Unstable angina/ NSTEMI resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Andrea Tamayo Soto [2]; Rim Halaby, M.D. [3]

Definition

Unstable angina is an unexpected chest pain that starts on minimal exertion, rest or sleep, lasts at least 20 minutes up to half an hour and is not relieved by medications or rest. Unstable angina and non ST elevation myocardial infarction (NSTEMI) belong to two different ends of the spectrum of acute coronary syndrome. Unstable angina is differentiated from NSTEMI by the absence of elevated cardiac biomarkers.

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

• Cocaine-associated mycoardial infarction

Common Causes

• Atherosclerosis
• Non-occlusive thrombus

Management

Diagnostic Approach

Shown below is an algorithm depicting the diagnostic approach to unstable angina and NSTEMI based on the 2012 ACCF/AHA focused update of the guideline for the management of patients with unstable angina/non-ST-elevation myocardial infarction.

Characterize the symptoms: ❑ Chest pain ❑ Absence of physical exertion ❑ Duration> 20 minutes ❑ Radiation to the jaw or left arm ❑ No relief with medications ❑ No relief with rest ❑ Worse with time ❑ Nausea ❑ Vomiting ❑ Sweating
Obtain a detailed history: ❑ Age ❑ Previous MI ❑ Previous PCI or CABG ❑ Cardiac risk factors: ❑ Hypertension ❑ Diabetes ❑ Hypercholesterolemia ❑ Tobacco use
Examine the patient: ❑ Measure the blood pressure ❑ Measure the heart rate ❑ Auscultate the heart searching for murmurs ❑ Search for signs of CHF ❑ Decreased air entry in the lungs ❑ Edema in the extremities
Order labs and tests: ❑ EKG ❑ Biomarkers ❑ Troponin I ❑ CK-MB ❑ Creatinine ❑ Glucose ❑ Hemoglobin

Therapeutic Approach

Shown below is an algorithm depicting the therapeutic approach to unstable angina and NSTEMI based on the 2012 ACCF/AHA focused update of the guideline for the management of patients with unstable angina/non-ST-elevation myocardial infarction.

Initial Treatment ❑ Administer 300mg aspirin ❑ Administer oxygen in patients with saturation <90% ❑ Administer sublingual nitroglycerine, (0.4-0.8mg) ❑ Administer morphine IV (initial dose 2-4mg with increments of 2-8mg every 5 to 15 minutes) ❑ Administer beta-blockers (unless contraindicated) ❑ Administer statins (atorvastatin, 80mg) ❑ Administer antithrombotic treatment ❑ Fondaparinux, or ❑ UFH in case of renal failure

Determine the risk of adverse coronary event: ❑TIMI Score, or ❑HEART Risk Score, or ❑GRACE Risk Score

Low risk Initial conservative strategy

High risk Initial invasive strategy

Administer one of the following antiplatelet agents: ❑ Clopidogrel ❑ Loading dose (300 mg) ❑ Maintenance dose for up to 12 months (75 mg) ❑ Ticagrelor ❑ Loading dose (180 mg) ❑ Maintenance dose for up to 12 months (90 mg twice daily)

Administer one of the following antiplatelet agents: Before PCI ❑ P2Y12 receptor inhibitors ❑ Clopidogrel (600mg), or ❑ Ticagrelor (180mg), or ❑ IV GP IIb/IIIa inhibitors ❑ Eptifibatide ❑ Loading dose 180 mcg/kg IV bolus followed by another bolus after 10 minutes ❑ Maintenance dose 2 mcg/kg/min, or ❑ Tirofiban ❑ Loading dose 25 mcg/kg ❑ Maintenance dose 0.15 mcg/kg/min At the time of PCI ❑ P2Y12 receptor inhibitors ❑ Clopidogrel (600mg), or ❑ Ticagrelor (180mg), or ❑ Prasugrel (60 mg) ❑ IV GP IIb/IIIa inhibitors ❑ Eptifibatide ❑ Loading dose 180 mcg/kg IV bolus followed by another bolus after 10 minutes ❑ Maintenance dose 2 mcg/kg/min, or ❑ Tirofiban ❑ Loading dose 25 mcg/kg ❑ Maintenance dose 0.15 mcg/kg/min

Recurrent or worsening symptoms?

❑ Perform an angiography

❑ Recurrence of symptoms ❑ Heart failure ❑ Serious arrhythmia ❑ Subsequent ischemia

No recurrent symptoms

❑ Perform an angiography Administer upstream antiplatelet agent: ❑ P2Y12 receptor inhibitors ❑ Clopidogrel ❑ Loading dose (600 mg) ❑ Maintenance dose (75 mg), or ❑ Ticagrelor ❑ Loading dose (180 mg) ❑ Maintenance dose (90 mg twice daily), or ❑ IV GP IIb/IIIa inhibitors ❑ Eptifibatide ❑ Loading dose 180 mcg/kg IV bolus followed by another bolus after 10 minutes ❑ Maintenance dose 2 mcg/kg/min, or ❑ Tirofiban ❑ Loading dose 25 mcg/kg ❑ Maintenance dose 0.15 mcg/kg/min

