Timing of Heparin Initiation in Atrial Fibrillation Patients with Stroke

Initial Management Approach

The American College of Chest Physicians recommends that heparin should not be started very early (<48 hours after stroke onset) in patients with atrial fibrillation who have suffered an acute ischemic stroke, due to increased risk of hemorrhagic transformation without clear benefit 1, 2
Very early anticoagulation (within 48 hours) using heparinoids or vitamin K antagonists should be avoided in patients with AF who have had an acute ischemic stroke, as it may increase the risk of symptomatic intracranial hemorrhage without net benefit 1
Heparinoids should not be used as bridging therapy in the acute phase of ischemic stroke, as they appear to increase the risk of symptomatic intracranial hemorrhage without net benefit 1

For patients with AF and acute ischemic stroke, oral anticoagulation should usually be started within 2 weeks of the stroke event, according to the American College of Chest Physicians 1
For patients at high risk of hemorrhagic conversion, the American Heart Association/American Stroke Association suggests that it is reasonable to delay initiation of oral anticoagulation beyond 14 days 3
For patients at low risk of hemorrhagic conversion, it may be reasonable to initiate anticoagulation between 2-14 days after the index event, as recommended by the American Heart Association/American Stroke Association 3

Infarct size is an important consideration, as larger infarcts have higher risk of hemorrhagic transformation and may require longer delays before anticoagulation, according to the American College of Chest Physicians 1
Normal baseline CT findings and age younger than 70 years have been associated with better neurological recovery with early heparin treatment, as reported in the Circulation journal 4, 5

When heparin is administered, close monitoring of aPTT is necessary to lessen the risk of hemorrhagic complications, as recommended by the American Heart Association 4, 6
Target aPTT should be 1.5 to 2.0 times control values, according to the Circulation journal 4, 6

Long-term oral anticoagulation is strongly indicated as secondary prevention in AF patients with stroke, according to the American College of Chest Physicians and the American Heart Association/American Stroke Association 1, 3
Direct oral anticoagulants (DOACs) are preferred over warfarin for patients without moderate to severe mitral stenosis or mechanical heart valves, as recommended by the American Heart Association/American Stroke Association 3

Initiating parenteral anticoagulation within 48 hours of stroke onset increases the risk of hemorrhagic transformation, as warned by the American College of Chest Physicians and the American Heart Association/American Stroke Association 1, 2
Delaying anticoagulation unnecessarily in patients at low risk for hemorrhagic transformation leaves them vulnerable to recurrent stroke, according to the American Heart Association/American Stroke Association 3
Inadequate monitoring of aPTT when heparin is administered can lead to either insufficient anticoagulation (increasing stroke risk) or excessive anticoagulation (increasing bleeding risk), as reported in the Circulation journal and the Arteriosclerosis, Thrombosis, and Vascular Biology journal 4, 6