Acute Coronary Syndromes Part 2 Flashcards
Antiplatelets
aspirin, P2Y12 inhibitors, GPIIb/IIIa inhibitors
Aspirin
aspirin 162 mg to 325 mg immediately upon presentation (MONA)
aspirin 81 mg/d to 325 mg/d should be continued indefinitely: 81 mg is the preferred dose; no evidence higher doses are more effective, conflicting evidence if higher doses increase bleeding rate
take with food
P2Y12 inhibitor
clopidogrel, ticagrelor, or prasugrel: Oral medications; Loading dose followed by maintenance dose in addition to aspirin; Dual antiplatelet therapy (DAPT) recommended for 12 months in STEMI or NSTEMI/UA; DAPT always ASA + P2Y12 inhibitor
cangrelor: IV option ($$); Platelet inhibition within 2 minutes; Use during PCI when patient did not receive loading dose P2Y12 inhibitor
Clopidogrel dosing
loading dose: 300-600 mg
maintenance dose: 75 mg daily
600 mg loading dose results in greater, more rapid, and more reliable platelet inhibition compared with a 300 mg loading dose
600 mg loading dose preferred except when using fibronolytic: fibrinolytic + age > 75 = no loading dose; fibrinolytic + age </= 75 = 300 mg loading dose
Ticagrelor dosing
loading dose: 180 mg
maintenance dose: 90 mg BID
Prasugrel dosing
loading dose: 60 mg
maintenance dose: 10 mg daily
Cangrelor dosing
30mcg/kg followed by 4mcg/kg/min x 2 hrs
maintenance dose: use an oral agent
Clopidogrel
- Prodrug- converted to active metabolite by CYP 2C19
- Most common (may be due to insurance coverage)
Ticagrelor effectiveness
- Greater inhibition of platelet aggregation than clopidogrel
- PLATO trial
- Clopidogrel vs ticagrelor
- Primary endpoint (death from vascular cause, MI, or stroke) decreased with ticagrelor
- Max dose of ASA is 81mg daily in combination with ticagrelor
- Side effects include dyspnea and ventricular pauses
Prasugrel effectiveness
Prasugrel: Not recommended for ischemia guided strategy (ticagrelor/clopidogrel preferred)
Greater inhibition of platelet aggregation than clopidogrel post PCI: TRITON-TIMI 38 trial
- Clopidogrel vs prasugrel, Primary endpoint (CV death, non-fatal MI, or non-fatal stroke) decreased with prasugrel; Higher bleeding risk
Contraindicated in patients with history of TIA/stroke
Not recommended in in patients ≥75 years old, <60kg or high bleeding risk Maintenance dose of 5 mg MAY be used if deemed necessary
Clopidogrel metabolism
prodrug
CYP2C19
Prasugrel metabolism
prodrug
CYP3A4
Ticagrelor metabolism
not a prodrug
CYP3A4
NSTEMI/UA P2Y12 inhibitor use
ischemia guided therapy: clopidogrel or ticagrelor preferred
early invasive strategy (PCI): any could be used, preference for ticagrelor or prasugrel
STEMI
fibrinolytic: clopidrogrel preferred
PCI: ticagrelor or prasugrel preferred
Drug eluting stent (DES) or bare metal stent (BMS)
DES may not be preferred if patient is unable to tolerate or comply with a
prolonged course of DAPT. Why? -DES associated with higher rate of late stent thrombosis (up to 12 months)
Aspirin patient counseling
need to take lifelong to prevent heart attack
take with food
risk of bleeding
P2Y12 inhibitor patient counseling
take with ASA for one year to prevent heart attack
risk of bleeding
ticagrelor: take 12 hrs apart
Signs and Symptoms of bleeding: minor
Bruising
Light nosebleeds
Bleeding gums when flossing
Signs and Symptoms of Bleeding: Major
Blood in urine
Blood in stool (often dark and tarry)
Coughing up blood (looks like coffee grounds)
Cut that won’t stop bleeding after putting strong pressure on it for 10 minutes
Coronary artery bypass graft
aspirin: Does not need to be held prior to CABG
P2Y12 inhibitors: Hold prior to elective CABG: Ticagrelor - 3 days; Clopidogrel - 5 days; Prasugrel – 7 days
* Hold for 24 hours prior to urgent CABG if possible
GP IIb/IIIa Inhibitors
Abciximab, eptifibatide and tirofiban: Potent IV antiplatelets given IN ADDITION to ASA and P2Y12
inhibitor; Given at the time of PCI - No benefit to starting “upstream” before PCI; Expensive
Not used routinely: Case by case basis; Increased risk of bleeding when add a third antiplatelet; Majority of trials conducted before DAPT was standard of care
GP IIb/IIIa Inhibitors - STEMI/NSTEMI
Consider on an individual basis at the time of PCI NSTEMI: high risk features such as positive troponin
STEMI: large thrombus burden
Inadequate P2Y12 inhibitor loading
“Bail out”
Use during procedure if thrombus develops or low blood after stenting
GP IIb/IIIa Inhibitors - contraindications
Different for each agent. If you are going to recommend, check for contraindications
Examples?: Active bleeding; Any history of hemorrhagic stroke; Severe uncontrolled hypertension (SBP >180 or DBP >110); Major surgery within 6 weeks; Dialysis
