
Don't overread it
This is an expert statement drawing on existing evidence, not a new trial.
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