What is the diagnosis and treatment for ST-Elevation Myocardial Infarction (STEMI)?

From the Guidelines

STEMI patients should receive immediate medical attention, starting with aspirin (162-325 mg) and antiplatelet therapy, followed by primary percutaneous coronary intervention (PCI) within 90 minutes of first medical contact, as this approach has been shown to significantly reduce morbidity and mortality 1.

Key Considerations

• Aspirin therapy should be administered as soon as possible, with a loading dose of 162-325 mg, to inhibit platelet aggregation and reduce the risk of further cardiac events 1.
• Primary PCI is the preferred reperfusion strategy, and should be performed within 90 minutes of first medical contact, to restore blood flow to the affected area of the heart and minimize damage 1.
• If PCI is unavailable, fibrinolytic therapy should be administered within 30 minutes of arrival, to dissolve the blood clot and restore blood flow to the heart 1.
• Additional medications, including anticoagulation with heparin, beta-blockers, and high-intensity statins, should be used to further reduce the risk of cardiac events and improve outcomes 1.

Treatment Approach

• The treatment approach for STEMI patients should be guided by the principles of rapid reperfusion, antiplatelet therapy, and anticoagulation, to minimize damage and improve outcomes 1.
• The choice of reperfusion strategy, whether primary PCI or fibrinolytic therapy, should be based on the individual patient's clinical presentation and the availability of resources 1.
• Patients who do not receive reperfusion therapy should receive anticoagulation therapy with low molecular weight heparin, and fondaparinux, to reduce the risk of further cardiac events 1.

Important Considerations

• STEMI patients who present late or are ineligible for reperfusion therapy should receive pharmacological nonlytic therapy, including anticoagulation and antiplatelet therapy, to reduce the risk of further cardiac events 1.
• The treatment approach for STEMI patients should be individualized, based on the patient's clinical presentation, medical history, and other factors, to optimize outcomes and minimize risks 1.

From the FDA Drug Label

5.5 Increased Risk of Heart Failure and Recurrent Ischemia when used with Planned Percutaneous Coronary Intervention (PCI) in STEMI. In a trial of patients with STEMI, there were trends toward worse outcomes in the individual components of the primary endpoint between TNKase plus PCI versus PCI alone (mortality 6.7% vs. 4.9%, respectively; cardiogenic shock 6.3% vs. 4.8%, respectively; and CHF 12% vs. 9.2%, respectively). In addition, there were trends towards worse outcomes in recurrent MI (6.1% vs. 3.7%, respectively; p = 0.03) and repeat target vessel revascularization (6.6% vs. 3.4%, respectively; p = 0.0045) in patients receiving TNKase plus PCI versus PCI alone [see Clinical Studies (14.1)]. In patients with large ST segment elevation myocardial infarction, physicians should choose either thrombolysis or PCI as the primary treatment strategy for reperfusion Rescue PCI or subsequent elective PCI may be performed after administration of thrombolytic therapies if medically appropriate; however, the optimal use of adjunctive antithrombotic and antiplatelet therapies in this setting is unknown.

The use of tenecteplase in patients with STEMI may increase the risk of heart failure and recurrent ischemia when used with planned PCI.

• Mortality rates were higher in patients receiving TNKase plus PCI compared to PCI alone (6.7% vs 4.9%).
• Cardiogenic shock and CHF rates were also higher in patients receiving TNKase plus PCI (6.3% vs 4.8% and 12% vs 9.2%, respectively).
• Recurrent MI and repeat target vessel revascularization rates were higher in patients receiving TNKase plus PCI (6.1% vs 3.7% and 6.6% vs 3.4%, respectively) 2. It is recommended that physicians choose either thrombolysis or PCI as the primary treatment strategy for reperfusion in patients with large ST segment elevation myocardial infarction.

From the Research

STEMI Management

• The management of STEMI patients is crucial in determining the outcome, with the goal of keeping time intervals between symptom onset and reperfusion therapy as short as possible 3.
• The first-line management of STEMI patients often determines if the outcome is life or death, with primary PCI being the preferred treatment if it can be performed within 120 minutes of first medical contact (FMC) 3, 4.
• If primary PCI is not possible within 120 minutes, thrombolysis should be initiated within 30 minutes after FMC, either in the EMS ambulance or in a nearby non-PCI hospital 3.

Antiplatelet Therapy

• Dual antiplatelet therapy (DAPT) with aspirin and a thienopyridine is mandatory for STEMI patients, with prasugrel being preferred over clopidogrel due to its faster onset of action and superior effectiveness 3, 5.
• Prasugrel has been shown to significantly reduce nonfatal myocardial infarction and stent thrombosis compared to clopidogrel 3.
• The use of oral P2Y12 inhibitors, such as prasugrel and ticagrelor, is recommended for STEMI patients undergoing primary PCI, with a loading dose of 60 mg for prasugrel and a maintenance dose of 10 mg/day 4, 5.

Reperfusion Therapy

• Primary PCI is the preferred reperfusion strategy for STEMI patients, with a goal of keeping the "door-to-balloon" time as short as possible 3, 6.
• If primary PCI cannot be performed within 120 minutes, fibrinolysis therapy should be administered to dissolve the occluding thrombus 6.
• The initiation of networks to provide around-the-clock cardiac catheterization availability and the generation of standard operating procedures within hospital systems have helped to reduce the time to reperfusion therapy 6.

Future Directions

• New advances in antithrombotic therapy and preventive measures have resulted in a decrease in mortality from STEMI, but a substantial amount of patients still experience recurrent cardiovascular events after STEMI 6.
• Future research is needed to establish which antiplatelet agents should be administered, when, and how, in the clinical setting of STEMI 5, 7.
• The potential anti-ischaemic benefits of potent antiplatelet agents will need to be balanced against their risk of increased bleeding 7.