2022 ACC Expert Consensus Decision Pathway: Acute Chest Pain in the ED
Evaluation, Risk Stratification, and Disposition
Published: Journal of the American College of Cardiology (JACC), 2022 Organization: American College of Cardiology (ACC) DOI:10.1016/j.jacc.2022.08.750
The 2022 ACC Expert Consensus Decision Pathway provides practical guidance on the use of high-sensitivity cardiac troponin (hs-cTn) assays in emergency department evaluation of patients with possible acute coronary syndrome (ACS). Key updates include:
Emphasis on hs-cTn-based Clinical Decision Pathways (CDPs): Greater adoption of accelerated CDPs using hs-cTn with serial measurements at 0/1-hour and 0/3-hour intervals for rapid rule-out and risk stratification.
0-Hour Rule-Out Strategy: Single hs-cTn measurement below the limit of detection (LoD) in patients with symptom onset ≥3 hours allows safe discharge with high negative predictive value (NPV).
Sex-Specific 99th Percentile Thresholds: Recognition that sex-specific upper reference limits (URLs) improve diagnostic accuracy, particularly in women.
Chronic Kidney Disease Considerations: Validated pathways for patients with eGFR <60, with adjusted interpretation strategies.
Integration with Risk Scores: Modified HEART score and EDACS combine readily available clinical information with hs-cTn for efficient risk assessment.
Type 2 MI and Myocardial Injury Recognition: Structured approach to differentiation of acute MI subtypes and management of type 2 MI and chronic myocardial injury.
Observation Unit Protocols: Evidence-based strategies for intermediate-risk patients using serial cTn measurements and noninvasive testing.
Initial ED Assessment
Clinical History
Rapid focused assessment should address:
Symptom Characteristics: Onset, duration, quality (pressure, tightness, squeezing, heaviness, burning), location, radiation to arm/neck/jaw, exacerbating and relieving factors
Current Medications: Antiplatelet agents, anticoagulants, vasodilators, beta-blockers
Clinical Pearl: The term "chest discomfort" is more accurate than "chest pain" and includes diverse presentations. Ischemic symptoms may be atypical, particularly in women, elderly patients, and those with diabetes.
Physical Examination
While no findings are specific for ACS, high-risk examination findings warrant urgent evaluation:
Signs of hemodynamic instability (tachycardia, hypotension, altered mental status)
Evidence of heart failure (pulmonary rales, elevated JVP)
New cardiac murmurs
Signs suggesting alternative diagnoses (unequal pulses, BP differential, friction rub)
ECG: Focus on STEMI Recognition
Timing and Initial Interpretation
Class I A 12-lead electrocardiogram should be performed and interpreted within 10 minutes of ED arrival in all patients with symptoms concerning for ACS.
The initial ECG is critical for immediate identification of ST-segment elevation myocardial infarction (STEMI) or STEMI-equivalent patterns, which mandate emergent reperfusion therapy.
STEMI Recognition and Management
STEMI or STEMI-Equivalent ECG Findings:
ST-segment elevation ≥1 mm in contiguous chest leads (V1–V4) or limb leads (II, III, aVF, I, aVL)
New or presumed new left bundle branch block (LBBB)
ST-segment elevation in aVR with multilead ST-segment depression
Posterior STEMI patterns (dominant R wave in V1–V2, ST depression in V1–V3)
Wellens' sign (specific T-wave inversions in anterior leads)
Class I Patients with STEMI or STEMI-equivalent patterns should be managed according to the 2013 ACC/AHA STEMI Guideline with immediate reperfusion therapy (primary PCI or thrombolytics).
Non-STEMI ECG Patterns Concerning for Ischemia
ST-segment depression, T-wave inversions, or dynamic ST/T changes may indicate ischemia. Consider these findings in context of symptoms and proceed with hs-cTn-based CDP for risk stratification.
Nonischemic ECG
A normal or nonischemic ECG does not exclude MI or ongoing ischemia, particularly early in the presentation. These patients enter the accelerated CDP for further evaluation.
High-Sensitivity Cardiac Troponin (hs-cTn) Assays
Troponin Strategy and Advantages
High-sensitivity cardiac troponin T (hs-cTnT) or cardiac troponin I (hs-cTnI) assays are the preferred biomarkers for evaluation of possible ACS in the ED. Compared with conventional assays, hs-cTn assays:
Achieve greater sensitivity and precision
Detect lower cTn concentrations, allowing rule-out of MI with a single early blood draw
Support dynamic algorithms using serial measurements over 0–3 hours
Improve diagnostic accuracy when integrated with clinical assessment and ECG
Terminology: Definitions and Cutoffs
Upper Reference Limit (URL or 99th Percentile): The hs-cTn concentration above which values are considered abnormal. Sex-specific URLs are endorsed for enhanced diagnostic accuracy, particularly in women.
