Unstable angina/ NSTEMI resident survival guide

# Overview
Unstable angina and non ST elevation myocardial infarction (NSTEMI) belong to two different ends of the spectrum of acute coronary syndrome.  These conditions have a similar clinical presentation characterized by an acute onset of chest pain that starts on minimal exertion, rest or sleep, lasts at least 20 minutes (but usually less that half an hour) and, is not relieved by medications or rest.  NSTEMI is differentiated from unstable angina by the presence of elevated cardiac biomarkers secondary to myocardial injury. Unstabel angina and NSTEMI might not be differentiated early following the occurrence of symptoms because cardiac biomarkers may require a few hours to rise.

# Causes

## Life Threatening Causes
Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.  Unstable angina and NSTEMI are life-threatening conditions and must be treated as such irrespective of the causes.

## Common Causes

### Myocardial Infarction
- Atherosclerotic plaque rupture and subsequent coronary thrombus (most common cause)
- Coronary artery spasm
- Arrhythmia
- Post-myocardial infarction
- Post-percutaneous coronary intervention
Abrupt closure
Loss of side branch
Distal embolization
Restenosis
Stent thrombosis
- Abrupt closure
- Loss of side branch
- Distal embolization
- Restenosis
- Stent thrombosis
- Post-coronary artery bypass graft
Graft closure
New lesion in the graft
- Graft closure
- New lesion in the graft
For a complete list of causes, click here for unstable angina and here for NSTEMI.

# Ischemia-guided Strategy vs. Invasive Strategy
Shown below is a table that lists the factors that are associated with appropriate selection of invasive strategy vs. ischemia-guided strategy among patients with NSTE-ACS.
Adapted from Amsterdam et al. 2014 AHA/ACC Guideline for the Management of Patients with Non-ST-Elevation Acute Coronary Syndromes. J Am Coll Cardiol. 2014;64(24):e139-e228

# FIRE: Focused Initial Rapid Evaluation
A Focused Initial Rapid Evaluation (FIRE) should be performed to identify patients in need of immediate intervention. The following algorithm is derived from the 2014 AHA/ACC guideline for the management of patients with Non-ST-elevation acute coronary syndromes (either unstable angina or non-ST-elevation myocardial infarction).
Boxes in the red color signify that an urgent management is needed.

# Revascularization Therapy

# Pre-Discharge Care
Abbreviations: ACE: angiotensin converting enzyme; LVEF: left ventricular ejection fraction; PCI: percutaneous coronary intervention; PO: per os; VF: ventricular fibrillation; VT: ventricular tachycardia

# Dosing of Parenteral Anticoagulants During PCI

# 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 nitroglycerin.
- Discontinue NSAID drugs immediately.   
- If fondaparinux is chosen to be administered ad the anticoagulant therapy during PCI, co-administer another antocoagulant with factor IIa activity such as UFH.

# Don'ts
- Do not administer fondaparinux as the sola anticoagulant to support PCI in patients with NSTE ACS due to increased risk of catheter thrombosis.
- Do not administer anticoagulation therapy following PCI unless there is compelling reason to continue such therapy.
- 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 NSAIDs to patients post-NSTE ACS. Attempt managing musculoskeletal pains using either acetaminophen, non-acetylated salicylates, tramadol, or small doses of narcotics before considering NSAIDs (first consider non-selective NSAIDs then selective NSAIDs)
- Do not administer hormone therapy (estrogen with out without progestin) to patients for secondary prevention of coronary events in post-menopausal women.
- Do not administer vitamin supplements (e.g. vitamin E, C, beta-carotene, folic acid, or vitamin B6/B12) for secondary prevention of NSTE ACS.
- Do not administer prasugrel to patients with prior history of strokes or TIA.
- 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 not scheduled for PCI. 
- Do not administer 2 P2Y12 receptor inhibitors, even in the presence of hypersensitivity or GI interoperability to aspirin.