19 - NSTEMI Flashcards
Risk factors for ACS
- Atherosclerosis
- Same risk factors as in other manifestations of ASCVD
Acute coronary syndrome (ACS)
- Spectrum of conditions involving abrupt reduction in coronary perfusion, usually due to thrombus formation secondary to unstable atherosclerotic plaque
- Divided into non-ST elevation acute coronary syndrome (NSTE ACS) & ST-elevation MI (STEMI)
- NSTE ACS further divided into unstable angina & non-ST elevation MI (NSTEMI)
Difference in ECG between NSTE ACS and STEMI
- NSTE ACE = lack of ST-segment elevation (may have ST depression and/or T-wave inversion)
- STEMI = ST-segment elevation in 2 or more contiguous ECG leads or new left bundle branch block (LBBB)
Difference in biomarkers between NSTE ACS and STEMI
- NSTE ACS = troponin elevated in NSTEMI, no in unstable angina
- STEMI = troponin elevated
Difference in physiology between NSTE ACS and STEMI
- NSTE ACS = partial occlusion of larger artery or total occlusion of small artery
- STEMI = total or near-total occlusion of larger artery
Difference in ischemia between NSTE ACS and STEMI
- NSTE ACS = partial-thickness myocardial ischemia w/ (NSTEMI) or w/o (UA) infarction
- STEMI = full-thickness MI
Difference in incidence between NSTE ACS and STEMI
- NSTE ACS = approx. 2/3 of ACS
- STEMI = approx. 1/3 ACS
Difference in ECG between unstable angina and NSTEMI
Both have presence or absence of markers of ischemia (ST depression or T-wave inversion)
Difference in biomarkers between unstable angina and NSTEMI
- Unstable angina = no significant troponin increase
- NSTEMI = troponin increased
Difference in physiology between unstable angina and NSTEMI
Both have partial occlusion of larger artery or total occlusion of small artery
Difference in ischemia between unstable angina and NSTEMI
- Unstable angina = ischemia but not infarction (yet)
- NSTEMI = ischemia w/ infarction
Difference in incidence between unstable angina and NSTEMI
- Unstable angina = minority
- NSTEMI = majority
ECG features of NSTE ACS
- ST-segment depression
- T-wave inversion
- Non-specific changes may be present; may be normal
How is NSTE ACS diagnosed?
- Symptomatic presentation similar to angina sx, although pain/discomfort unremitting (> 20 min) & may be more severe
- Px more likely to lack classic sx = elderly, diabetics, female, renal failure, & dementia
- 12-lead ECG (completed & read w/in 10 min); ST-depression and/or inverted T-waves
- Troponin measured 2x (perhaps more)
Goals of therapy for NSTE ACS
- Increase myocardial O2 supply (prevent thrombus progression)
- Decrease myocardial O2 demand
- Overall goal = minimize myocardial necrosis
Initial tx for acute management of NSTE ACS
- ASA + P2Y12 inhibitor (clopidogrel, ticagrelor)
- Anticoagulant (fondaparinux subcut, enoxaparin subcut, UFH infusion)
- Nitroglycerin subling prn
- O2 if O2 sat < 90%
- Morphine or fentanyl prn for severe pain
Antiplatelet therapy for initial tx of NSTE ACS
- ASA 160-325 mg once (chew & swallow, non-EC) then 81 mg daily
- P2Y12 inhibitor
- Clopidogrel 300-600 mg once (give 600 mg if urgent angiogram required), then 75 mg daily
- Ticagrelor 180 mg once, then 90 mg BID
- Prasugrel rarely used b/c dramatically increases surgical bleeding risk for 7 days after giving it
Anticoagulant therapy for initial tx of NSTE ACS
- Fondaparinux 2.5 mg subcut q24h if CrCl > 30 mL/min; avoid if weight > 120 kg
- Enoxaparin 1 mg/kg subcut q12h if CrCl > 30 mL/min; avoid if weight > 150-160 kg
- Unfractionated heparin (UFH) IV; preferred if CrCl < 30 mL/min or weight > 150-160 kg
Other agents for initial tx of NSTE ACS
- Nitroglycerin (0.4 mg spray or 0.3 mg tab subling q5min prn chest pain/discomfort) if SBP > 90 mmHg
- Morphine or fentanyl IV prn (only if needed; never use NSAIDs or COX-2 inhibitors)
- BZDs may be given to mitigate anxiety
Describe PCI for acute management of NSTE ACS
- Percutaneous coronary intervention (PCI)
- Allows for:
- Confirmation of diagnosis or to rule out a coronary origin
- Identification of culprit lesion(s)
- Assessment for PCI or CABG
- Stratify px short- & long-term risk
- If angiography identifies a culprit lesion & anatomy is amenable to PCI, one or more intracoronary stent(s) are placed
- 2 types of stents:
- Bare metal (more likely to have restenosis; require shorter minimum duration DAPT)
- Drug-eluting (DES) *most common (impregnated w/ antiproliferative drug to minimize restenosis; require longer minimum duration DAPT)
Describe CABG for acute management of NSTE ACS
- If anatomy is not amenable to PCI, coronary artery bypass grafting may be considered (approx. 10% of NSTE ACS may require urgent CABG)
