Acute Coronary Syndrome Guidelines

Updated: Dec 11, 2016
  • Author: David L Coven, MD, PhD; Chief Editor: Eric H Yang, MD  more...
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Guidelines Summary


In 2015, the American College of Physicians (ACP) released guidelines on screening for coronary heart disease, including the following [15] :

  • There is no evidence that cardiac screening improves patient outcomes in asymptomatic, low-risk adults.
  • Potential harms of cardiac screening include false-positive results causing patients to undergo potentially unnecessary tests and procedures.
  • Among adults at low risk, prevalence of coronary heart disease is low, and cardiac screening is of low predictive value. Therefore, cardiac screening is of low yield, and the probability that positive findings will influence therapeutic decision making is low.
  • Clinicians should therefore emphasize strategies to reduce cardiovascular risk even further among low-risk adults by treating modifiable risk factors (smoking, diabetes, blood pressure, hyperlipidemia, overweight, and exercise).
  • Clinicians should not screen asymptomatic, low-risk adults for cardiac disease using resting or stress electrocardiography, stress echocardiography, or stress myocardial perfusion imaging.
  • Clinicians should conduct cardiovascular risk assessment with a global risk score combining individual risk factor measurements into a single quantitative estimate of risk.
  • The ACP recommendations do not apply to symptomatic patients or to screening athletes before participation in various events.

Management guidelines

The American College of Cardiology in conjunction with with the American Heart Association (AHA/ACC) and the European Society of Cardiology (ESC) have developed guidelines for management of patients with ST-segment elevation myocardial infarction (STEMI) [104, 105] and non-ST-elevation acute coronary syndromes (NSTE-ACS) [1, 106] which focus primarily on treatment in a hospital setting. Guidelines with specific recommendations for prehospital and emergency department (ED) management of patients with ACS were included in the 2015 revised international consensus guidelines on cardiopulmonary resuscitation and emergency cardiovascular care issued by the International Liaison Committee on Resuscitation (ILCOR). [107]  


The 2015 ILCOR recommendations for diagnostic interventions in ACS include the following:

  • Prehospital 12-lead electrocardiographic (ECG) acquisition with hospital notification should be obtained for adult patients with suspected STEMI (strong recommendation, low-quality evidence).
  • Computer-assisted ECG interpretation can be used as an adjunct to identify STEMI (weak recommendation, very-low-quality evidence), but it should not be used alone to rule out STEMI because of the poor sensitivity of the computer algorithms evaluated (weak recommendation, very-low-quality evidence).
  • For patients with suspected STEMI outside of a hospital setting, nonphysicians may perform ECG interpretation to recognize STEMI in a system where the false-positive (FP) and false-negative (FN) rates are low (weak recommendation, very-low-quality evidence).
  • When primary percutaneous coronary intervention (PPCI) is the planned strategy, prehospital activation of the catheterization laboratory for PPCI is preferred (strong recommendation, very-low-quality evidence).
  • The use of troponins at 0 and 2 hours as a stand-alone measure for excluding the diagnosis of ACS is strongly discouraged (strong recommendation, very-low-quality evidence). Excluding the diagnosis of ACS can be accomplished by combining negative high-sensitivity cardiac troponin (hs-cTnI) measured at 0 and 2 hours with low-risk stratification or by combining negative cardiac troponin I (cTnI) or cardiac troponin T (cTnT) measured at 0 and 3 to 6 hours with very low risk stratification (weak recommendation, low-quality evidence).

The 2014 AHA/ACC 2014 revision of their 2007 guidelines for the management of NSTE-ACS includes the following recommendations for evaluation of patients with suspected ACS, as summarized below. [106]

