Chest Pain in the Field: The 4 Questions That Make the Difference Between ACS and False Alarm

How EMS paramedics perform chest pain triage when there's no cardiologist beside them. The practical guide nobody teaches you.

Introduction

Eleven EMS calls per day for "chest pain". Of these, nine are benign. But what about the remaining 10%? It's an acute myocardial infarction (ACS - Acute Coronary Syndrome) and it needs you to arrive alive at the hospital.

Here's the problem: chest pain is the chameleon of emergency medicine. It could be a strained muscle, gastric irritation, pulmonary inflammation, costochondritis, or the coronary artery that's occluding right now, while you're talking to the patient.

You don't have real-time interpretable ECG in the ambulance. You don't have troponin, you don't have a cardiology consultation. You have 4 simple, intuitive, and scientifically validated questions, which with a 2-3 minute interview tell you whether you're facing an infarction or a false alarm.

This article is your practical toolkit.

Why Chest Pain Triage Is Difficult (And Why You Must Do It Well)

The Clinical Context

• Incidence: 5-9% of all Emergency Department visits are for chest pain
• Of these, 40% is ACS (true infarction or unstable angina)
• 60% is benign, but must still be triaged to rule out the threat
• Cost of error: Under-triage (not recognizing infarction) = death in ambulance; Over-triage (sending everyone to ED as red codes) = system congestion, delays for true emergencies

The Statistical Pitfalls

Medicine has documented that:

• Experienced paramedics recognize ACS 71-85% of the time on first triage – not bad, but there's room for improvement
• Women, elderly, diabetics have "atypical" presentations (less classic chest pain, more vague symptoms) – mortality in women with STEMI is double compared to men of the same age
• Elderly over 75 may present only dyspnea, confusion, general malaise – zero classic chest pain

You can't afford to make that mistake. Therefore: right questions, systematic approach.

The 4 Crucial Questions: OPQRST Adapted for the Field

OPQRST is an established anamnestic method (classic AMLS model) that allows you to gather structured information about chest pain:

• O = Onset (beginning)
• P = Provocation/Palliation (what worsens it, what improves it)
• Q = Quality (quality of pain)
• R = Radiation (radiation)
• S = Severity (severity)
• T = Time (duration)

For your context (ambulance, stressed patient, 2-3 minutes), the 4 TOP PRIORITY questions are those that allow you to identify red flags for ACS.

IMPORTANT: This is not a mathematical score to add up. These are clinical indicators - the more red flags you identify, the higher the probability of ACS. The goal is to recognize patterns, not calculate points.

Question #1: "When did it start, and how?"

[Onset + Time]

What you're looking for: Sudden vs gradual onset, context of occurrence.

Cardiac (ACS) – HIGH Probability

• Sudden onset, without warning:
• "It hurts while I'm resting / watching TV" → ACS
• "I was working and boom, pressure in my chest" → ACS
• "At night, I woke up like this" → ACS

• Onset during emotional stress:
• Strong argument, traumatic event → adrenaline release → ACS

• Started this morning and continues for hours (not episodic):
• Incessant pain (even if fluctuating) → ACS

Non-Cardiac – HIGH Probability

• Gradual onset, with movement:
• "I lifted a suitcase yesterday, today it hurts" → muscle
• "After a gym session" → tear, strain
• "Worsens when I stretch" → chest wall

• Episodic, passes on its own:
• "It hurts for 10 seconds, then passes" → costochondritis, herpes zoster
• "Worsens when I breathe deeply" → pleuritis, pericarditis (but the latter has sudden onset!)

How to ask it in the ambulance:

"Sir, tell me: what were you doing when the pain started? Were you resting or exerting yourself? Was it sudden, like lightning, or did it come slowly?"

ACS red flags:

• Sudden + at rest
• During intense emotional stress
• Continuous pain for hours

Low probability indicators:

• Gradual + associated with movement/physical exertion
• Episodic that passes on its own

Question #2: "What's the pain like? How would you describe it?"

