Non-ST-elevation myocardial infarction: Difference between revisions
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===Types of Myocardial Infarction===
===Types of Myocardial Infarction===
:Type 1:  Ischemic myocardial necrosis due to plaque rupture ( ACS)
:'''Type 1:''' Ischemic myocardial necrosis due to plaque rupture ( ACS)
:Type 2:  Ischemic myocardial necrosis due to supply-demand mismatch, e.g.  coronary spasm, embolism, low or high blood pressures, anemia, or arrhythmias.
:'''Type 2:''' Ischemic myocardial necrosis due to supply-demand mismatch, e.g.  coronary spasm, embolism, low or high blood pressures, anemia, or arrhythmias.
:Type 3:  sudden cardiac death  (no cTr values)
:'''Type 3:''' sudden cardiac death  (no cTr values)
:Type 4:  procedure related, post PCI or stent thrombosis ( cTr > 5X Decision Level).
:'''Type 4:''' procedure related, post PCI or stent thrombosis ( cTr > 5X Decision Level).
:Type 5  post CABG  (cTr > 10X Decision Level).
:'''Type 5:'''   post CABG  (cTr > 10X Decision Level).


==Clinical Features==
==Clinical Features==
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*Non-STEMI ECG + positive troponin
*Non-STEMI ECG + positive troponin
*CK-MB and myoglobin are not helpful<ref>AHA ACA - NSTEMI ACS Guidelines 2014[http://circ.ahajournals.org/content/130/25/e344 View Online]</ref>
*CK-MB and myoglobin are not helpful<ref>AHA ACA - NSTEMI ACS Guidelines 2014[http://circ.ahajournals.org/content/130/25/e344 View Online]</ref>
*Angiography indicated for:
**Recurrent angina/ischemia with or with out symptoms of CHF
**Elevated troponins
**New or presumably new ST-segment depression
**High-risk findings on noninvasive stress testing
**Depressed LV function
**Hemodynamic instability
**Sustained [[V-tach]]
**PCI within previous 6 mo
**Prior CABG


==Management==
==Management==
*Dual antiplatelet therapy is key
*Dual antiplatelet therapy and antithrombotic therapy is mainstay of treatment
**[[ASA]] + other agent (other agent depends on conservative vs interventional strategy)
*Medical management vs cath determined by level of risk for future cardiovascular events
***Medical management vs cath determined by level of risk for future cardiovascular events
 
===Antiplatelet===
*[[Aspirin]]
**Recommended dose is 325mg chewed
**Reduces death from MI by 12.5 → 6.4%
**Should be used in all ACS unless contraindicated (eg [[Anaphylaxis]])
**In pts with true ASA allergies, substitute [[Clopidogrel]]<ref>CAPRIE Steering Committee.. A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). CAPRIE Steering Committee. Lancet. 1996 Nov 16;348(9038):1329-39.</ref>
*[[Clopidogrel]] (see drug link for specific age and indication-related dosages)
**Give in addition to ASA
**Mortality benefit with NSTEMI (CURE trial: Decrease in cardiovascular death, MI or stroke by 9.3-11.5%)
**Main risk and contraindication is bleeding
*GPIIb/IIIa Inhibitors
**Eptifibatide, abciximab, tirofiban
**Benefit only for patients undergoing PCI
**Administer at time of PCI, not in the ED
 
===Antithrombotics===
*Give heparin or enoxaparin along with ASA (Class 1A evidence)
*[[Enoxaparin]] (Lovenox)
**1mg/kg subq BID
**AHA recommends for moderate & high risk [[Unstable angina]]/NSTEMI unless CABG within 24hr
**Safer than UFH
**ESSENCE trial showed 20% decrease in death, MI or urgent revascularization with LMWH
**Adjust for CrCl<30ml and extremes of weight
**No need to monitor labs
*Unfractionated Heparin
**Bolus 60-70u/kg (max 5000) followed by infusion of 12-15u/kg/hr (max 1000/hr), goal ptt 45-75s
**Consider if patient likely to undergo PCI/CABG within 24hr of admission or in setting of renal failure
*Hirudin
**Approved only for patients with [[HIT]]