Limit of Detection (LoD): The highest hs-cTn concentration found when testing replicate samples known to contain no cTn. LoD is the most stringent rule-out threshold.
Limit of Quantification (LoQ): The lowest hs-cTn concentration that can be reported reliably. Clinical laboratories must be familiar with assay-specific LoQ and LoD values for their institution.
Key hs-cTn Clinical Decision Pathways (CDPs)
0-Hour Rule-Out (Single Blood Draw)
Class I For patients with symptom onset ≥3 hours prior to presentation and a single hs-cTn measurement ≤99th percentile URL with a nonischemic ECG and no other indicators of active ischemia, a 0-hour rule-out CDP allows safe discharge directly from the ED without additional testing.
0-Hour Rule-Out Algorithm
Chest pain onset ≥3 hours + hs-cTn ≤99th percentile URL + nonischemic ECG → Rule out low risk MI
Clinical judgment should always be applied; if ongoing symptoms or ECG changes concerning for ischemia, proceed to CDP
0/1-Hour Algorithm (ESC-Endorsed)
Class IIa The modified ESC 0/1-hour algorithm uses baseline hs-cTn and a 1-hour delta (change) in hs-cTn to classify patients as low risk (rule-out), intermediate risk (observation zone), or high risk (abnormal).
0/1-Hour Algorithm Interpretation:
Rule Out: 0-hour hs-cTn <LoD and 0/1-hour delta <B threshold
Observation Zone (Intermediate Risk): Other results; repeat at 3 hours and reassess
Abnormal/Higher Risk: If any values abnormal delta ≥C threshold
0/3-Hour Algorithm
Class IIa Identical to the 0/1-hour approach but with the second blood draw at 3 hours. This approach accommodates centers unable to consistently achieve 60-minute timing and maintains comparable safety profiles.
High-STEACS 3-Hour Algorithm
Class IIa The High-STEACS algorithm is designed for early presenters (symptom onset <3 hours). Initial hs-cTn ≤5 ng/L with a repeat measurement at 3 hours determines rule-out status. This approach is more conservative but benefits patients presenting very early in the infarction window.
Clinical Implementation Pearls
Assay-specific reference ranges, LoD, and LoQ values must be known and implemented
Timing of blood collection is critical; specimen collection windows must be accurately tracked
Clinical judgment should always supplement algorithmic interpretation
Integration with ECG findings, symptom duration, and risk factors optimizes patient triage
Risk Stratification for Disposition
Three-Tier Risk Approach
Patients are categorized as low risk (rule-out), intermediate risk (observation zone), or high risk (abnormal) using hs-cTn CDPs combined with clinical assessment and ECG findings.
Low-Risk/Rule-Out Patients
Class I Patients who meet low-risk criteria by hs-cTn CDP (single hs-cTn ≤99th percentile URL, nonischemic ECG, no ongoing chest discomfort) are eligible for safe discharge directly from the ED without additional testing.
Provided adequate outpatient follow-up is arranged
Follow-up within 3 days with PCP or cardiology is recommended
Risk-score application in selected low-risk patients may be considered
Intermediate-Risk Patients
Class I Patients in the observation zone (intermediate-risk group) comprise approximately 25–30% of those presenting with chest discomfort. These patients require observation and serial hs-cTn measurement at 3–6 hours along with risk stratification tools (modified HEART score, EDACS).
Intermediate-Risk Management:
Admit to observation unit (when available) or inpatient setting
Repeat hs-cTn at 3–6 hours after initial presentation
Apply risk stratification (modified HEART score ≤3 or EDACS <16)
Consider noninvasive testing (stress test, coronary CTA) for selected patients with low-risk features on repeat assessment
If repeat hs-cTn shows no significant change AND clinical reassessment is reassuring, consider discharge with close outpatient follow-up
High-Risk/Abnormal Patients
Class I Patients with elevated hs-cTn or dynamic changes in hs-cTn should be classified according to the Universal Definition of MI and managed as inpatient admissions with cardiology consultation.