Class I

  • Risk stratify patients with suspected ACS based on the likelihood of ACS and adverse outcome(s) to decide on the need for hospitalization and to assist in the selection of treatment options. (Level of evidence: B)
  • Immediately refer patients with suspected ACS and high-risk features (eg, continuing chest pain, severe dyspnea, syncope/presyncope, or palpitations) to the emergency department (ED) and transport by emergency medical services when available. (Level of evidence: C)
  • In patients with chest pain or other symptoms suggestive of ACS, perform a 12-lead ECG and evaluate for ischemic changes within 10 minutes of the patient’s arrival at an emergency facility when possible. (Level of evidence: C)
  • Perform serial ECGs (eg, 15- to 30-minute intervals during the first hour) to detect ischemic changes if the initial ECG is not diagnostic but the patient remains symptomatic. (Level of evidence: C)
  • Obtain serial cardiac troponin I or T levels (when a contemporary assay is used) at presentation and 3 to 6 hours after symptom onset in all patients who present with symptoms consistent with ACS (to identify a rising and/or falling pattern of values). If the time of symptom onset is ambiguous, the time of presentation should be considered the time of onset for assessing troponin values. (Level of evidence: A)
  • Obtain additional troponin levels beyond 6 hours after symptom onset in patients with normal troponin levels on serial examination when changes on ECG and/or clinical presentation confer an intermediate or high index of suspicion for ACS. (Level of evidence: A)

Class IIa 

  • It is reasonable to give low-risk patients who are referred for outpatient testing daily aspirin, short-acting nitroglycerin, and other medications if appropriate (eg, beta blockers), with instructions about activity level and clinician follow-up. (Level of evidence: C)
  • Observe patients with symptoms consistent with ACS but without objective evidence of myocardial ischemia (nonischemic initial ECG and normal cardiac troponin) in a chest pain unit or telemetry unit with serial ECGs and cardiac troponin at 3- to 6-hour intervals. (Level of evidence: B)
  • For patients with suspected ACS who have normal serial ECGs and cardiac troponin levels, it is reasonable to have obtain a treadmill ECG (Level of evidence: A), stress myocardial perfusion imaging, or stress echocardiography before discharge or within 72 hours after discharge. (Level of evidence: B)
  • In patients with suspected ACS but a normal ECG, normal cardiac troponin levels, and no history of coronary artery disease (CAD), it is reasonable to initially perform (without serial ECGs and troponins) coronary computed tomography angiography to assess the coronary artery anatomy (Level of evidence: A) or rest myocardial perfusion imaging with a technetium-99m radiopharmaceutical to exclude myocardial ischemia. (Level of evidence: B)

The 2015 European Society of Cardiology (ESC) guidelines are in general agreement with the 2014 AHA/ACC guidelines. [1] Additional Class I recommendations are summarized below:

  • Base the diagnosis and initial short-term ischemic and bleeding risk stratification on a combination of the clinical history, symptoms, vital signs, other physical findings, and ECG and laboratory results. (Level of evidence: A) 
  • Measure cardiac troponin levels with sensitive or high-sensitivity assays, and obtain the results within 60 minutes of presentation. (Level of evidence: A) 
  • Perform a rapid rule-out protocol at 0 h and 3 h if high-sensitivity cardiac troponin tests are available. (Level of evidence: B) 
  • Perform a rapid rule-out and rule-in protocol at 0 h and 1 h if a high-sensitivity cardiac troponin test with a validated 0 h/1 h algorithm is available. Additional testing after 3–6 h is indicated if the first two troponin measurements are not conclusive and the patient's clinical condition remains suggestive of ACS. (Level of evidence: B) 
  • Perform continuous rhythm monitoring until the diagnosis of non–ST-elevation myocardial infarction (NSTEMI) is established or ruled out.(Level of evidence: C)
  • In the absence of signs or symptoms of ongoing ischemia, rhythm monitoring in unstable angina may be considered in selected patients (eg, suspicion of coronary spasm or associated symptoms suggestive of arrhythmic events).

In addition, the ESC guidelines find the Global Registry of Acute Coronary Events (GRACE 2.0) risk calculation provides the most accurate stratification of risk both on admission and at discharge. [1] However, the guidelines caution that although its value as a prognostic assessment tool is clear, the impact of risk score implementation on patient outcomes has not been adequately investigated. Bleeding risk can be stratified using the CRUSADE (Can Rapid risk stratification of Unstable angina patients Suppress ADverse outcomes with Early implementation of the ACC/AHA guidelines) risk score. [1]

Selection of management strategy

Determination of the preferred management strategy depends on the patient’s clinical characteristics and clinical risk. The AHA/ACC and ESC provide similar recommendations for selection of the preferred management stategy, which are summarized in Table 3, below. [1, 106]

Table 3.  Recommendations for Selection of Preferred Management Strategy (Open Table in a new window)

Preferred Strategy  Patient Characteristic/Clinical Risk
Immediate invasive strategy

