Acute Chest Pain Evaluation & Noninvasive Stress Testing
Exclude the six killers, risk-stratify the rest, then pick the stress test the ECG and legs allow
The first 10 minutes: exclude the killers
Approach. Every patient with chest pain is first screened for six conditions that kill quickly: acute coronary syndrome, aortic dissection, pulmonary embolism, tension pneumothorax, cardiac tamponade and esophageal rupture. Vital signs, a focused examination (BP in both arms, breath sounds, JVP, pulses, crepitus), a 12-lead ECG and a chest film come before any benign label.
The ECG clock. Obtain and interpret an ECG within 10 minutes of arrival. STEMI goes straight to reperfusion. If the first tracing is nondiagnostic and symptoms continue, repeat it every 15–30 minutes, add posterior leads (V7–V9) when ST depression in V1–V3 suggests posterior infarction, and record right-sided leads in inferior STEMI.
| Condition | Clues | First test or action |
|---|---|---|
| Acute coronary syndrome | Pressure radiating to arm or jaw, diaphoresis, exertional onset, ST changes | ECG in 10 minutes, serial hs-troponin; STEMI → reperfusion |
| Aortic dissection | Abrupt, maximal-at-onset tearing pain to the back; pulse deficit or inter-arm SBP difference >20 mmHg; new AR murmur; neurologic deficit; widened mediastinum | CT angiography if stable, TEE if unstable; no anticoagulation or lysis |
| Pulmonary embolism | Pleuritic pain, dyspnea, tachycardia, hypoxemia, DVT signs | Risk-guided D-dimer or CT pulmonary angiography |
| Tension pneumothorax | Absent breath sounds, tracheal deviation, hypotension, distended neck veins | Immediate needle or finger decompression, then chest tube — no imaging first |
| Cardiac tamponade | Beck triad (hypotension, JVD, muffled heart sounds), pulsus paradoxus >10 mmHg | Bedside echo → pericardiocentesis |
| Esophageal rupture | Pain after forceful retching, subcutaneous emphysema, pneumomediastinum | Water-soluble contrast CT or esophagram → NPO, antibiotics, surgery |
Dissection can extend into the right coronary ostium and mimic inferior STEMI; giving fibrinolytics or heparin before excluding it can be fatal.
Esophageal rupture pitfalls. Barium is avoided as the first contrast because it worsens mediastinitis if it leaks, and endoscopic air insufflation can enlarge the perforation.
Troponin and risk stratification
High-sensitivity troponin. Draw hs-troponin on arrival and again at 1–3 hours using a validated 0/1-hour or 0/2-hour pathway. Myocardial infarction requires a rise and/or fall with at least one value above the 99th-percentile upper reference limit plus clinical evidence of ischemia. When symptoms began more than 3 hours earlier, a single value below the limit of detection can rule out MI. A flat, stable elevation without a delta suggests chronic injury (CKD, heart failure), and dynamic rises also occur in PE, myocarditis, sepsis and takotsubo cardiomyopathy.
The HEART score. Each element scores 0–2:
- History — slightly, moderately or highly suspicious for ACS
- ECG — normal, nonspecific repolarization change, or significant ST depression
- Age — under 45, 45–64, or 65 and older
- Risk factors — none, one or two, or three or more (or known atherosclerosis)
- Troponin — normal, one to three times the limit, or more than three times
A total of 0–3 with negative serial troponins is low risk (about 1–2% major adverse cardiac events at 6 weeks): discharge with outpatient follow-up, without routine pre-discharge stress testing. Scores of 4–6 warrant observation and further testing, and ≥7 calls for an early invasive strategy.
Common noncardiac mimics
| Mimic | Distinguishing features | Confirm or treat |
|---|---|---|
| Costochondritis | Sharp, localized pain reproduced by pressing the 2nd–5th costochondral junctions (Tietze syndrome adds swelling, usually 2nd–3rd) | ECG still required; NSAIDs and reassurance |
| Herpes zoster | Unilateral, burning, band-like dermatomal pain that can precede vesicles by days | Antivirals within 72 hours of the rash; later if new lesions are still forming, or in older, immunocompromised or severe cases |
| GERD | Burning retrosternal pain after meals or lying down, sour taste, antacid relief | PPI trial after cardiac causes are excluded |
| Distal esophageal spasm | Squeezing pain, dysphagia to solids and liquids, triggered by hot or cold drinks, relieved by nitroglycerin | Manometry; corkscrew esophagus on barium study |
| Pericarditis | Sharp pleuritic pain, better sitting forward, worse supine; friction rub; diffuse concave ST elevation with PR depression (PR elevation in aVR) | Echo for effusion; NSAID or aspirin plus colchicine |
| Biliary colic | Steady epigastric or RUQ pain 30 minutes to hours after a fatty meal, radiating to the right scapula | RUQ ultrasound; still obtain an ECG |
| Panic attack | Abrupt surge peaking within about 10 minutes; palpitations, dyspnea, tremor, perioral tingling, fear of dying | Diagnosis of exclusion |
Traps. Reproducible chest wall tenderness is reassuring but does not exclude ACS. Relief with nitroglycerin does not separate angina from esophageal spasm, because nitrates relax both vascular and esophageal smooth muscle. Pericarditis lacks the reciprocal ST depression and Q waves of STEMI. Inferior MI can present as epigastric pain. Panic disorder is diagnosed only after ACS, PE, arrhythmia, hyperthyroidism and stimulant use are excluded.