[Quality]

This is where the English language becomes your best medical friend. Because ACS has a specific semiotics of language.

Cardiac (ACS): These Specific Terms

• "Pressure" / "Weight" / "Heaviness":
• This is the classic. It's not a stab, it's not a localized burning: it's like having an elephant sitting on the chest.
• Authentic example: "I feel like someone is sitting on me" = ALERT for ACS

• "Constriction" / "Tightness":
• Sensation of circular constriction around the thorax, like a "vice"

• "Deep burning" (not superficial):
• Burning inside the chest (retrosternal), not on the skin

• Attention: Women and atypical presentations:
• "Sense of malaise" (vague)
• "Difficulty breathing" (dyspnea is ACS!)
• "Pain in shoulder/neck/jaw" (atypical radiation)
• "Nausea with chest discomfort"
• "Heart feels like it's beating strangely" + chest discomfort

Non-Cardiac: These Specific Terms

• "Sharp" / "Stabbing" / "Shooting pain":
• Sharp pain, needle-like = musculoskeletal, herpes zoster, pleuritis
• It's NEVER classic ACS (except pericarditis, which has sudden onset + sharp pain)

• "Superficial burning":
• Burning on the skin, localized to 1-2 cm = chest wall, herpes zoster

• "Hurts like a bruise" / "Soreness":
• Contusion, muscle tear

• "Pain on swallowing":
• Esophagitis, gastrointestinal reflux

How to ask it:

"Sir, what does the pain feel like? Is it pressure, like you have weight? Or is it a sharp point? Is it like a vice or like burning?"

ACS red flags (specific terminology):

• Pressure / Heaviness / Constriction (most specific)
• Deep retrosternal burning
• In women: vague malaise, dyspnea, nausea + chest discomfort

Low probability indicators:

• Sharp / Stabbing / Shooting pains
• Superficial burning on the skin
• Bruise-like pain or soreness

Question #3: "Does it radiate anywhere? Where do you feel the pain besides the chest?"

[Radiation]

Radiation is the third diagnostic pillar. The heart doesn't have specific local pain receptors – the pain it feels "projects" along the spinal nerves to other areas.

Cardiac (ACS): These Radiations Are Red Flags

• Left arm (above all):
• Chest pain → left arm, left hand, fingers
• This is the classic teaching – and it's true
• Sensation of numbness/tingling in the left arm

• Neck / Jaw:
• Pain that "rises" from chest to neck, up to jaw/mandible
• Patient says: "It hurts from here (chest) to here (jaw)"

• Left shoulder (even without arm):
• Diffuse pain to shoulder-neck-thorax

• Epigastrium (pit of stomach):
• Pain descending toward upper abdomen
• Often confused with gastritis/reflux (diagnostic trap!)

• Back (dorsum):
• Thoracic pain radiating to the back, especially scapula
• Often means posterior ischemia

Non-Cardiac: These Radiations Suggest Otherwise

• Absence of radiation:
• Pain confined to 1 point = chest wall (costochondritis, intercostal)

• Unilateral radiation (always right, or always lower left):
• Pain remaining on one side = compressed intercostal nerve, herpes zoster

• Radiation along palpation:
• Pain traveling down the left arm when you press the muscle = muscular trigger point, not cardiac

How to ask it:

"Sir, does the pain stay only in the chest or do you feel something in your arm too? Neck? Shoulder?"

ACS red flags (typical radiations):

• Left arm (most classic)
• Neck / Jaw
• Left shoulder
• Epigastrium (careful: can mimic gastritis!)
• Back / Scapula

Low probability indicators:

• Absence of radiation (pinpoint pain)
• Strictly unilateral radiation to the right
• Pain following muscular palpation

Question #4: "What else do you feel? Sweating, nausea, shortness of breath?"

[Associated Symptoms = the "Alarm Bell"]

These are the accompanying symptoms – the "triad" that transforms suspicion into certainty.