❑ Perform a stress test

Low Risk

High Risk

❑ Perform an angiography

❑ Continue aspirin for life ❑ Continue P2Y12 receptor inhibitors up to 12 months ❑ Clopidogrel (75mg once a day), or ❑ Ticagrelor (90mg twice a day) ❑ Discontinue GP IIb/IIIa inhibitors ❑ Continue antithrombotic therapy: ❑ UFH for 48 hours, or ❑ Enoxaparin for up to 8 days, or ❑ Fondaparinux for up to 8 days

Management Following Angiography

Findings on Angiography

Negative

Positive

PCI

CABG

Medical treatment

❑ Assess whether antiplatelet therapy is necessary ❑ Assess whether anticoagulation therapy is necessary

❑ Administer aspirin for life ❑ Administer a loading dose of P2Y12 receptor inhibitor (if not initially started) ❑ Clopidogrel 600 mg ❑ Ticagrelor 180 mg ❑ Prasugrel 60 mg ❑ Discontinue anticoagulant in uncomplicated cases

❑ Continue aspirin ❑ Discontinue IV GP IIb/IIIa inhibitors (4 hours before CABG) ❑ Manage the P2Y12 receptor inhibitor therapy (if CABG can be delayed) ❑ Discontinue clopidogrel (5 days prior to CABG) ❑ Discontinue ticagrelor (5 days prior to CABG) ❑ Discontinue prasugrel (7 days prior to CABG) ❑ Manage the antithrombotic therapy ❑ Continue UFH ❑ Discontinue enoxaparin (12-24 hours prior to CABG) ❑ Discontinue fondaparinux (24 hours prior to CABG) ❑ Discontinue bivalirudin (3 hours prior to CABG)

❑ Continue aspirin ❑ Administer a loading dose of P2Y12 receptor inhibitors (if not given before angiography) ❑ Clopidogrel (600mg), or ❑ Prasugrel (60mg) ❑ Discontinue IV GP IIb/IIIa inhibitors if started ❑ Manage antithrombotic therapy if given before angiography: ❑ Continue IV UFH for 48 hours or until discharge ❑ Continue enoxaparin for entire hospital stay, up to 8 days ❑ Continue fondaparinux for entire hospital stay, up to 8 days ❑ Discontinue bivalirudin or continue, 0.25mg/kg/hour for up to 72 hours

Thrombolysis in Myocardial Infarction (TIMI) Risk Score

Adults 65 years and older Previous coronary artery stenosis > 50% Cardiac catherterization Angioplasty or stent Bypass Myocardial infraction Cardiac risk factors - three or more Hypertension Diabetes High cholesterol MI in family history Tobacco history Use of aspirin the previous week Anginal events (two or more) in the previous day ST segment alteration (>1mm elevation or depression) Cardio bio-markers elevated

HEART Risk Score

Factors	Degree	Score
History	Highly suspicious Moderately suspicious Slightly suspicious	2 1 0
EGC	Significant ST depression Non-specific repolarisation disturbance Normal	2 1 0
Age	>65 years 45-65 years <45 years	2 1 0
Risk Factors	> 3 risk factors or history of atherosclerotic disease 1 or 2 risk factors No risk factors	2 1 0
Troponin	>3x the normal limit 1-3x the normal limit < the normal limit	2 1 0
		TOTAL

GRACE Risk Score

Factor	Categories	Score
Age (years)	<40 40-49 50-59 60-69 70-79 >80	0 18 36 55 73 91
Heart Rate (bpm)	<70 70-89 90-109 110-149 150-199 >200	0 7 13 23 36 46
Systolic Blood Pressure (mmHg)	<80 80-99 100-119 120-139 140-159 160-199 >200	63 58 47 37 26 11 0
Creatinine (mg/dL)	0-0.39 0.4-0.79 0.8-1.19 1.2-1.59 1.6-1.99 2-3.99 >4	2 5 8 11 14 23 31
Killip Class	Class I Class II Class III Class IV	0 21 43 64
Cardiac arrest at admission		43
Elevated Cardiac Bio-markers		15
ST-segment deviation		30

Do´s

• Administer a loading dose followed by a maintenance dose of clopidogrel, ticagrelor or prasugrel (if PCI is planned) as initial treatment instead of aspirin among patients with gastrointestinal intolerance or hypersensitivity reaction to aspirin.

• Administer sublingual nitroglycerin in patients with ischemic chest pain; however, administer IV nitroglycerin among patients with persistent chest pain after three sublingual nitroglycerins.

• Discontinue non-steroidal anti-inflamatory drugs immediately.

Don'ts

• Do not administer IV GP IIb/IIIa inhibitors to patients with low risk of ischemic events or at high risk of bleeding and who are already on aspirin and P2Y12 receptor inhibitors therapy.

• Do not administer prasugrel among patients with prior history of strokes o TIAs.

• Do not administer IV beta-blockers among hemodynamically unstable patients.

• Do not administer a complete dose of prasugrel among patients under 60kg (132lbs) due to high exposure to the active metabolite. They should receive half the dose of prasugrel although there is no evidence that half the dose is as effective as a complete dose.

• Do not administer fibrinolytic therapy to patients with unstable angina.

• Do not administer abciximab for patients nor scheduled for PCI.

References

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