(<2 hours)

Refractory angina
Signs or symptoms of heart failure, or new or worsening mitral regurgitation
Hemodynamic instability or cardiogenic shock
Recurrent angina/ischemia at rest, or with low-level activities despite intensive medical therapy
Sustained ventricular tachycardia or ventricular fibrillation
Ischemia-guided strategy Low-risk score (eg, TIMI 0 or 1, GRACE <109)
Low-risk Tn-negative female
Patient or physician preference in the absence of high-risk features
Early invasive strategy

(<24 hours)

GRACE score >140
Rise or fall in Tn compatible with MI
New or presumably new ST-segment depression
Delayed invasive strategy

(24-72 hours)

Diabetes mellitus
Renal insufficiency (GFR <60 mL/min/1.73m2)
Reduced LV systolic function (LVEF <40%)
Early postinfarction angina
PCI within 6 months
Prior CABG
GRACE score 109-140; TIMI Score ≥2
ACC/AHA = American College of Cardiology/American Heart Association; CABG = coronary artery bypass grafting; GRACE = Global Registry of Acute Coronary Events; LV = left ventricle; LVEF = left ventricular ejection fraction; PCI = percutaneous coronary intervention; TIMI = Thrombolysis in Myocardial Infarction Clinical Trial; Tn = troponin.

Initial hospital care

The 2014 AHA/ACC recommendations for initial hospital care are summarized below. [106]


Administer supplemental oxygen only when the oxygen saturation falls below 90%, respiratory distress is present, or other high-risk features for hypoxemia are present. (Class I; level of evidence C) 


Administer sublingual nitroglycerin (NTG) every 5 minutes up to 3 times for continuing ischemic pain, and then assess the need for intravenous (IV) NTG. (Class I; level of evidence: C) 

Administer IV NTG for persistent ischemia, heart failure (HF), or hypertension. (Class I; level of evidence: B) 

Nitrates are contraindicated with recent use of a phosphodiesterase inhibitor. (Class III; level of evidence: B)  


IV morphine sulfate may be reasonable for continued ischemic chest pain despite maximally tolerated anti-ischemic medications. (Class IIb; level of evidence: B)  

Nonsteroidal anti-inflammatories (NSAIDs) (except aspirin) should not be initiated and should be discontinued because of the increased risk of major adverse cardiac events (MACE) associated with their use. (Class III; level of evidence: B)  

Beta-adrenergic blockers

Initiate oral beta blockers in the absence of HF, low-output state, risk for cardiogenic shock, or other contraindications to beta blockade. (Class I; level of evidence: A)  

Use sustained-release metoprolol succinate, carvedilol, or bisoprolol for beta-blocker therapy in patients with concomitant NSTE-ACS, stabilized HF, and reduced systolic function (Class I; level of evidence: C)  

Re-evaluate to determine subsequent eligibility in patients with initial contraindications to beta blockers. (Class I; level of evidence: C)

It is reasonable to continue beta-blocker therapy in patients with normal LV function with NSTE-ACS. (Class IIa; level of evidence: C)

IV beta blockers are potentially harmful when risk factors for shock are present. (Class III; level of evidence: B)

Calcium channel blockers (CCBs)

Administer initial therapy with nondihydropyridine CCBs in patients with recurrent ischemia and contraindications to beta blockers in the absence of LV dysfunction, increased risk for cardiogenic shock, PR interval longer than 0.24 s, or second- or third-degree atrioventricular block without a cardiac pacemaker. (Class I; level of evidence: B)

Administer oral nondihydropyridine calcium antagonists in patients with recurrent ischemia after use of beta blockers and nitrates in the absence of contraindications. (Class I; level of evidence: C) 

CCBs are recommended for ischemic symptoms when beta blockers are not successful, are contraindicated, or cause unacceptable side effects. (Class I; level of evidence: C) 

Long-acting CCBs and nitrates are recommended for patients with coronary artery spasm. (Class I; level of evidence: C) 

Immediate-release nifedipine is contraindicated in patients with NSTE-ACS in the the absence of a beta blocker therapy (Class III; level of evidence: B) 

Cholesterol management

Initiate or continue high-intensity statin therapy in patients with no contraindications. (Class I; level of evidence: A) 

Obtain a fasting lipid profile in patients with NSTE-ACS, preferably within 24 hours of presentation. (Class IIa; level of evidence:C) 