Cardiac (ACS): These Associated Symptoms

• Diaphoresis / Cold sweat:
• Visibly sweating patient, cold skin, chills
• It's not fever (warm sweat), it's the sympathetic system going into overdrive
• One of the most specific signs: if you see cold sweat + pressure chest pain = call the hospital immediately

• Dyspnea (shortness of breath):
• Short breath, gasping, sensation of suffocation
• Occurs because the heart is failing, the lungs are congesting (initial pulmonary edema)
• Particularly in women, elderly, diabetics

• Nausea / Vomiting:
• It's not gastritis: it's vagal stimulation from cardiac ischemia
• Patient says: "I have some nausea" + chest pain = red

• Anxiety / Sense of impending doom:
• Patient is visibly agitated, says "I think I'm really sick"
• It's not panic (which is agitation + fear), it's instinctive awareness that something serious is happening
• Called "sense of impending doom" in literature

• Palpitations / Arrhythmias:
• "I feel my heart skipping", "beating strangely", "tachycardia"
• Especially if new (not chronic)

Non-Cardiac: These Symptoms Suggest Otherwise

• Absence of associated symptoms:
• Isolated pain, calm patient, no sweating = low probability ACS
• Possible, but rare

• Cough, sputum, fever:
• Pneumonia, pleuritis (pulmonary inflammation)

• Pain on swallowing, difficulty swallowing:
• Esophagitis, reflux

• Pain worsening with palpation (press the chest, worsens):
• Chest wall

How to ask it:

"Sir, besides the pain, do you feel: cold sweat? Shortness of breath? Nausea? Heart beating strangely?"

ACS red flags (critical associated symptoms):

• Diaphoresis / Cold sweat (very specific)
• Dyspnea / Shortness of breath
• Nausea / Vomiting
• Sense of impending doom / Intense anxiety
• Palpitations / Arrhythmias

Low probability indicators:

• Total absence of associated symptoms
• Fever + cough (more suggestive of pulmonary cause)
• Pain worsening with palpation

Summary: Red Flags for ACS

How to Interpret the Signs

Don't add up points: observe the overall pattern.

Clinical Interpretation

HIGH probability ACS:

• 3+ red flags present
• Cold sweat + pressure pain + left arm radiation
• Any atypical presentation in woman/elderly/diabetic with sudden dyspnea

MEDIUM probability ACS:

• 1-2 red flags present
• Mixed pattern (some red flags + some low probability indicators)
• Doubtful interpretation → treat as potential ACS

LOW probability ACS:

• No red flags or only 1
• Pain reproducible with palpation
• Clearly musculoskeletal pattern

ATTENTION: Even with low clinical probability, if the patient has risk factors (smoking, diabetes, hypertension, family history) or if the ECG is abnormal → treat as potential ACS.

Case Study 1: The Woman "This Morning I Wake Up Bad"

Presentation: 64-year-old woman, hypertensive, with chest pain for 30 minutes.

Application of Questions:

Q1 - Onset: "This morning I woke up like this, without doing anything. It was at night, sudden" → 🚩 RED FLAG: sudden, at rest

Q2 - Quality: "It's like someone is sitting on my chest. Very strong pressure" → 🚩 RED FLAG: classic heaviness

Q3 - Radiation: "Yes, I feel it especially in my left arm. It's strange, it doesn't usually happen to me" → 🚩 RED FLAG: left arm radiation

Q4 - Associated: "I have some sweat... I feel bad, really. And some nausea, but no vomiting" → 🚩 RED FLAG: sweat + nausea

OVERALL ASSESSMENT: 4 red flags → HIGH PROBABILITY ACS

Interpretation and Action

Assessment: HIGH PROBABILITY ACS (STEMI or NSTEMI)

IMMEDIATE ACTIONS:

1. Positioning: Seated, calm, oxygen if SpO2 <95%
2. ECG immediately: Within 10 minutes (ideally 5 minutes). What to look for in the ECG?
3. ST elevation (elevation of ≥1 mm in at least 2 contiguous leads) → STEMI = Hospital with Cath Lab urgently
4. ST depression or T wave inversion → Suspected NSTEMI = Cardiac hospital
5. Normal ECG = Doesn't rule out ACS (troponin might still rise) – hospital anyway
6. Communication to Medical Control: "Control, we have a 64-year-old woman with sudden pressure chest pain, left arm radiation, cold sweat. Suspected ACS. ECG: [describe]. Where do we take her?"
7. Transport monitoring: Heart rate, blood pressure (every 5 min), SpO2, level of consciousness, pain
8. Don't give nitroglycerin in the field unless it's a specific protocol in your region + Medical Control authorizes

DESTINATION: Hospital with:

• If STEMI (ST elevation) → Center with Cath Lab (primary PCI)
• If suspected NSTEMI (no ST elevation but high clinical suspicion) → Cardiac hospital
• If normal ECG but suspicious clinical presentation → Hospital with troponin/triage

Case Study 2: The Man "It Hurts When I Stretch"

Presentation: 45-year-old man, construction worker, chest pain since morning after unloading material.

Application of Questions:

Q1 - Onset: "Yesterday I worked, unloaded bricks. This morning it hurts when I stretch or turn" → Low probability indicator: gradual, with movement

Q2 - Quality: "It's a sharp point. If I press here (palpates the intercostal), it worsens" → Low probability indicator: sharp, reproducible trigger point

Q3 - Radiation: "No, it stays only where I press. Doesn't radiate anywhere" → Low probability indicator: no radiation

Q4 - Associated: "No, I'm fine. No sweat, breathing normally, no nausea. Just discomfort" → Low probability indicator: no associated symptoms

OVERALL ASSESSMENT: 0 red flags, musculoskeletal pattern → LOW PROBABILITY ACS

Interpretation and Action

Assessment: LOW PROBABILITY ACS (But caution!)

ACTIONS:

1. Physical exam: Palpate the thorax – is the pain reproducible with compression? Yes? → Costochondritis / intercostal tear
2. ECG anyway: Even if low probability, if patient insists or has risk factors (smokes, hypertensive, diabetic), do quick ECG. If normal ECG → confidence increases
3. Communication to Medical Control: "Control, we have a 45-year-old man, chest pain reproducible with palpation, onset with movement, no radiation, no symptoms. Suspected musculoskeletal. ECG: normal. Managing as... green code?"
4. Destination: If high confidence → Observation Unit / Emergency Department for exclusion, no urgency. If abnormal ECG or risk factors → ED anyway

Case Study 3: The Elderly Woman "I Don't Really Know What I Feel"

Presentation: 78-year-old woman, diabetic, hypertensive, feels "strange", gasping, mild confusion, no classic chest pain.

Application of Questions:

Q1 - Onset: "Since this morning, suddenly. I was at home, without doing anything" → 🚩 RED FLAG: sudden

Q2 - Quality: "I don't know... I don't have pain. I just feel bad, tired, fatigued" → ATTENTION: atypical presentation, no classic pain

Q3 - Radiation: "No, nothing" → No radiation

Q4 - Associated: "Yes, short of breath. I can't catch my breath. I feel confused" → 🚩 RED FLAG: sudden dyspnea

OVERALL ASSESSMENT: 2 red flags + atypical presentation in high-risk patient → MEDIUM-HIGH PROBABILITY ACS

Interpretation and Action – ATTENTION!

Assessment: MEDIUM-HIGH PROBABILITY ACS (atypical presentation)

BUT: ATTENTION TO ATYPICAL PRESENTATIONS

In elderly women and diabetics, classic chest pain isn't always present. ACS can present as:

• Pure dyspnea (shortness of breath without pain)
• Confusion / altered state (in elderly)
• Weakness / asthenia
• Nausea without pain

In this woman's case:

1. ECG immediately (risk factors + sudden dyspnea = clinical red)
2. If ECG shows STEMI (ST elevation) → hospital with Cath Lab. If it shows NSTEMI pattern (ST depression) → cardiac. If normal but suspicious clinical presentation (dyspnea, confusion, diabetes) → cardiac urgent anyway
3. Communication to Medical Control: "Control, 78-year-old woman, diabetic, sudden dyspnea, confusion, no classic chest pain. Suspected atypical ACS based on clinical presentation. ECG: [describe]. Requesting cardiac centralization"
4. Oxygen (SpO2 >94%), continuous monitoring, IV access ready

ECG Basics for EMS Paramedics: What to Look For

You're not a cardiologist. You don't need to "read" the ECG. You need to recognize ONE thing: ST segment elevation.