- 3 types of grafts:
- Internal mammary (usually left internal mammary); most reliable, usually grafted to LAD
- Saphenous vein
- Radial artery
- P2Y12 inhibitor should be held prior to CABG if possible (clopidogrel x 5 days; ticagrelor x 5 days; prasugrel x 7 days)
- Anticoagulants should be managed as follows pre-CABG if possible
- UFH – continue uninterrupted
- Enoxaparin or fondaparinux – last dose 24 h pre-op
- CABG should be performed w/o delay in px w/ hemodynamic instability, ongoing MI, or very high-risk coronary anatomy, regardless of antiplatelet or anticoagulant tx
In-hospital goals of therapy for NSTE ACS
- Prevent recurrent ischemia
- Prevent cardiac arrhythmias, heart failure/cardiogenic shock, & other complications
- Initiate therapies for secondary prevention
In-hospital strategies for management of NSTE ACS
- Antithrombotics (antiplatelets & anticoagulants) part of initial tx
- Beta-blocker & statin (may be part of initial tx)
- ACE inhibitor or ARB
- Rapid acting nitroglycerin (part of initial tx)
- Maybe MRA
Antiplatelet therapy for in-hospital tx of NSTE ACS
- DAPT regardless of tx approach (PCI, CABG, or medical management)
- ASA 81 mg for maintenance dose & ticagrelor may be preferred P2Y12 inhibitor
- ASA + (clopidogrel or ticagrelor) are acceptable choices for medical management
- PPI indicated in combination w/ DAPT in px at risk of GI bleeds (history of GI ulcer/hemorrhage, anticoagulant therapy, chronic NSAID/corticosteroid use)
Anticoagulant therapy for in-hospital tx of NSTE ACS
- Anticoagulants d/c after revascularization
- For medical management:
- UFH continued for 48 h to 7 days
- Enoxaparin & fondaparinux continued for up to 8 days or hospital discharge
- Following d/c of full anticoagulation, initiate VTE prophylaxis & continue until discharge
Beta-blocker therapy for in-hospital tx of NSTE ACS
- Reduce early post-ACS mortality (reduce risk of ventricular arrhythmias)
- Recommended w/in 24 h of hospital admission for NSTE ACS in the absence of CIs or risk factors for cardiogenic shock (age > 70, HR > 110 beats/min, SBP < 120 mmHg)
- Avoid early beta-blockers in above px if LV function poor or unknown
- Preference for beta 1-selective agents (bisoprolol, metoprolol); carvedilol may also be used if LVEF = 40% or less
Statin therapy for in-hospital tx of NSTE ACS
- Indicated in all px w/ CAD
- Should be initiated early in hospital course (may be part of initial therapy)
- High-potency preferred, regardless of LDL-C
- Weeks to months to achieve significant benefit
ACE inhibitor/ ARB therapy for in-hospital tx of NSTE ACS
- ACE inhibitors strongly recommended in px w/
- LV systolic dysfunction (LVEF = 40% or less, hypertension, diabetes mellitus, chronic kidney disease)
- ARB recommend in px intolerant of ACE inhibitors (ex: cough)
- RAAS inhibition also used in absence of indications listed above for secondary prevention
- Caution for acute kidney injury, hyperkalemia, hypotension
Nitroglycerin therapy for in-hospital tx of NSTE ACS
- Rapid acting sublingual nitroglycerin may be used to treat intermittent ischemic pain in hospitalized NSTE ACS px
- *Doesn’t change outcomes
- Px w/ unresolving or recurrent ischemic pain require urgent revascularization
- IV infusion may allow for some delay until a pt is able to undergo revascularization if needed – still doesn’t change outcomes
Mineralocorticoid receptor antagonist (MRA) therapy for in-hospital tx of NSTE ACS
- Recommended in px w/ LV dysfunction (LVEF = 40% or less) & symptomatic heart failure or diabetes
- Eplerenone was agent studied for this indication; spironolactone likely has similar benefit
- Benefit long-term
Which medications should be given at discharge from hospital after an NSTE ACS?
All px should receive (unless CI) (Mnemonic AABCC – ASA, ACE/ARB, beta-blocker, cholesterol, clopidogrel or alternative)
- Antiplatelets (DAPT)
- Beta-blocker
- Statin
- ACE inhibitor/ARB
- Rapid-acting nitroglycerin
Goals of long-term therapy for secondary prevention of NSTE ACS
- Prevent harmful myocardial remodeling
- Stabilize existing atherosclerotic plaque & impair growth of new plaque
- Decrease risk of recurrent ASCVD events including ACS
- Decrease long-term morbidity & mortality
Which medications are used for secondary prevention of NSTE ACS?
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
Non-pharms for long-term therapy after NSTE ACS
- Cardiac rehab
- Smoking cessation
- Diet, exercise
Post-discharge LVEF assessment
Px w/ pre-discharge LVEF = 40% or less should have repeat ECG 6-12 weeks after MI, & after complete revascularization & optimal medical therapy