Angiotensin-converting enzyme (ACE) inhibitors

Class I

ACE inhibitors should be started and continued indefinitely in all patients with a left ventricular ejection fraction (LVEF) below 40% and in those with hypertension, diabetes mellitus, or stable chronic kidney disease (CKD), unless contraindicated. (Level of evidence: A)

Use angiotensin receptor blockers (ARBs) in patients with heart failure or MI with an LVEF below 40% who are ACE inhibitor intolerant. (Level of evidence: A)

Use aldosterone blockade in post–MI patients who are without significant renal dysfunction or hyperkalemia who are receiving therapeutic doses of ACE inhibitor and beta blockers and have an LVEF below 40%, diabetes mellitus, or heart failure. (Level of evidence: A)

Antiplatelet therapy

Recommendations for initial antiplatelet/anticoagulation therapy in patients with NSTE-ACS are summarized below. [106]


Non–enteric-coated, chewable aspirin (162 mg to 325 mg) should be given to all patients without contraindications as soon as possible after presentation, and a maintenance dose of aspirin (81 mg/d to 325 mg/d) should be continued indefinitely. (Class I; level of evidence A) 

In patients who are unable to take aspirin because of hypersensitivity or major gastrointestinal (GI) intolerance, administer a loading dose of clopidogrel followed by a daily maintenance dose. (Class I; level of evidence B) 


Administer anticoagulation, in addition to antiplatelet therapy, for all patients, irrespective of the initial treatment strategy. Treatment options include the following (all Class I):

  • Subcutaneous (SC) enoxaparin for the duration of hospitalization or until PCI is performed (Level of evidence: A)  
  • Bivalirudin until diagnostic angiography or PCI is performed in patients with early invasive strategy only (Level of evidence: B)
  • SC fondaparinux for the duration of hospitalization or until PCI is performed (Level of evidence: B)
  • IV unfractionated heparin (UFH) for 48 h or until PCI is performed (Level of evidence: B)

IV fibrinolytic treatment is not recommended in patients with NSTE-ACS. (Class III, level of evidence: A)

Dual antiplatelet therapy

In 2016, the ACC/AHA released updated guidelines on duration of dual antiplatelet therapy (DAPT) in patients with coronary artery disease. In this focused update, the term and acronym DAPT is used to specifically to refer to combination antiplatelet therapy with aspirin and a P2Y12 receptor inhibitor (clopidogrel, prasugrel, or ticagrelor).

Key recommendations for patients with NSTE-ACS or STEMI treated with DAPT are summarized below. [108]

Class I

For all patients treated with DAPT, a daily dose of aspirin 81 mg (range, 75 mg to 100 mg). (Level of evidence: B-R)

After implantation with a bare metal stent (BMS) or drug-eluting stent (DES), administer P2Y12 inhibitor therapy (clopidogrel, prasugrel, or ticagrelor) for at least 12 months. (Level of evidence: B-R)

For patients who subsequently undergo coronary artery bypass grafting (CABG) after coronary stent implantation, resume P2Y12 inhibitor therapy postoperatively so that DAPT continues until the recommended duration of therapy is completed. (Level of evidence: C-EO)

In patients who undergo CABG, resume P2Y12 inhibitor therapy after CABG to complete 12 months of DAPT therapy. (Level of evidence: C-LD) 

Patients with STEMI treated with fibrinolytic therapy should be continue P2Y12 inhibitor therapy (clopidogrel) for a minimum of 14 days (Level of evidence: A) and, ideally, at least 12 months. (Level of evidence: C-EO)

Class IIa

After coronary stent implantation, it is reasonable to use ticagrelor in preference to clopidogrel for maintenance P2Y12 inhibitor therapy. (Level of evidence: B-R)

After coronary stent implantation in patients who are not at high risk for bleeding complications and who do not have a history of stroke or transient ischemic attack (TIA), it is reasonable to choose prasugrel over clopidogrel for maintenance P2Y12 inhibitor therapy. (Level of evidence: B-R)

Class IIb

In patients treated with coronary stent implantation or fibrinolytic therapy who have tolerated DAPT without a bleeding complication and who are not at high bleeding risk, it may be reasonable to continue DAPT (clopidogrel, prasugrel, or ticagrelor) for longer than 12 months. (Level of evidence: A)

