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Abdul Mannan: A New DVT on Warfarin Is Not an INR Problem First

Abdul Mannan/LinkedIn

Jun 10, 2026, 13:19

Abdul Mannan: A New DVT on Warfarin Is Not an INR Problem First

Abdul Mannan, Consultant Haematologist at Betsi Cadwaladr University Health Board, shared a post on LinkedIn:

“A new DVT on warfarin is not an INR problem first.

It is an acute clot problem.

This comes up in APS, especially around pregnancy and the postpartum period.

A patient has DVT in pregnancy, receives LMWH, switches to warfarin after delivery, then develops another DVT.

The tempting answer is:

‘Just increase the INR target.’

But pause.

Here is the safer way to think:

Confirm it is a new clot, not old residual thrombus

Treat the acute event with therapeutic LMWH or UFH
Audit the warfarin: INR trend, TTR, adherence, drug interactions, diet, and INR reliability
If INR control was poor, this is not true warfarin failure
If recurrence happened despite good TTR at INR 2.0-3.0, then consider INR 3.0-4.0 or selected antiplatelet strategy

BSH 2024 is very helpful here.

It tells us to check INR reliability and time in therapeutic range before escalation. EULAR also supports INR escalation, aspirin addition, or LMWH in selected recurrent cases.

My teaching line for trainees:

Treat the clot with heparin. Then judge the warfarin.

One INR is a snapshot.

TTR is the story.

How do you approach recurrent thrombosis in APS in your centre?”

Abdul Mannan: A New DVT on Warfarin Is Not an INR Problem First