Timing of Heparin and Warfarin After Alteplase Thrombolysis

Heparin Initiation

The American College of Cardiology recommends heparin initiation when the aPTT has decreased to less than twice the normal control value after completing alteplase infusion, typically without a loading dose 1
Heparin infusion should begin when aPTT falls below 2× the upper limit of normal following alteplase completion, with a protocol using heparin at 1,280 IU/hour continuous infusion 2
In patients with prosthetic valve thrombosis, heparin treatment without a loading dose should begin when the aPTT has decreased to less than twice the normal control value 1

The target aPTT should be 1.5 to 2 times normal, with an average dosage to achieve therapeutic effect of 20,000 to 40,000 U/24 hours, and initial dosing typically around 1,300 U/hour 1
aPTT should be checked four times every 6 hours and three times every 8 hours during the first 24-48 hours after stopping thrombolysis, then daily, due to rapidly changing levels of fibrinogen and heparin-binding proteins 1

In pediatric patients, heparin should be continued during alteplase administration at 10 μg·kg⁻¹·h⁻¹, and increased to age-appropriate dose after alteplase completion 3, 4
For acute ischemic stroke patients, antithrombotic therapy, including heparin, should be avoided for the first 24 hours after IV alteplase unless there are compelling concomitant conditions 5

Warfarin may be started as soon as the diagnosis requiring anticoagulation is confirmed, even during thrombolytic therapy 2
A 5-day heparin course appears as effective as a 7-10 day course, and heparin should be continued until adequate maintenance anticoagulation with warfarin is achieved 2

The target INR should be 2.5 to 3.5 for most indications post-thrombolysis, with the addition of low-dose aspirin (81 to 100 mg daily) strongly recommended once warfarin is therapeutic 1, 6

Adjuvant anticoagulant therapy should not be administered during active thrombolytic infusion, except in specific pediatric protocols or certain endovascular procedures 1, 6
Heparin should not be started too early when aPTT is still >2× normal, and heparin loading dose should not be given immediately post-thrombolysis 1, 2
Platelet count should be monitored if heparin is continued beyond 5 days due to risk of heparin-induced thrombocytopenia with thrombosis 2
For stroke patients specifically, the 24-hour window without antithrombotics should be respected unless exceptional circumstances exist 5