Choosing a stress test
Who benefits. Noninvasive testing adds the most at intermediate pretest probability; at very low probability most positive results are false, and at high probability a negative result cannot exclude disease. Classic angina has three features — substernal discomfort, provoked by exertion or emotional stress, relieved by rest or nitroglycerin: all three are typical, two atypical, and one or none noncardiac, although current US guidance prefers the terms cardiac, possibly cardiac and noncardiac.
- Can exercise, interpretable ECGExercise treadmill ECG first-line.
- Can exercise, ECG not interpretableBaseline ST depression ≥1 mm, LVH with repolarization change, digoxin or WPW → exercise echocardiography or exercise nuclear perfusion imaging.
- LBBB or ventricular pacingVasodilator (regadenoson or adenosine) nuclear perfusion imaging, even if the patient can exercise.
- Cannot exerciseDobutamine stress echocardiography or vasodilator nuclear perfusion imaging.
Exercise ECG. The target is ≥85% of the age-predicted maximum heart rate (220 − age). A positive test is ≥1 mm of horizontal or downsloping ST depression; upsloping depression is not diagnostic. Beta-blockers, verapamil and diltiazem blunt the heart-rate response and are often held 24–48 hours when the goal is diagnosis. When the resting ECG is uninterpretable, exercise is still preferred to drugs because exercise capacity itself carries prognostic information.
Why LBBB needs a vasodilator. With LBBB or a paced rhythm, the ST segment cannot be read, and the tachycardia of exercise or dobutamine produces false-positive septal perfusion defects; vasodilator imaging avoids the tachycardia.
| Feature | Vasodilator (regadenoson, adenosine) | Dobutamine |
|---|---|---|
| Mechanism | A2A-mediated coronary hyperemia creates flow heterogeneity | β1 agonist raises heart rate and contractility |
| Imaging and ischemia sign | Nuclear perfusion; perfusion defect | Echocardiography; new wall-motion abnormality |
| Avoid in | Active bronchospasm, 2nd- or 3rd-degree AV block or sick sinus without a pacemaker, hypotension | Significant tachyarrhythmias, severe hypertension, LVOT obstruction |
| Preparation and reversal | Hold caffeine and other methylxanthines ≥12 hours; reverse with aminophylline | Reverse with a short-acting beta-blocker |
Interpreting results and anatomic testing
High-risk findings. Refer for coronary angiography when a stress test shows any of the following:
- ≥2 mm ST depression, especially at a low workload or persisting into recovery
- ST elevation in leads without Q waves, or sustained ventricular tachycardia
- A fall in systolic BP during exercise, which signals extensive ischemia (often multivessel or left main disease)
- A large or multiple-territory perfusion defect (≥10% of the myocardium) or transient ischemic dilation of the LV
- A Duke treadmill score ≤ −11
Duke treadmill score. Exercise minutes − 5 × maximal ST deviation (mm) − 4 × angina index (0 none, 1 nonlimiting, 2 test-limiting); ≥ +5 is low risk and ≤ −11 is high risk.
Coronary CT angiography. Best for low-to-intermediate-risk patients without known CAD, because its high negative predictive value rules out obstructive disease. It needs a slow, regular rhythm and iodinated contrast (caution in CKD or contrast allergy), and heavy calcification degrades the images.
Coronary artery calcium score. A noncontrast CT that refines risk in low-risk or asymptomatic patients; a score of 0 predicts very low near-term cardiovascular risk.
When not to stress test
Contraindications. Do not stress-test ongoing or high-risk ACS (MI within 2 days, a rising troponin, rest pain), symptomatic severe aortic stenosis, uncontrolled arrhythmias, decompensated heart failure, acute PE, acute myocarditis or pericarditis, active endocarditis, or acute aortic dissection.
Rest pain with a rising troponin is ACS and is managed as such, not tested. Exertional syncope or angina with a harsh late-peaking murmur at the right upper sternal border radiating to the carotids and a soft S2 needs an echocardiogram before anyone puts the patient on a treadmill.