After DES implantation, patients who develop a high risk of bleeding, are at high risk of severe bleeding complications, or develop significant overt bleeding, it may be reasonable to discontinue P2Y12 inhibitor therapy after 6 months. (Level of evidence: C-LD)

Class III

Prasugrel should not be administered to patients with a prior history of stroke or TIA. (Level of evidence: B-R)

Concomitant use of proton pump inhibitors and thienopyridines

A 2010 consensus statement issued by the ACC, American College of Gastroenterology (ACG), and AHA addressed the issue of concomitant use of proton pump inhibitors (PPIs) and thienopyridine antiplatelet drugs. [109]  The reocmmendations are summarized below.

Clopidogrel reduces major cardiovascular (CV) events compared with placebo or aspirin.

Dual antiplatelet therapy with clopidogrel and aspirin, compared with aspirin alone, reduces major cardiovascular events and coronary stent thrombosis, but it is not routinely recommended for patients with prior ischemic stroke because of the risk of bleeding.

Clopidogrel alone, aspirin alone, and their combination are all associated with increased risk of GI bleeding.

Patients with prior GI bleeding are at highest risk for recurrent bleeding on antiplatelet therapy. Other clinical characteristics that increase the risk of GI bleeding include advanced age; concurrent use of anticoagulants, steroids, or NSAIDs including aspirin; and Helicobacter pylori infection. The risk of GI bleeding increases as the number of risk factors increases.

Use of a PPI or histamine H2 receptor antagonist (H2RA) reduces the risk of upper GI bleeding compared with no therapy. PPIs reduce upper GI bleeding to a greater degree than do H2RAs.

PPIs are recommended to reduce GI bleeding among patients with a history of upper GI bleeding. PPIs are appropriate in patients with multiple risk factors for GI bleeding who require antiplatelet therapy.

Routine use of either a PPI or an H2RA is not recommended for patients at a lower risk of upper GI bleeding.

Clinical decisions regarding concomitant use of PPIs and thienopyridines must balance overall risks and benefits, considering both cardiovascular and GI complications.

2015 ACC/AHA/SCAI focused update on primary percutaneous coronary intervention for patients with ST-elevation myocardial infarction

In 2015 the ACC, AHA, and Society for Cardiovascular Angiography and Interventions (SCAI) issued revised recommendations for PCI in STEMI patients, summarized below. [110]

Class IIb

PCI should not be performed in a noninfarct artery at the time of primary PCI in patients who are hemodynamically stable. (Level of evidence: B)

PCI of a noninfarct artery may be considered in selected patients with multivessel disease who are hemodynamically stable, either at the time of primary PCI or as a planned staged procedure. (Level of evidence: B-R)

The usefulness of selective and bailout aspiration thrombectomy in patients undergoing primary PCI is not well established. (Level of evidence: C-LD)

Class III

Routine aspiration thrombectomy before primary PCI is not useful. (Level of evidence: A)

Hospital discharge and follow-up

Selected Class 1 recommendations for post-hospital care from the 2014 AHA/ACC guidelines are summarized below. [106]

Inpatient medications to control ischemia should be continued after hospital discharge in patients with NSTE-ACS who do not undergo coronary revascularization, patients with incomplete or unsuccessful revascularization, and patients with recurrent symptoms after revascularization. Titration of the doses may be required. (Level of evidence: C)

All patients should be given sublingual or spray NTG with verbal and written instructions for its use. (Level of evidence: C)

Before hospital discharge, patients should be informed about symptoms of worsening myocardial ischemia and Ml, and they should be given verbal and written instructions about how and when to seek emergency care for such symptoms. (Level of evidence: C)

For post–NSTE-ACS patients who have initial angina lasting more than 1 minute, it is recommended that NTG (1 dose sublingual or spray) be taken if angina does not subside within 3 to 5 minutes; patients or bystanders should call 9-1-1 immediately to access emergency medical services. (Level of evidence: C)

If the pattern or severity of angina changes, suggesting worsening myocardial ischemia (eg, pain is more frequent or severe or is precipitated by less effort or occurs at rest), patients should contact their clinician without delay to assess the need for additional treatment or testing. (Level of evidence: C)

Before discharge, patients should be educated about modification of cardiovascular risk factors. (Level of evidence: C)