Classify as type 1 MI (acute plaque rupture), type 2 MI (supply-demand mismatch), myocardial injury with and without necrosis
Pursue appropriate diagnostic testing (functional, anatomic, or invasive coronary angiography)
Initiate guideline-directed medical therapy and secondary prevention
HEART Score Application
The HEART score integrates five readily available clinical variables to predict 30-day major adverse cardiovascular events (MACE):
HEART Component
0 Points
1 Point
2 Points
History
Nontypical symptoms
Atypical symptoms
Typical ACS symptoms
ECG
Normal
Nonspecific changes
ST-segment changes
Age
<45 years
45–65 years
>65 years
Risk Factors
0–1 factors
2–3 factors
≥3 factors or prior CAD
Troponin
Normal
0.01–0.03 ng/mL
>0.03 ng/mL
HEART Score Risk Stratification:
Low Risk (Score 0–3): MACE <2%; consider discharge with close outpatient follow-up
Intermediate Risk (Score 4–6): MACE 2–20%; observation unit admission, serial troponin, risk reassessment
High Risk (Score 7–10): MACE >20%; inpatient admission, further diagnostic evaluation
Disposition, Follow-Up, and Treatment
Safe Discharge Criteria
Class I Patients meeting low-risk criteria via hs-cTn CDP may be safely discharged directly from the ED provided:
hs-cTn value(s) ≤99th percentile URL (or undetectable by LoD for 0-hour pathway)
Nonischemic ECG findings
No ongoing or recurrent chest discomfort concerning for ischemia
Ability to return to care if symptoms recur
Arranged follow-up with primary care provider (PCP) or cardiology within 3 days
Observation Unit Admission
Class IIa Observation unit admission is appropriate for intermediate-risk patients as an alternative to inpatient hospital admission. Observation protocols should include:
Serial hs-cTn measurements at 3–6 hours
Continuous cardiac monitoring in selected patients
Reassessment with risk scores (modified HEART, EDACS)
Noninvasive or invasive diagnostic testing as clinically indicated
Discharge planning with close outpatient cardiology follow-up (24–72 hours) for those with persistent low-risk features
Inpatient Hospital Admission
Patients with elevated hs-cTn, dynamic troponin changes, or high-risk features require hospital admission with:
Telemetry monitoring
Cardiology consultation
Guideline-directed medical therapy (antiplatelet, anticoagulation, beta-blockers, ACE inhibitors, statins)
Further diagnostic testing (functional, anatomic, or invasive coronary angiography)
Follow-Up After Discharge
Class I All patients discharged from the ED for possible ACS require close outpatient follow-up:
Low-Risk Patients: Follow-up with PCP within 3 days; specialist cardiology referral if concerning features identified during ED evaluation
Intermediate-Risk Patients (Post-Observation): Cardiology evaluation within 72 hours to finalize diagnostic testing and risk assessment
High-Risk or Admitted Patients: Cardiology consultation prior to or immediately after hospital discharge; arrangements for post-discharge follow-up and rehabilitation
Stress Testing vs. Coronary CTA: Patient Selection and Timing
Objectives of Secondary Testing
For intermediate-risk patients, the primary goals of noninvasive testing are to accurately diagnose or exclude clinically significant coronary artery disease (CAD) and to provide prognostic information to guide disposition and management decisions.
Stress Testing
Class IIa Exercise or pharmacologic stress testing (with imaging) is appropriate for intermediate-risk patients, particularly those with:
Class IIa Coronary computed tomography angiography (CTA) is an effective noninvasive alternative for intermediate-risk patients without known CAD. CTA advantages include:
High diagnostic accuracy for exclusion of significant CAD
Ability to assess noncalcified plaque and ischemia-relevant anatomy
Contrast allergy or inability to cooperate with imaging protocol
Timing of Noninvasive Testing
Testing should ideally be completed during the initial ED visit or observation unit stay when possible. Alternatively, testing may be arranged as outpatient follow-up with cardiology, provided intermediate-risk patients with negative repeat troponins have reassuring repeat risk assessment.
Non-ACS Diagnoses to Consider
A significant proportion of chest pain ED presentations are attributed to nonacute coronary causes. Rapid assessment should identify potentially life-threatening alternative diagnoses:
Use Wells PE scoring or revised Geneva score for pretest probability assessment
D-dimer testing or CT pulmonary angiography as clinically indicated
PESI score for risk stratification
Aortic Dissection
Classic presentation: sudden-onset, severe, tearing chest pain radiating to the back; blood pressure differential between limbs; aortic regurgitation murmur. High mortality if missed.
Urgent cross-sectional imaging (CTA, MRI, or TEE) if suspicion is high
Blood pressure and pulse control critical; avoid beta-blockers alone
Pericarditis
Presentation: pleuritic chest pain (positional, worse with recumbency), pericardial friction rub, elevated inflammatory markers (CRP, ESR). ECG shows PR depression and diffuse ST elevation.
Echocardiography to assess for pericardial effusion/tamponade
Small pneumothorax may be managed conservatively; larger or tension pneumothorax requires intervention
Musculoskeletal Pain
Reproducibility with palpation of chest wall, costochondritis, or musculoskeletal strain is common but should not delay evaluation of concerning presentations.
