Unstable angina/ NSTEMI resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Definition

Unstable angina is an unexpected chest pain that starts while resting or sleeping and could get worse with time, lasting at least 20 minutes up to half an hour. It is caused by a temporary reduced blood flow, resulting in a decreased of oxygen supply to the myocardial tissue.

Causes

Life Threatening Causes

• Reduced myocardial perfussion
• Mycordial infarction
• Cocaine-associated mycoardial infarction

Common Causes

• Atherosclerosis
• Non-occlusive thrombus

Management

Shown below is an algorithm summarizing the approach to unstable angina from the "2012 ACCF/AHA focused update of the guideline for the management of patients with unstable angina/non-ST-elevation myocardial infarction

Diagnosis

Characterize the symptoms: ❑Chest pain ❑ At rest ❑ Duration> 20 minutes ❑ Absence of physical exertion ❑ 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 blood pressure ❑ Measure heart rate ❑ Auscultation of murmurs ❑ CHF
Order labs and tests: ❑ EKG ❑ Bio-markers ❑ Troponin I ❑ CK-MB ❑ Creatinine ❑ Glucose ❑ Hemoglobin

Treatment

❑ Administer 300mg aspirin ❑ Administer oxygen in patients with saturation <90% ❑ Administer sub-lingual nitroglycerine (0.3, 0.4 or 0.6mg) ❑ Administer morphine IV initial dose 2-4 mg with increments of 2-8mg every 5 to 15 minutes ❑ Administer beta-blockers (unless contraindicated) ❑ Administer statins (80mg atorvastatin ) ❑ Initiate anti thrombotic therapy

Determine the risk of adverse coronary event (TIMI)

Low risk Initial conservative strategy

High risk Initial invasive strategy

❑ Administer 300mg of copidogrel ❑ Administer fondaparinaux OR UFH in case of renal failure

❑ Administer IV GP IIb/IIIa inhibitors (eptifibatide or tirofiban) OR ❑ Administer Bivalirudin

❑ Perform a stress test

❑ Angiography

Low risk

High risk

Negative

Positive

Recurrent symptoms?

❑ Continue aspirin ❑ Continue with clopidrogel or ticagelor for 12 months ❑ Discontinue GP IIb/IIIa inhibitors ❑ UFH (for 48hrs) or Enoxiparin (for 8 dyas)

No

❑ Heart failure ❑ Serious arrhythmias ❑ Subsequent ischemia

❑ Continue aspirin ❑ Continue with clopidrogel or ticagelor for 12 months ❑ Discontinue with GP inhibitors ❑ UFH (for 48hrs) or Enoxiparin (for 8 dyas)

PCI ❑ Administer clopidogrel 24 hrs before ❑ As as possible in no bleeding risk patients who are unstable or with high risk of isquemia ❑ Administer UFH (50-100 units/kg)

CABG ❑ Continue aspirin + UFH ❑ Discontinue clopidogel 5 days before ❑ Discontinue enoxiparin and fondaparinaux 12-24 hrs before ❑ Discontinue IV GP IIb/IIIa inhibitors 4 hrs bfore ❑ Discontinue bivalirudin 3 hrs before

Angiography

Negative

Positive

❑ Continue Aspirin ❑ Continue with clopidrogel or ticagelor for 12 months ❑ Discontinue with GP inhibitors ❑ UFH (for 48hrs) or Enoxiparin (for 8 dyas)

PCI ❑ Administer clopidogrel 24 hrs before ❑ As soon as possible in no bleeding risk patients who are unstable or with high risk of ischemia ❑ Administer UFH (50-100 units/kg)

CABG ❑ Continue aspirin + UFH ❑ Discontinue clopidogel 5 days before ❑ Discontinue enoxiparin and fondaparinaux 12-24 hrs before ❑ Discontinue IV GP IIb/IIIa inhibitors 4 hrs before ❑ Discontinue bivalirudin 3 hrs before

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

Do´s

• Administer 300 mg of clopidogrel as initial treatment instead of aspirin in case of gastrointestinal intolerance of hypersensitivity reaction.
• Oxygen must be administered in patients with arteria saturation less than 90% or in respiratory distress
• Administer sublingual nitroglycerin in patients with ischemic chest pain. IV should be administer in patients with persistent chest pain after three sublingual nitroglycerins.
• Nitroglycerin should be administer to all patients with hypertension or heart failure.
• Beta-bloquers should be administer to all patients with hypertension, tachycardia or ongoing chest pain.
• Statins should be administer to all patients with unstable angina. The recommendation is atorvastatin 80mg/day
• Non-steroidal anti-inflamatory drugs should be discontinued immediately.
• Patients 75 years and older have an increased risk of bleeding the administration of anti-platelet therapy should be cautions, except in high risk situations such as diabetes and prior myocardial infarction.
• P2Y12 platelet inhibitor therapy should be continued for 12 months with a maintenance dose of either:
  • Clopidogrel - 75mg per day
  • Prasogrel - 10mg per day
  • Ticagrelor - 90mg twice a day

Don´ts

• Do not administer IV GP IIb/IIIa inhibitors to patients with low risk of ischemic events or at high risk of bleeding, already with aspirin and P2Y12 receptor inhibitors therapy.
• Prasugrel is potentially harmful as part of a due anti-platelet therapy in patients who are planned for PCI, with prior history of strokes o TIAs.
• IV beta-blockers should not be administer to hemodynamically unstable patients.
• Patients under 60kg (132lbs) should not receive a complete dose of prasugrel (10mg), due to high exposure to the active metabolite. They should receive half the dose (5mg) although it has not be proved to be as effective as a complete dose.
• Do not administer fibrinolytic therapy to patients with unstable angina, as it is not beneficial.
• Abciximab should not be administer to patients not programmed for PCI.

References

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