===Anti-ischemia===
===Anti-ischemia===
#[[Oxygen]]
#[[Oxygen]]
#*ACC recs O2 for sats <90% (evidence indeterminate)
#*ACC recs O2 for sats <90% (evidence indeterminate)
#[[Nitrates]]
#[[Nitrates]] (decrease preload)
#*Administer sublingual NTG every 5 min # 3 for continuing ischemic pain and then assess need for IV NTG (AHA ACA Level I)
#*Administer sublingual NTG every 5 min # 3 for continuing ischemic pain and then assess need for IV NTG (AHA ACA Level I)
#*No shown decrease in MACE
#*No shown decrease in MACE
#*Use cautiously in inferior MI or if on sildenafil
#*Use cautiously in inferior MI or if on sildenafil
#**Decreases preload
#*B-block to avoid reflex tachycardia
#Analgesia
#Analgesia
#*[[Morphine]] (AHA ACA Level IIb)
#*[[Morphine]] (AHA ACA Level IIb)
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#*Reduces pain and theoretically can decrease HR, SBP and O2 demand
#*Reduces pain and theoretically can decrease HR, SBP and O2 demand
#*Correct hypomagnesiemia
#*Correct hypomagnesiemia
===Antiplatelet===
#[[Aspirin]]
#*Recommended dose is 325mg chewed
#*Reduces death from MI by 12.5-6.4%
#*Should be used in all ACS unless contraindicated (eg [[Anaphylaxis]])
#**In pts with true ASA allergies, substitute [[Clopidogrel]]<ref>CAPRIE Steering Committee.. A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). CAPRIE Steering Committee. Lancet. 1996 Nov 16;348(9038):1329-39.</ref>
#[[Clopidogrel]] (see drug link for specific age, indication related dosages)
#*Give in addition to ASA
#*Mortality benefit with NSTEMI
#*Main risk and contraindication is bleeding
#*CURE trial: Decrease in cardiovascular death, MI or stroke by 9.3-11.5%
#GPIIb/IIIa Inhibitors
#*Eptifibatide, abciximab, tirofiban
#*Benefit only for patients undergoing PCI
#**Administer at time of PCI, not in the ED
===Antithrombotics===
#Give heparin or enoxaparin along with ASA (Class 1A evidence)
#[[Enoxaparin]]
#*AHA recommends for moderate & high risk [[Unstable angina]]/[[NSTEMI]] unless CABG within 24hr
#*1mg/kg subq BID
#*Safer than UFH
#**ESSENCE showed 20% decrease in death, MI or urgent revasc with LMWH
#*Adjust for CrCl<30ml and extremes of weight
#*No need to monitor labs
#Unfractionated Heparin
#*Consider if patient likely to undergo PCI/CABG within 24hr of admission
#*Bolus 60-70u/kg (max 5000) followed by infusion of 12-15u/kg/hr (max 1000/hr), goal ptt 45-75s
#Hirudin
#*Approved only for patients with [[HIT]]


===Thrombolytics===
===Thrombolytics===
*Only useful for [[STEMI]]
*Not indicated (only useful for [[STEMI]])


===Angiography===
==Disposition==
Indicated for:
*Admit
#Recurrent angina/ischemia with or with out symptoms of CHF
#Elevated troponins
#New or presumably new ST-segment depression
#High-risk findings on noninvasive stress testing
#Depressed LV function
#Hemodynamic instability
#Sustained [[V-tach]]
#PCI within previous 6 mo
#Prior CABG


==Prognosis==
==Prognosis==
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==See Also==
==See Also==
*[[Acute Coronary Syndrome (Main)]]
*[[STEMI]]
*[[Unstable Angina]]
*[[Cocaine Chest Pain]]
*[[Unstable Angina - NSTEMI Guidelines]]
*[[Unstable Angina - NSTEMI Guidelines]]
*[[Hirudins]]
*[[Acute coronary syndrome (main)]]
*[[ST-segment elevation myocardial infarction (STEMI)]]
*[[Unstable angina]]
*[[Cocaine-associated chest pain]]


