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Antiplatelet therapy for patients with ACS without revascularization
Antiplatelet therapy for patients with ACS without revascularization. For patients with non-revascularized ACS, dual antiplatelet therapy should also be used for at least 12 months. If the risk of bleeding is low or there are no bleeding complications during treatment, it may be considered to extend to 30 months.
1. Cyclooxygenase COX-1 inhibitor
1) Aspirin irreversibly inhibits the enzyme and interferes with the production of thromboxane A2 by arachidonic acid, thereby inhibiting platelets. Attention should be paid to the risk of gastrointestinal bleeding and extracranial hemorrhage. Aspirin 75-150 mg/day is the safest dose.
2) Indobufen can reversibly inhibit the enzyme, and can also inhibit coagulation factors II and X. Compared with aspirin, this drug has less gastrointestinal reaction and low bleeding risk. It can be used as an allergy, intolerance or gastrointestinal tract to aspirin. Alternative therapy for patients with greater response, loading dose 200 mg, maintenance dose 100 mg, 2/day.
Recommendation: If there are no contraindications, all patients with acute coronary syndrome should take aspirin with the first dose of 150-300 mg (only for patients who have not taken aspirin before), and long-term use of 75-100 mg/day.
2. P2Y12 receptor inhibitor
1) Clopidogrel is a thiophene pyridine derivative. It is a prodrug and has no anti-platelet activity. It needs to undergo cytochrome P450 oxidation in the liver system. Its metabolites and P2Y12 receptors irreversibly bind to glycoprotein (GP) IIb. The activation of the /IIIa complex produces an antiplatelet effect.
2) Ticagrelor triazole pyrimidine antiplatelet drugs are non-prodrugs that bind reversibly to the P2Y12 receptor. They have the characteristics of fast onset and low mutation rate, which can cause adenosine-like effects (expanding blood vessels, leading to Difficulty breathing).
All patients with acute coronary syndrome should be combined with a P2Y12 inhibitor as soon as possible on the basis of aspirin. Ticagrelor (180 mg loading dose, 90 mg, 2/day maintenance) can be the first choice, and it is used when the risk of bleeding is high Clopidogrel (300 mg loading dose, 75 mg, 1/day maintenance).
• For patients with non-revascularized ACS, dual antiplatelet therapy should also be used for at least 12 months. If the risk of bleeding is low or there are no bleeding complications during treatment, it may be considered to extend to 30 months.
• 1 to 3 years after myocardial infarction with at least 1 high risk of ischemia (age greater than 65 years old, diabetes mellitus, at least 2 history of myocardial infarction, multivessel disease, high creatinine), aspirin combined with ticagrin may be considered Long-term treatment with Luo 60 mg, 2/day, up to 36 months, monitor for bleeding.
• The risk of bleeding is higher. Consider clopidogrel combined with aspirin for at least 1 to 3 months, followed by long-term aspirin or clopidogrel monotherapy, and monitor bleeding.
• When switching from clopidogrel to ticagrelor, the loading dose of ticagrelor (180 mg) is directly, without considering the dose of clopidogrel and the time of administration.
• When switching from ticagrelor to clopidogrel, a loading dose of clopidogrel 300-600 mg should be given 24 hours after the last dose of ticagrelor;
For patients who change their medication due to bleeding or fear of bleeding, give clopidogrel a maintenance dose of 75 mg/day 24 hours after the last dose of ticagrelor.
• When changing from clopidogrel 75 mg or ticagrelor 90 mg 2/day to ticagrelor 60 mg 2/day 1 year after myocardial infarction, the loading dose of ticagrelor is not required.
3. Glycoprotein (GP) IIb/IIIa receptor antagonist
Tirofiban can prevent fibrinogen from binding to platelet GP IIb/IIIa receptors, thereby blocking platelet cross-linking and aggregation.
Recommendation: For patients with high-risk NSTE-ACS, especially those with elevated troponin or diabetes, on the basis of oral antiplatelet drugs and heparin or low-molecular-weight heparin treatment, if the ischemic symptoms are still difficult to control, the bleeding risk should be fully assessed. In this case, tirofiban can be considered for no more than 36 hours, using 2.5 ug/kg intravenously, and then 0.15 ug/kg/min intravenously.
If the risk of bleeding is high, tirofiban should be used with caution or banned, hemoglobin and platelet counts should be monitored during medication, and bleeding should be closely monitored.
4. Phosphodiesterase inhibitors
Cilostazol inhibits phosphodiesterase III activity and adenosine reuptake, increases cADP concentration to play an anti-platelet effect, expands blood vessels, and inhibits pathological proliferation of the vascular intima. It is currently mainly used for the treatment of peripheral arterial occlusive diseases.
Recommendation: For patients with a higher risk of ischemia, if ticagrelor is contraindicated, consider aspirin combined with clopidogrel plus cilostazol triple therapy.
For patients with aspirin resistance or intolerance, cilostazol combined with clopidogrel or ticagrelor can be used for dual antiplatelet therapy.
(source:internet, reference only)