Heparin Bolus in Myocardial Infarction Management

Heparin Bolus Dosing by Reperfusion Strategy

The European Society of Cardiology recommends an initial IV bolus of 70-100 U/kg (maximum 5,000 U) when used alone for primary PCI 1
The European Society of Cardiology recommends a reduced dose of 60 U/kg (maximum 4,000 U) when used with glycoprotein IIb/IIIa inhibitors for primary PCI 1
The target activated clotting time (ACT) is 250-350 seconds (200-250 seconds with GPIIb/IIIa inhibitors) for primary PCI 1
Heparin infusion is typically discontinued at the end of the procedure for primary PCI 2
For patients receiving fibrinolytic therapy, an IV bolus of 60 U/kg (maximum 4,000 U) followed by an infusion of 12 U/kg/hour (maximum 1,000 U/hour) for 24-48 hours is recommended 2
The American College of Cardiology recommends targeting an aPTT of 50-70 seconds, with monitoring at 3, 6, 12, and 24 hours after initiation for fibrinolytic therapy 3, 2
Tissue plasminogen activators (t-PA) like alteplase require careful consideration of heparin dosing to minimize bleeding risk 4, 5

Heparin bolus followed by infusion improves coronary patency when used with tissue plasminogen activator, reducing the risk of reinfarction 3, 5
Heparin is particularly beneficial in specific high-risk subgroups, such as those with anterior wall MI or those likely to undergo early PCI 3
The American College of Cardiology recommends heparin for patients with unstable angina, as it significantly reduces the incidence of MI and refractory angina 6

The American College of Chest Physicians recommends maintaining an aPTT of 1.5-2.0 times control (50-70 seconds) for optimal efficacy and safety 3, 4
More frequent monitoring of aPTT and full weight adjustment of heparin may decrease the risk of non-cerebral bleeding complications 3
Continuation of heparin beyond 48 hours should be restricted to patients at high risk for systemic or venous thromboembolism 4

Low-molecular-weight heparins (LMWH) like enoxaparin have been studied as alternatives to UFH, with potential advantages in pharmacokinetics and reduced monitoring requirements 3, 1
For patients already on oral anticoagulants, the heparin bolus dose should be reduced, and INR should be checked prior to administration 8
Weight-based dosing protocols improve outcomes compared to fixed-dose regimens 7
A 5-day course of heparin appears to be as effective as a 10-day course for treatment 5, 6