Gastroesophageal Reflux Disease (GERD)
Epigastric or substernal burning pain, often positional or food-related, should not exclude cardiac evaluation if associated symptoms or risk factors present.
Special Populations
Women
Class IIa Sex-specific 99th percentile upper reference limits for hs-cTn are endorsed to improve diagnostic accuracy in women. Women have higher prevalence of nonobstructive CAD and atypical symptom presentations.
Lower hs-cTn thresholds may improve sensitivity for MI detection in women
Consider functional or anatomic testing to exclude obstructive and nonobstructive CAD
Elderly Patients
Older patients frequently present with atypical symptoms, comorbidities, and baseline troponin elevations. Risk stratification requires integration of:
Diabetic patients often present with atypical or silent ischemia. Enhanced clinical vigilance is warranted. Risk stratification and diagnostic intensity should be escalated given underlying CAD burden.
Prior Revascularization
Patients with prior PCI or CABG have high likelihood of recurrent ACS. Escalate diagnostic intensity; consider early coronary angiography if elevated troponins or ischemic symptoms develop.
Cocaine Use
Cocaine induces coronary vasoconstriction and increases demand ischemia. ACS is possible even in young patients. Assess troponins, ECG, and consider coronary angiography if ischemia suspected.
Chronic Kidney Disease
Class IIa Validated hs-cTn pathways for eGFR <60 mL/min/1.73 m² include adjusted interpretation. Baseline troponin elevations are common; dynamic changes remain diagnostically important.
Clinical Do's and Don'ts
Do:
Perform 12-lead ECG within 10 minutes of ED arrival in all patients with symptoms concerning for ACS
Use high-sensitivity troponin assays when available; understand assay-specific LoD, LoQ, and 99th percentile URL
Apply hs-cTn-based CDPs (0-hour, 0/1-hour, 0/3-hour, or High-STEACS) to safely identify low-risk patients eligible for discharge
Obtain serial troponin measurements at 3–6 hours in intermediate-risk patients
Integrate clinical judgment with algorithmic findings; never rely on troponin or ECG alone
Arrange follow-up with PCP or cardiology within 3 days for all discharged patients
Consider noninvasive testing (stress test or CTA) for intermediate-risk patients based on clinical presentation and local expertise
Recognize STEMI patterns and activate emergent reperfusion pathways immediately
Don't:
Delay ECG performance awaiting troponin results or provider availability
Use conventional (non-hs) cTn assays for ED evaluation of possible ACS when hs-cTn is available
Discharge patients with ischemic ECG changes or elevated troponins without further evaluation and cardiology consultation
Discharge intermediate-risk patients without risk stratification tools, serial troponins, or observation unit admission
Ignore dynamic troponin changes (>20% relative change) even if absolute values remain below URL
Delay treatment of STEMI awaiting cardiac catheterization lab availability (activate emergent PCI or consider thrombolytics)
Assume normal ECG excludes ACS; nonischemic ECG findings remain compatible with acute MI or ischemia
Neglect consideration of alternative diagnoses (PE, dissection, pneumothorax) in differential diagnosis
Integrated Clinical Calculators
The following tools support risk stratification and diagnostic assessment in acute chest pain evaluation:
The 2022 ACC Expert Consensus Decision Pathway provides a systematic, evidence-based framework for safe and efficient evaluation, risk stratification, and disposition of patients presenting to the ED with possible ACS. Key recommendations include:
Clinical Pearl: High-sensitivity troponin-based clinical decision pathways, when integrated with clinical assessment, ECG findings, and risk stratification tools, enable rapid, safe identification of low-risk patients eligible for ED discharge and efficient triage of intermediate- and high-risk patients to appropriate hospital or observation unit care.
Implement hs-cTn assays with knowledge of assay-specific cutoffs and algorithms
Perform ECG within 10 minutes; recognize STEMI patterns for emergent reperfusion
Apply hs-cTn CDPs (0-hour, 0/1-hour, 0/3-hour, or High-STEACS) for efficient risk stratification
Use risk stratification tools (HEART score, EDACS) in parallel with biomarker evaluation
Observe intermediate-risk patients with serial troponin and noninvasive testing
Ensure organized follow-up within 3 days for all discharged patients
Maintain clinical vigilance for alternative diagnoses and atypical presentations
Tailor diagnostic intensity to special populations (women, elderly, chronic kidney disease, diabetes)
Remember that clinical judgment at the bedside remains indispensable; CDPs augment rather than replace clinical decision-making
This guideline is current as of 2022 and reflects the consensus of the ACC Solution Set Oversight Committee. Updates may be issued as new evidence emerges. Always consult the most current clinical practice guidelines and institutional protocols.