==External Links==
==External Links==
*[http://www.mdcalc.com/timi-risk-score-for-uanstemi/ MDCalc - TIMI Risk Score for UA/NSTEMI]
*[http://www.mdcalc.com/timi-risk-score-for-uanstemi/ MDCalc - TIMI Risk Score for UA/NSTEMI]
==References==
==References==
<references/>
<references/>

Revision as of 02:02, 27 June 2017

Background

  • 33% with confirmed MI have no chest pain on presentation (especially older, female, DM, CHF)
  • 5% of NSTEMI will develop Cardiogenic Shock (60% mortality)
  • Age >65 with MI and anemia had 33% reduction in 30 day mort if transfused to keep HCT >30
  • Association between quantity of troponin and risk of death
  • NSTEMI includes Type 2 -Type 5 biomarker elevations

Types of Myocardial Infarction

Type 1: Ischemic myocardial necrosis due to plaque rupture ( ACS)
Type 2: Ischemic myocardial necrosis due to supply-demand mismatch, e.g. coronary spasm, embolism, low or high blood pressures, anemia, or arrhythmias.
Type 3: sudden cardiac death (no cTr values)
Type 4: procedure related, post PCI or stent thrombosis ( cTr > 5X Decision Level).
Type 5: post CABG (cTr > 10X Decision Level).

Clinical Features

Risk of ACS

Clinical factors that increase likelihood of ACS/AMI:[1][2]

Clinical factors that decrease likelihood of ACS/AMI:[3]

  • Pleuritic chest pain
  • Positional chest pain
  • Sharp, stabbing chest pain
  • Chest pain reproducible with palpation

Gender differences in ACS

  • Women with ACS:
    • Less likely to be treated with guideline-directed medical therapies[4]
    • Less likely to undergo cardiac catheterization[4]
    • Less likely to receive timely reperfusion therapy[4]
    • More likely to report fatigue, dyspnea, indigestion, nausea or vomiting, palpitations, or weakness,[4] although some studies have found fewer differences in presentation[5]
  • More likely to delay presentation[4]
  • Men with ACS:
    • More likely to report central chest pain

Factors associated with delayed presentation[4]

  • Female sex
  • Older age
  • Black or Hispanic race
  • Low educational achievement
  • Low socioeconomic status

Differential Diagnosis

Chest pain

Critical

Emergent

Nonemergent

Evaluation

  • Non-STEMI ECG + positive troponin
  • CK-MB and myoglobin are not helpful[6]
  • Angiography indicated for:
    • Recurrent angina/ischemia with or with out symptoms of CHF
    • Elevated troponins
    • New or presumably new ST-segment depression
    • High-risk findings on noninvasive stress testing
    • Depressed LV function
    • Hemodynamic instability
    • Sustained V-tach
    • PCI within previous 6 mo
    • Prior CABG

Management

  • Dual antiplatelet therapy and antithrombotic therapy is mainstay of treatment
  • Medical management vs cath determined by level of risk for future cardiovascular events

Antiplatelet

  • Aspirin
    • Recommended dose is 325mg chewed
    • Reduces death from MI by 12.5 → 6.4%
    • Should be used in all ACS unless contraindicated (eg Anaphylaxis)
    • In pts with true ASA allergies, substitute Clopidogrel[7]
  • Clopidogrel (see drug link for specific age and indication-related dosages)
    • Give in addition to ASA
    • Mortality benefit with NSTEMI (CURE trial: Decrease in cardiovascular death, MI or stroke by 9.3-11.5%)
    • Main risk and contraindication is bleeding
  • GPIIb/IIIa Inhibitors
    • Eptifibatide, abciximab, tirofiban
    • Benefit only for patients undergoing PCI
    • Administer at time of PCI, not in the ED

Antithrombotics

  • Give heparin or enoxaparin along with ASA (Class 1A evidence)
  • Enoxaparin (Lovenox)
    • 1mg/kg subq BID
    • AHA recommends for moderate & high risk Unstable angina/NSTEMI unless CABG within 24hr
    • Safer than UFH
    • ESSENCE trial showed 20% decrease in death, MI or urgent revascularization with LMWH
    • Adjust for CrCl<30ml and extremes of weight
    • No need to monitor labs
  • Unfractionated Heparin
    • Bolus 60-70u/kg (max 5000) followed by infusion of 12-15u/kg/hr (max 1000/hr), goal ptt 45-75s
    • Consider if patient likely to undergo PCI/CABG within 24hr of admission or in setting of renal failure
  • Hirudin
    • Approved only for patients with HIT

