20 - STEMI Flashcards
Describe the differences between stable angina, unstable angina, NSTEMI, and STEMI in regards to what happens in the arteries
- Stable angina = stable, fixed atherosclerotic plaque
- Unstable angina = unstable plaque (plaque disruption & platelet aggregation)
- NSTEMI = unstable plaque + thrombus; doesn’t fully occlude artery
- STEMI = unstable plaque + thrombus; large vessel will be completely or near-completely occluded, medium vessel will be completely occluded
Which conditions are considered ACS?
Unstable angina, NSTEMI, and STEMI
What are some differences w/ STEMI compared to NSTE ACS?
- STEMI = ~1/3 of ACS events
- Mortality higher for STEMI (~2x)
- Px w/ STEMI on average are younger, less likely to have significant multi-vessel CAD (tend to create faster growing plaques that are more likely to rupture)
What did STEMI used to be called?
Q-wave MI
ECG features of a STEMI
- New left bundle branch block (LBBB) or ST-segment elevation (2 or more contiguous leads)
- ST segment elevation is localizing (ie: indicates region, & often artery, involved)
How is STEMI diagnosed?
- Same as NSTEMI, except 12-lead ECG shows ST-segment elevation or new LBBB
- Troponin measured x 2 (possibly more) – b/c when vessel is still occluded, troponin will be slightly increased, but once vessel is opened troponin levels will skyrocket
Goals of therapy for acute management of STEMI
- Increase myocardial O2 supply (reperfusion – must be done emergently)
- Decrease myocardial O2 demand
- Overall = minimize myocardial necrosis
Overview of initial tx for acute management of STEMI
- ASA
- Metoprolol IV prn
- Nitroglycerin subling prn
- O2 if O2 sat < 90%
- Morphine or fentanyl prn for severe pain (**never use NSAIDs or COX-2 inhibitors)
- BZD may be given to mitigate anxiety
What other medications are given if a px is undergoing a primary PCI?
- P2Y12 inhibitor (clopidogrel, ticagrelor, prasugrel)
- Anticoagulant bolus (UFH, enoxaparin)
What other medications are given if a px is undergoing thrombolysis?
- P2Y12 inhibitor (clopidogrel)
- Anticoagulant bolus (UFH, enoxaparin)
When is an MI considered a completed infarct?
> 12 h from onset of sx
Describe the antiplatelet therapy for initial tx of STEMI
- ASA 160-325 mg po once (chew & swallow, non-enteric coated), then 81 mg po daily
- P2Y12 inhibitor will be determined by choice of reperfusion (primary PCI or thrombolysis)
Describe beta-blocker therapy for initial tx of STEMI. What is the purpose?
- Reduce ventricular arrhythmias (esp. w/ fibrinolysis)
- May be beneficial if hypertensive &/or tachycardic w/ ischemia
- Metoprolol 5 mg IV q5min prn x 3 IF:
- No contraindications (bradycardia, 2nd/3rd degree heart block, acute heart failure, severe asthma)
- SBP > 120 mmHg (infarct may cause hypotension)
- Caution in age > 70 years & w/ inferior STEMI (would cause high level heart block)
Describe reperfusion
- “Time is muscle” – most myocardial cell death happens w/in first 2 h
- Choice of reperfusion – primary percutaneous coronary intervention (PCI) or thrombolysis
- All px w/ ongoing sx of ischemia presenting w/in 12 h are eligible for emergent reperfusion
Describe primary percutaneous coronary intervention (PCI)
- Preferred strategy if able to be performed in
> 120 min (“door-to-balloon” time) from first medical contact (FMC)
– Ideally PCI should open artery w/in 60-90 min of FMC - Early angiography (w/in 24 h) recommended if sx completely relieved & ST-segment elevation completely normalized spontaneously or after nitroglycerin – this is an “aborted STEMI”
- Infarct-related artery is stented if possible, generally w/ drug-eluting stent (DES)
- Non-infarct-related arteries w/ severe plaque may be stented prior to discharge, or post-discharge
When should a PCI be performed after more than 12 h?
If pt has ongoing sx of ischemia, hemodynamic instability, or life-threatening arrhythmias
What is the pre-PCI antiplatelet therapy?
- ASA 160-325 mg po once
- P2Y12 inhibitor
- Clopidogrel 600 mg po once
- Ticagrelor 180 mg po once (may be preferred b/c works faster)
- Prasugrel 60 mg po once – only given after anatomy confirmed, so rarely used
- Glycoprotein IIb/IIIa inhibitors (abciximab, eptifibatide, tirofiban) may be used as “bailout” during PCI
What is the pre-PCI anticoagulation therapy?
- UFH bolus
- Enoxaparin 0.5 mg/kg IV bolus (no weight cap)
- Bivalirudin rarely used
- Anticoagulation d/c post-PCI unless otherwise indicated
- VTE prophylaxis should be given until discharge
What is another name for thrombolysis?
