Treatment - STEMI Revascularization

Treatment – CAD - STEMI

The treatment of STEMI includes prompt revascularization and medical therapy. Revascularization can be performed by either primary PCI, fibrinolytic therapy (thrombolytic therapy) or surgically. Primary PCI is preferred if available within a reasonable timeframe — that is, a door-to-balloon time of less than 90 minutes.

Revascularization

The decision whether to undertake primary PCI or fibrinolytic therapy is important. Many major medical facilities have PCI capabilities, and this is the treatment of choice for STEMI. Smaller hospitals or those in rural areas may not have PCI capabilities; however, those facilities frequently have capabilities to quickly transfer patients experiencing STEMI to a primary PCI facility. When there is no primary PCI available and transfer to a primary PCI facility is not available in a timely fashion — that is, transfer in less than 60 minutes — fibrinolytic therapy is indicated.

Primary PCI

In most situations, primary PCI is strongly preferred over thrombolytic therapy; this includes primary PCI within 36 hours for patients who develop cardiogenic shock and those with Killip Class III HF. There are no situations in which fibrinolytic therapy is preferred over primary PCI, unless the patient refuses invasive procedures. Fibrinolytic therapy is most effective within 3 hours of symptom onset.

The best outcomes occur when primary PCI is performed with a door-to-balloon time of less than 90 minutes and when symptom onset was less than 12 hours before the intervention. With delayed presentation (symptom duration 12-24 hours), it is reasonable to perform a primary PCI if there is evidence of ongoing ischemia. [O’Gara 2013;13A(Table 2)] Primary PCI is not recommended when symptom onset is more than 12 hours before evaluation and the patient is asymptomatic; see Occluded Artery Trial (OAT).

Fibrinolytic Therapy

Fibrinolytic therapy must be instituted within 24 hours of symptom onset. After this time frame, fibrinolysis is contraindicated and likely to be ineffective. Note that fibrinolytic therapy is always given simultaneously with anticoagulation using unfractionated heparin or low molecular weight heparin (enoxaparin or fondaparinux).

If the preferred management for a patient with STEMI is fibrinolytic therapy because primary PCI is not available, contraindications must be considered. Suspected aortic dissection, active bleeding (excluding menses), or a bleeding diathesis are contraindications to fibrinolytic therapy. Generally, if there is high (> 4%) risk for intracranial hemorrhage (ICH), fibrinolytic therapy is also contraindicated.

According to the American College of Cardiology/American Heart Association guidelines, the following factors are considered absolute contraindications for fibrinolytic therapy in STEMI: [O’Gara 2013;19b(Table 6)]

1. Prior intracranial hemorrhage
2. Ischemic stroke within 3 months (EXCLUDING acute ischemic stroke within 4.5 hours)
3. Known cerebrovascular abnormality such as aneurysm or arteriovenous malformation
4. Known malignant intracranial tumor
5. Significant closed head trauma or facial trauma within 3 months
6. Intracranial or intraspinal surgery within 2 months
7. Suspected aortic dissection
8. Severe uncontrolled hypertension (unresponsive to emergency therapy)
9. Active bleeding or bleeding diathesis (excluding menses)
10. For streptokinase only, prior treatment within the previous 6 months

Relative (not absolute) contraindications to fibrinolytic therapy include:

1. Uncontrolled hypertension (BP > 180/110 mm Hg) either currently or in the past
2. Intracranial abnormality not listed as absolute contraindication (eg, benign intracranial tumor)
3. Ischemic stroke more than 3 months prior
4. Bleeding within 2 to 4 weeks (menses excluded)
5. Traumatic or prolonged cardiopulmonary resuscitation
6. Major surgery within 3 weeks
7. Pregnancy
8. Current use of anticoagulants
9. Noncompressible vascular puncture
10. Dementia

Advanced age is not listed as an absolute or relative contraindication to fibrinolytic therapy in the ACC/AHA guidelines.

“Facilitated PCI” refers to using initial fibrinolytic therapy to stabilize the patient while transport to a primary PCI facility is being arranged. This strategy failed to demonstrate a net clinical benefit in two large trials (ASSENT-4 PCI and FINESSE).

“Rescue PCI” refers to the use of PCI when fibrinolytic therapy fails. This is indicated after fibrinolytic therapy when cardiogenic shock or severe congestive HF develops (Killip Class III), or when electrical instability (ventricular tachycardia or fibrillation) or persistent ischemic symptoms are present.

Coronary Artery Bypass Grafting (CABG)

According to the ACC/AHA guidelines, urgent coronary artery bypass grafting as a means of coronary revascularization during STEMI is indicated in the following situations: [O’Gara 2013;26a(e103)]

1. Patients with STEMI and coronary anatomy not amenable to PCI who have ongoing or recurrent ischemia, cardiogenic shock, severe HF or other high-risk features (class I recommendation for urgent CABG)
2. Patients with STEMI at time of operative repair of mechanical defects such as ventricular septal defect or papillary muscle rupture (class I recommendation)

In patients with STEMI who do not have cardiogenic shock and are not candidates for PCI or fibrinolytic therapy, emergency CABG within 6 hours of symptom onset may be considered. [O’Gara 2013;26a(e103)] CABG is not indicated when there is a small area of myocardium in jeopardy and the patient is stable.

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