What You'll See in the ECG

The ECG has 12 leads (12 "angles" of the heart):

• V1, V2, V3, V4, V5, V6 = ANTERIOR wall (LAD coronary)
• II, III, aVF = INFERIOR wall (RCA coronary)
• I, aVL, V6 = LATERAL wall (CX coronary)
• aVR = RIGHT wall (rare in EMS)

The ST Segment

On the ECG paper, you'll see waves (P, QRS, T) and flat intervals (ST). Normally, the ST segment is a flat line on the baseline (isoelectric line).

If the ST segment "rises" above the line (ST ELEVATION), in at least 2 contiguous leads (adjacent), it's STEMI.

If the ST segment "descends" below the line (ST DEPRESSION), it's suspected NSTEMI.

What to Do

If STEMI (ST elevation in V1-V4) = ANTERIOR = LAD coronary occluded = Cath Lab IMMEDIATELY

Example: V1, V2, V3, V4 show ST elevation

• ANTERIOR infarction = Large wall, maximum emergency
• Destination: Center with urgent catheterization

If STEMI (ST elevation in II, III, aVF) = INFERIOR = RCA coronary occluded = Cath Lab IMMEDIATELY (But caution: RV infarction?)

Example: II, III, aVF show ST elevation

• INFERIOR infarction = Potential RV infarction (watch for bradycardia/hypotension)
• Destination: Center with urgent catheterization

If NO ST elevation but suspicious clinical presentation = Suspected NSTEMI = Cardiac hospital (not absolute emergency, but urgent)

Final Checklist: Your Procedure in 10 Steps

Use this checklist when a "chest pain" call comes in:

TOTAL TIME: ~10-12 minutes from scene to hospital (depends on distance)

What NOT to Do (Common Errors)

• Don't wait for perfection: If you identify 3+ red flags, don't "let's see if it improves in 10 min". Go immediately.

• Don't give nitroglycerin in the field without ECG (it could be inferior STEMI with right ventricular infarction – nitro makes everything worse).

• Don't rule out ACS because "they're young": ACS can strike even a 30-year-old if they smoke + stress + hypertensive.

• Don't ignore women: Women with ACS have double mortality due to under-triage. Lower your threshold of suspicion.

• Don't do blind over-triage: Not all chest pains are red. But 3+ red flags are.

Practical Resources: What to Print and Keep in the Ambulance

Download and laminate:

1. Chest Pain Assessment Card (1 sheet): 4 OPQRST questions, red flags, clinical interpretation
2. ECG STEMI Recognition Card: Which lead = which artery = which urgency
3. Handoff Template: "Patient [M/F] [age], chest pain for [min], onset [description], quality [description], radiation [yes/no], associated [symptoms], red flags identified: [list], ECG [findings], Medical Control: destination [Y]"

Final Takeaway: 3 Things to Remember

1. The 4 OPQRST questions: They're your "stethoscope". Identify red flags - 3 or more = high probability ACS.
2. ECG within 10 minutes: Look for ST elevation. If present → Cath Lab. If not → cardiac but less urgency.
3. Watch for atypical presentations: Women, elderly, diabetics = dyspnea, confusion, nausea, without classic chest pain. Lower your threshold of suspicion.

Your competence in chest pain triage is not an "extra". It's the difference between a patient arriving at catheterization in 90 minutes (good outcome) vs 2 hours (worse outcome) or death in the field.

You know what? You are your patient's first cardiologist. Act accordingly.

