5 Acute Coronary Syndrome, part 3 Flashcards
How to administer aspirin
Give aspirin, ≥160 mg and preferably 320 mg if naive of aspirin, [chewed and swallowed], ASAP to all patients with STEMI, NSTEMI, and UA
In patients with STEMI, aspirin alone reduces relative mortality rate by 23%
MOA of aspirin
Aspirin doses >162 mg cause immediate, near-complete inhibition of thromboxane A2.
Remarks on Aspirin and its contraindications
Due to the benefits during ACS, do not withhold eaerly aspirin from patients with minor contraindicaitons (vague allergy, hx of remote peptic ulcer, or GI bleeding)
Other antiplatelet agents such as clopdiogrel are alternatives if true allergy or active peptic ulcer disease exists.
Remarks on dosing of clopidogrel
For patients undergoing urgent PCI, 600 mg is superior to 300 mg in preventing postprocedure myocardial infarction.
A clopidogrel dose range of 300 to 600 mg in patients with unstable angina/NSTEMI [due to increased rate of bleeding in 600mg-dosing]
Because of an increased bleeding risk, withhold clopidogrel for ______ before CABG when possible
5 days
Examples of glycoprotein IIB/IIIA inhibitors
Abciximab (irreversible)
Eptifibatide (reversible)
Tirofiban (reversible)
Reversal of platelet inhibition after cessation of infusion is more rapid with the polypeptide or small-molecule agents eptifibatide or tirofiban, an advantage when bleeding complications occur
Remarks on GP IIb/IIIa inhibitors
- In those undergoig PCI, adding antiplatelet (in particular GP IIb/IIIa inhibitors) result in lower adverse events at 6 months
- Despite potential benefits, routine initiation of GP IIb/IIIa inh. in the ED is NOT recommended due to conflicting information about the timing of PCI after administrationa nd potential for bleeding.
- GP IIb/IIIa inhibiotrs should be given at the time of PCI; benefit prior to arrival in the cardiac catheterization laboratory is uncertain.
Optimally, cease unfractionated heparin after ______ hours of thearpy to reduce the risk of deveoping heparin-induced thrombocytopenia
48 hours
Remarks on enoxaparin
- Large clinical trials show that enoxaparin, rather than unfractionaed heparin, improved outcome in STEMI patients treated with aspirin and fibrinolysis
- Enoxaparin is NOT considered first-line antithrombin for patients receiving primary PCI for treatment of STEMI.
- However, in the event that a patient previously started on enoxaparin goes for PCI, enoxaparin should be continued
If CABG isplanned, hold LMWH heparin for _______
12 to 24 hours, bridging with unfractionaed heparin
Remarks on Fondaparinux
Factor Xa inhibitor
For NSTEMI patients in whom conservative management is to be used, the ACCP evidence-based CPG and ESC recommend fondaparinux over enoxaparin due to lower bleeding complications.
But still, ESC does not recommend fondaparinux in patients going for PCI
Significance of nitrates in ACS
When nitroglycerin is used in AMI patients not treated with thrombolytics, it reduces infarct size, improves regional function, and decreases the rate of cardiovascular complications.
The mortalty rate is lowered by 35% with the use of nitrates
In AMI, titrate IV nitroglycerin to BP reduction rather than to symptom (chest pain) resolution
The most serious side effect of nitroglycerin is
Hypotension, which may result in reflex tachycardia and worsening ischemia.
If nitroglycerin results in hypotension, stop the drug and administer fluid for blood pressure
Use nitroglycerin cautiously in patients with
inferior wall ischemia, because 1/3 of such patients might have RV involvement.*
Nitrates reduce preload and commonly trigger hypotension in this setting, worsening infarct.
* so get right-sided ECG, to determine RV infarction
Avoid nitrates in patients with ACS who recently received
a phosphodiesterase inhibitor for erectile dysfunction:
wihtin 24 hours of sildenafil use
or within 248 hours of tadalafil use