Fibrinolysis
When is thrombolysis used?
If time to PCI will be > 120 min (ex: pt presents to a rural hospital and must be transported to city for PCI)
Thrombolysis has limited benefit after __ h
3
What is the preferred agent for thrombolysis and why? How and when is it given?
- Tenecteplase (TNK) preferred agent
- Given as weight-based IV bolus (most favourable)
- Very high fibrin specificity & highest 90 min success rate
- Given ASAP after STEMI diagnosis (ideally less than 10 min; may be given pre-hospital by EMS)
What dose of TNK should be given to px 75 years and older?
1/2 dose
When is success of thrombolysis evaluated? What is considered a success?
- Evaluated 60-90 min post-dose
- Success = resolution of pain and over 50% resolution of ST-elevation
What should be done immediately after thrombolysis?
Pt should be transferred to PCI-capable centre (don’t wait to see if it works)
Primary concern w/ thrombolysis is _____
Bleeding
Which antiplatelets are used w/ TNK?
- ASA 160-325 mg po once (if not already given), 81 mg po daily
- Clopidogrel 300 mg po once, then 75 mg daily (if < 75 y/o); or 75 mg once, then 75 mg daily (if 75 years and older)
Which anticoagulants are used w/ TNK?
- Enoxaparin (preferred)
- If < 75 y/o – 30 mg IV once, then 15 min later 1 mg/kg subcut q12h (max. 100 mg/dose for first 2 doses)
- If 75 y/o or older – no bolus, 0.75 mg/kg subcut q12h (max 75 mg/dose for first 2 doses)
- UFH (preferred if Clcr < 30 mL/min or if > 150-160 kg
- Anticoagulants d/c following revascularization (successful PCI or CABG)
When should CABG be done for STEMI?
- If angiogram reveals anatomy not amenable to PCI, reperfusion w/ CABG must be considered
- Not all px are candidates
Which medications should be stopped prior to CABG?
- P2Y12 inhibitors (clopidogrel and ticagrelor x 5 days)
- Anticoagulants should be managed as follows (if possible):
- UFH & bivalirudin – continue uninterrupted
- Enoxaparin & fondaparinux – last dose 24 h pre-op
What is the general approach to in-hospital therapies for STEMI?
- Antithrombotics (antiplatelets, DAPT)
- Beta-blockers & statins may be part of initial tx
- ACE inhibitor or ARB
- Rapid-acting nitroglycerin
- Maybe MRAs
Antiplatelet therapy for STEMI in-hospital
- DAPT regardless if PCI or CABG
- ASA 81 mg maintenance dose (especially in combo w/ ticagrelor)
- Ticagrelor may be preferred P2Y12 inhibitor
- Px w/ completed infarct who don’t undergo revascularization may receive only ASA
- PPI indicated in combination w/ DAPT in px at risk of GI bleeds
Which px are at risk of GI bleeds?
- Hx of GI ulcer/hemorrhage
- Anticoagulent therapy
- Chronic NSAID/corticosteroid use
- 2 or more of: age >/ 65 years, dyspepsia, gastroesophageal reflux disease, H. pylori infection, chronic alcohol use
Anticoagulant therapy for STEMI in-hospital
- D/C after revascularization in absence of another indication
- Px w/ significant infarct & anterior STEMI should be assessed for LV thrombus (detectable 3-5 days post event) – if present, pt will require anticoagulation for at least 3 months (warfarin is standard)
Beta-blocker therapy for STEMI in-hospital
- Reduce early post-ACS mortality (reduce risk of ventricular arrhythmias)
- Oral BBs recommended w/in 24 h of hospital admission for STEMI (may be part of initial tx) in absence of CI or risk factors for cardiogenic shock (age > 70, HR > 110 beats/min, SBP < 120 mmHg – avoid early beta-blockers in these px if LV function poor or unknown)
- Preference for beta-1 selective agents (bisoprolol or metoprolol); carvedilol may be used if LVEF less than 40%)
Statin therapy for STEMI in-hospital
- Indicated in all px w/ CAD
- Should be initiated early (may be part of initial tx)
- High potency preferred, regardless of LDL
ACEi/ARB therapy for STEMI in-hospital
- ACEi strongly recommended in px w/:
- Left ventricular systolic dysfunction (LVEF 40%) or anterior infarct
- HTN
- Diabetes mellitus
- Chronic kidney disease
- ARB recommended in px intolerant of ACEi
- RAAS inhibition also used in absence of indications listed above for secondary prevention
- Caution for acute kidney injury, hyperkalemia, hypotension
Nitroglycerin therapy for STEMI in-hospital
- Rapid-acting sublingual nitroglycerin may be used prn for ischemic pain, doesn’t change outcomes
- Shouldn’t be required post-revascularization unless stable occlusive CAD remains
- Long-acting may be used to reduce pulmonary congestion in px w/ heart failure
MRA therapy for STEMI in-hospital
- Recommended in px w/ LV dysfunction & symptomatic heart failure or diabetes
- Eplerenone was agent studied for this indication, spironolactone likely has similar benefit
- Benefit is long-term only
- Caution for hyperkalemia & combination w/ ACEi or ARB
What is another name for MRAs?
