Is heparin (unfractionated heparin) indicated in acute ischemic stroke?

Heparin is NOT Indicated for Acute Ischemic Stroke Treatment

Unfractionated heparin (whether intravenous or subcutaneous) is not recommended for reducing morbidity, mortality, or early recurrent stroke in acute ischemic stroke because any potential benefit in reducing recurrent stroke is negated by a concomitant increase in hemorrhagic complications. 1

Primary Treatment Recommendation

• Aspirin (160-325 mg) should be initiated within 24-48 hours of acute ischemic stroke onset to reduce mortality and morbidity, provided the patient has not received or will not receive thrombolytic therapy 1, 2
• Aspirin is the preferred antiplatelet agent over any form of heparin for acute stroke management 1

Evidence Against Heparin Use

Dose-Adjusted Unfractionated Heparin

• Not recommended for reducing morbidity, mortality, or early recurrent stroke in the first 48 hours because evidence indicates it is not efficacious and may be associated with increased bleeding complications (Grade B recommendation) 1

Fixed-Dose Subcutaneous Heparin

• Not recommended for decreasing risk of death, stroke-related morbidity, or preventing early stroke recurrence (Grade A recommendation) 1
• Although some evidence shows it reduces early recurrent ischemic stroke, this benefit is completely offset by increased hemorrhage 1

Intravenous Heparin

• Not recommended for any specific stroke subgroup including cardioembolic, large vessel atherosclerotic, vertebrobasilar, or "progressing" stroke because data are insufficient (Grade U) 1
• Even in atrial fibrillation patients, low-molecular-weight heparin (dalteparin) is not more efficacious than aspirin, and aspirin is easier to administer 1

The Only Acceptable Use: DVT Prophylaxis

Subcutaneous unfractionated heparin, low-molecular-weight heparins, or heparinoids may be considered solely for DVT prophylaxis in at-risk, immobilized patients with acute ischemic stroke (Grade A recommendation) 1, 2

• This indication is for prophylactic dosing only, not therapeutic anticoagulation 1
• Non-pharmacologic treatments (intermittent pneumatic compression) are equally valid alternatives 2
• No benefit has been demonstrated for reducing pulmonary embolism 1
• The benefits must be weighed against risks of systemic and intracerebral hemorrhage 1

Why Heparin Fails in Acute Stroke

The fundamental problem is that any reduction in early recurrent stroke is counterbalanced by increased hemorrhagic complications, resulting in no net clinical benefit 1, 3, 4

• The International Stroke Trial showed heparin was associated with significant excess bleeding complications but no clinical benefit at 6 months 5
• A 2013 meta-analysis of individual patient data from five large randomized trials found no evidence that patients at higher risk of thrombotic events or lower risk of hemorrhagic events benefited from heparins 4
• Patients who might theoretically benefit most (advanced age, increased neurological impairment, atrial fibrillation) are paradoxically at high risk for both thrombotic and hemorrhagic events 4

Rare Exceptions (Case-by-Case Consideration Only)

While guidelines do not support routine use, some experts suggest heparin might be considered in highly select circumstances 6, 7:

• Non-occlusive intraluminal thrombus documented on imaging (case series showed potential benefit without hemorrhage) 7
• Symptomatic large artery stenosis >70% with evidence of progression 6
• Mechanical heart valves or left ventricular assist devices where thrombotic risk is extraordinarily high 6

However, even in these scenarios, there are no randomized controlled trials supporting this approach, and it remains controversial 6, 3

Critical Pitfalls to Avoid

• Never use heparin as a substitute for thrombolytic therapy in eligible patients 2, 8
• Never administer heparin within 24 hours of thrombolytic therapy due to dramatically increased bleeding risk 2, 8
• Do not assume cardioembolic strokes benefit from acute heparin - the risk of early recurrent cardioembolic stroke is actually low, and aspirin is equally effective 1
• Avoid the misconception that "progressing stroke" requires heparin - no evidence supports this practice 1

Practical Algorithm

1. Acute ischemic stroke confirmed on imaging → Start aspirin 160-325 mg within 24-48 hours (unless thrombolysis given) 1, 2
2. Immobilized patient at risk for DVT → Consider prophylactic-dose subcutaneous heparin or pneumatic compression 1, 2
3. All other scenarios → Do not use therapeutic heparin; continue aspirin 1

The evidence is clear and consistent: therapeutic heparin has no role in routine acute ischemic stroke management 1, 4