ACLS review: Acute Coronary Syndromes Part 7

Unfractionated Heparin

·         Prevents thrombus formation over ruptured plaque surface

·         Prevents recurrence of thrombosis

·         Maintains patency of infarct-related artery

·         Prevent mural thrombus formation in patients with large infarctions

Unfractionated Heparin Disadvantages

·         Need for IV administration

·         Frequent monitoring of aPTT

·         Unpredictable anticoagulant response patients

·         May stimulate platelet activation, causing thrombocytopenia.

Unfractionated Heparin dosage

·         Initial bolus 60u/kg IV (maximum bolus: 4000 units)

·         Maintenance 12u/kg/hr

·         Keep PTT 1.5-2.0 times higher than control

·         Check PTT 3 hours after bolus then every 6 hours until stable then daily

·         Follow institutional heparin protocol

Unfractionated Heparin precautions

·         Active bleeding

·         Recent intracranial, intraspinal , eye surgery

·         Severe hypertension

·         Bleeding disorders

·         GI bleeding

Low-Molecular-Weight Heparin UA/NSTEMI

·         Enoxaparin:   similar or improved composite outcomes when enoxaparin was administered instead of UFH with non-ST-segment elevation ACS

·         Fondaparinux:  similar or improved outcomes without increased bleeding risks when fondaparinux was administered in-hospital rather than UFH in patients with non-ST-segment elevation ACS.

·         Bivalirudin:  No difference in outcome when compared to UFH in patients with non-ST-segment elevation ACS

Note:  Improved composite outcomes as evidenced by death, MI, and/or recurrent angina or recurrent ischemia or revascularization

Enoxaparin:  had an increase in the proportion of patients with minor bleeding complications

Fondaparinux:  was associated with increased risk of catheter thrombosis in PCI

Bivalirudin:  less bleeding risk was observed and no renal dosing is required.

Circulation. 2010; 122: S787-S817 doi: 10.1161/​CIRCULATIONAHA.110.971028

Low-Molecular-Weight Heparin STEMI

·         Enoxaparin:   improved outcomes when given instead of UFH to patients with STEMI undergoing fibrinolysis.

·         Fondaparinux:  superiority in clinical outcomes when compared to UFH in patients treated with fibrinolysis.

·         Insufficient evidence to recommend bivalirudin, nadroparin, reviparin, or parnaparin for use in STEMI patients undergoing fibrinolysis.

Note:  It is reasonable to administer enoxaparin in both the prehospital and hospital setting for a patient undergoing fibrinolysis

Fondaparinux may be considered in the hospital for patients treated specifically with non-fibrin-specific thrombolytics

Circulation. 2010; 122: S787-S817 doi: 10.1161/CIRCULATIONAHA.110.971028