Aldosterone antagonists
When can pericarditis occur?
Early infarct-related pericarditis may occur due to inflammation w/in pericardial sack
Tx for pericarditis
- ASA 650-975 mg po q6h (dose titrated down once sx controlled) w/ PPI; acetaminophen
- Don’t use non-ASA NSAIDs or corticosteroids (impair myocardial repair)
- Safety of colchicine unknown – may also interfere w/ myocardial repair
What are the medications given at discharge for a STEMI?
- Same as for NSTEMI
- Mnemonic (AABCC) – ASA, ACE/ARB, beta-blocker, clopidogrel or alternative, cholesterol (statin) + rapid-acting nitroglycerin
What is some general info to give px post-ACS?
- Ensure px/caregivers understand nature of disease before proceeding w/ explanation of tx (plaques in arteries are sometimes “juicy” and can “pop,” causing blood to stick to them, which blocks the artery…)
- Emphasize beneficial effects (purpose) of medications
- When explaining AEs, put risk into context
- Explain management
- Keep regimen to minimum level of complexity
Patient education - purpose of antiplatelets (DAPT)
- Make blood less sticky, which prevents clots from forming inside of stents or plaques in arteries
- Very important not to stop or interrupt taking clopidogrel, ticagrelor, or prasugrel early unless approved by a cardiologist
- Ensure intended duration of DAPT is clear
- Missing doses can result in second heart attack, especially if missed soon after 1st event
- ASA will be a lifelong medication b/c will lower risk of other blockages leading to clots w/in arteries and another heart attack
Patient education - adverse effects of antiplatelets (DAPT)
- Px may be at risk for minor bleeding or bruising; often termed “nuisance bleeding” & doesn’t require drug discontinuation
- Seek medical attention immediately if experiencing – severe stomach pain, bloody vomit, vomit that looks like coffee grounds, bloody/tarry black stools, bloody urine, excessive bruising (especially if unprovoked) – risk of this is low
- Don’t take any other medications (including OTC or herbal) containing ASA or that have known or potential antiplatelet effect
- Acetaminophen is analgesic of choice; NSAIDs should be avoided
- 1% of developing rash after starting clopidogrel; can be treated effectively w/ steroids w/o stopping clopidogrel or clopidogrel could be changed w/ alternative agent
- 13% chance of experiencing short episodes of dyspnea (shortness of breath) after starting ticagrelor; usually self-limiting & rarely require d/c
Patient education - purpose of beta-blockers
- Help prevent another heart attack
- Block effect of stress hormones on heart muscle & slow HR to help heart relax
- Protect against abnormal rhythms
- Protect heart muscle if it has been weakened
- If doses missed or drug is stopped w/o medical advice, HR may speed up or heart may flip into unhealthy rhythm
Patient education - adverse effects of beta-blockers
- May lower BP, sometimes causing dizziness, especially when going from lying or sitting to standing; usually gets better w/ time
- Some people may feel more tired when first start taking beta-blocker; usually gets better w/ time
Patient education - purpose of statins
- Slows/stops formation of plaques in arteries (preventing another heart attack)
- Should be taken life-long after a heart attack
Patient education - adverse effects of statins and when to take
- Large majority of people experience no side effects
- Some people experience new muscle soreness, achiness, cramping or weakness (similar to next-day muscle discomfort after hard work or heavy lifting); often can be resolved by lowering dose or changing to different statin
- Atorvastatin & rosuvastatin in morning; all others in evening
Patient education - purpose of ACEi/ARB
- Help prevent another heart attack
- “Unloads” heart & makes it easier to pump blood, mostly by lowering BP
- Strong protective heart that prevents heart muscle from weakening & helps a weakened heart muscle get stronger (other BP medications don’t have same protective effect)
Patient education - adverse effects of ACEi/ARB
- Will lower BP, can sometimes cause dizziness
- Non-productive cough or “tickle in the throat” is common w/ ACE inhibitors; may start early after starting the drug, or may take several months to develop
- May cause high potassium in blood
- Kidney function should be checked w/in 1-2 weeks of starting one of these drugs
Patient education - important info about nitroglycerin
Purpose is to buy time to get to the hospital – doesn’t fix the underlying problem if there is a new blockage in an artery
What are the long-term therapies after STEMI?
- Same as for NSTEMI
- Same medications as given as discharge
- DAPT continued preferably for 1 year regardless of tx approach; life-long ASA 81 mg daily continued following DAPT
- Ezetimibe = optional add-on in high-risk px willing/able to take