Anti-ischemia

  1. Oxygen
    • ACC recs O2 for sats <90% (evidence indeterminate)
  2. Nitrates (decrease preload)
    • Administer sublingual NTG every 5 min # 3 for continuing ischemic pain and then assess need for IV NTG (AHA ACA Level I)
    • No shown decrease in MACE
    • Use cautiously in inferior MI or if on sildenafil
  3. Analgesia
    • Morphine (AHA ACA Level IIb)
    • Do not use NSAIDs other than ASA (AHA ACA Level III: Harm)
  4. B-Blockers
    • No IV BB in ED (AHA ACA Level III: Harm), PO within 24 H
    • Goal HR is 50-60
    • Contraindicated if HR<50 or SBP<90, acute CHF, low flow state, or PR>240ms
    • Decreases progression from UA to MI by 13%
    • Decrease inotropic and chronotropic response to catechols
    • Use diltiazem if cannot use beta-blocker (nifedipine clearly harmful)
  5. ACE inhibitor
    • start short-acting (captopril) within 24hr of admission
    • Reduces RR of 30 day mortality by 7%
    • Those with recent MI (especially anterior) and LV dysfunction benefit most
  6. Transfusion
    • Transfuse to keep hemoglobin>10
  7. Magnesium
    • Reduces pain and theoretically can decrease HR, SBP and O2 demand
    • Correct hypomagnesiemia

Thrombolytics

  • Not indicated (only useful for STEMI)

Disposition

  • Admit

Prognosis

NSTEMI TIMI Score[8]

Used to estimate percent risk of all-cause mortality, new/recurrent MI, or need for revascularization at 14 days
  • Age >65 yrs (1 point)
  • Three or more risk factors for coronary artery disease: (1 point)
    • family history of coronary artery disease
    • hypertension
    • hypercholesterolaemia
    • diabetes
    • current smoker
  • Use of aspirin in the past 7 days (1 point)
  • Significant coronary stenosis (stenosis >50%) (1 point)
  • Severe angina (e.g., >2 angina events in past 24 h or persisting discomfort) (1 point)
  • ST-segment deviation of ≥0.05 mV on first ECG (1 point)
  • Increased troponin and/or creatine kinase-MB blood tests (1 point)
TIMI Risks
points % risk of mortality, MI, or need for revascularization
0 5%
1 5%
2 8%
3 13%
4 20%
5 26%
6 41%

See Also

External Links

References

  1. ↑ Body R, Carley S, Wibberley C, et al. The value of symptoms and signs in the emergent diagnosis of acute coronary syndromes. Resuscitation. 2010;81(3):281–286. PMID: 20036454
  2. ↑ Panju AA, Hemmelgarn BR, Guyatt GH, et al. The rational clinical examination. Is this patient having a myocardial infarction? JAMA. 1998;280(14):1256–1263. PMID: 9786377
  3. ↑ Swap CJ, Nagurney JT. Value and limitations of chest pain history in the evaluation of patients with suspected acute coronary syndromes. JAMA. 2005;294(20):2623–2629. PMID: 16304077
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Mehta LS, et al. Acute myocardial infarction in women: A scientific statement from the American Heart Association. Circulation. 2016; 133:916-947.
  5. ↑ Gimenez MR, et al. Sex-specific chest pain characteristics in the early diagnosis of acute myocardial infarction. JAMA Intern Med. 2014; 174(2):241-249.
  6. ↑ AHA ACA - NSTEMI ACS Guidelines 2014View Online
  7. ↑ CAPRIE Steering Committee.. A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). CAPRIE Steering Committee. Lancet. 1996 Nov 16;348(9038):1329-39.
  8. ↑ Antman, Elliot et al. The TIMI Risk Score for Unstable Angina/Non–ST Elevation MI A Method for Prognostication and Therapeutic Decision Making. JAMA. 2000;284(7):835-842. doi:10.1001/jama.284.7.835. PDF
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