From the Guidelines
For NSTEMI due to demand ischemia, a heparin bolus is not recommended as standard treatment. Demand ischemia occurs when increased oxygen requirements exceed supply, rather than from acute plaque rupture or thrombosis. Management should focus on correcting the underlying cause of increased demand or decreased supply. According to the acc/aha 2007 guidelines 1, anticoagulant therapy should be managed based on the post-angiography management strategy, but there is no specific recommendation for a heparin bolus in cases of demand ischemia. The guidelines do recommend continuing intravenous UFH for at least 48 h or until discharge if given before diagnostic angiography for patients with UA/NSTEMI in whom medical therapy is selected as a post-angiography management strategy and in whom CAD was found on angiography 1. However, this does not necessarily apply to demand ischemia cases.
Some key points to consider in managing NSTEMI due to demand ischemia include:
- Correcting the underlying cause of increased demand or decreased supply
- Controlling heart rate, treating anemia, optimizing blood pressure, or managing respiratory status
- Individualizing treatment based on the patient's bleeding risk and overall clinical picture
- Balancing the potential benefits of preventing further thrombosis against the risks of bleeding complications in a patient who may not have an active thrombotic process, as noted in the guidelines 1.
In general, the focus should be on addressing the precipitating factors rather than automatically initiating anticoagulation with heparin. The decision to use anticoagulation should be made on a case-by-case basis, considering the patient's specific clinical scenario and risk factors, as suggested by the guidelines 1.
From the Research
Heparin Bolus for NSTEMI Due to Demand Ischemia
- The use of heparin in patients with non-ST-segment elevation myocardial infarction (NSTEMI) is a common practice, as seen in studies such as 2 and 3.
- According to 3, an initial heparin bolus of 60 to 70 U/kg (maximum, 5000 U) followed by a 12- to 15-U/kg/h infusion is recommended for patients with NSTEMI.
- However, the study 2 found that excess weight-adjusted UFH bolus or infusion dose was administered 35% of the time, and this was associated with an increased risk of major bleeding.
- Another study 4 found that heparins compared with placebo reduced the occurrence of myocardial infarction in patients with unstable angina and NSTEMI, but there was a trend towards more major bleeds in the heparin studies.
- The use of anticoagulation in NSTEMI is also discussed in 5, which suggests that patients presenting with NSTEMI should be initiated on anticoagulation for the initial hospitalization period.
- A more recent study 6 compared the outcomes of bivalirudin and heparin in patients with NSTEMI undergoing percutaneous coronary intervention (PCI) and found that bivalirudin reduced serious bleeding compared with heparin.
Key Findings
- Heparin is commonly used in patients with NSTEMI, but the optimal dosing strategy is still a topic of debate.
- Excess weight-adjusted heparin dosing is associated with an increased risk of major bleeding.
- Heparins reduce the occurrence of myocardial infarction in patients with unstable angina and NSTEMI, but may increase the risk of major bleeding.
- Anticoagulation is an important part of the treatment strategy for patients with NSTEMI, and the choice of anticoagulant and dosing strategy should be individualized based on patient characteristics and clinical presentation.