Further Reading: The HEART Score

The red flags OPQRST approach we've described is a practical method for the field. For those who want to use a scientifically validated score, there is the HEART Score, developed specifically for chest pain in emergency settings.

What is the HEART Score?

The HEART Score stratifies the risk of major cardiac events within 6 weeks in patients with chest pain. It's based on 5 parameters:

• H = History (pain characteristics)
• E = ECG (electrocardiographic abnormalities)
• A = Age (patient's age)
• R = Risk factors (cardiovascular risk factors)
• T = Troponin (troponin levels)

Why didn't we use it in this article?

The HEART Score is excellent for the Emergency Department, where available:

• ECG interpretable by physician
• Troponin assay
• Time for complete evaluation

In EMS, you often don't have:

• Available troponin
• Time for complex calculations
• Specialized ECG interpretation

When to use the HEART Score?

If you work in:

• Advanced life support ambulance with physician on board
• First aid station with laboratory
• Emergency Department

You can calculate the complete HEART Score using tools like: https://www.emsy.io/en/calculators/prehospital-heart

Our Approach vs HEART Score

Our method based on OPQRST red flags is:

• ✅ Faster (2-3 minutes)
• ✅ Doesn't require laboratory
• ✅ Focused on history and clinical presentation
• ✅ Suitable for prehospital context

The HEART Score is:

• ✅ Scientifically validated with large numbers
• ✅ More precise in risk stratification
• ✅ Includes objective parameters (ECG, troponin)
• ❌ Requires more time and resources

In summary: use OPQRST red flags in the ambulance to quickly decide where to take the patient. The HEART Score will then be applied in the hospital for definitive risk stratification.

References

1. Del Rios M, et al. Part 1: Executive Summary: 2025 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2025;152(16_suppl_2):S284-S312. doi: 10.1161/CIR.0000000000001372
2. Backus BE, Six AJ, Kelder JC, et al. Chest pain in the emergency room: a multicenter validation of the HEART Score. Crit Pathw Cardiol. 2010;9(3):164-169. doi: 10.1097/HPC.0b013e3181ec36d8
3. Six AJ, Backus BE, Kelder JC. A prospective validation of the HEART score for chest pain patients at the emergency department. Int J Cardiol. 2013;168(3):2153-2158. doi: 10.1016/j.ijcard.2013.01.255
4. Poldervaart JM, Reitsma JB, Backus BE, et al. Effect of Using the HEART Score in Patients With Chest Pain in the Emergency Department: A Stepped-Wedge, Cluster Randomized Trial. Ann Intern Med. 2017;166(10):689-697. doi: 10.7326/M16-1600
5. Regione Lombardia. Manuale di Triage Intraospedaliero Regione Lombardia. 2022. Available at: https://simeup.it/wp-content/uploads/2022/12/Allegato-1-Manuale-di-Triage.pdf
6. FNOPI. I protocolli della Regione Lombardia - Il Soccorso Avanzato Preospedaliero con Infermieri. Available at: https://www.fnopi.it/archivio_news/attualita/1807/I%20protocolli%20della%20Regione%20Lombardia.pdf
7. Byrne RA, Rossello X, Coughlan JJ, et al. 2023 ESC Guidelines for the management of acute coronary syndromes. European Heart Journal. 2023;44(38):3720-3826. doi: 10.1093/eurheartj/ehad191
8. Cascioli F. Gestione assistenziale del paziente affetto da Sindrome Coronarica Acuta (SCA): ruolo e competenze dell'infermiere. Tesi di Laurea, Università Politecnica delle Marche, Facoltà di Medicina e Chirurgia. Anno Accademico 2017-2018. Available at: https://tesi.univpm.it/handle/20.500.12075/6430
9. Ministero della Salute. Linee di indirizzo nazionali sul triage intraospedaliero. Conferenza Stato-Regioni, 25 ottobre 2019. Available at: https://www.salute.gov.it/imgs/C_17_pubblicazioni_3145_allegato.pdf