# Chest Pain Evaluation in the Outpatient Setting ## Overview Chest pain accounts for millions of primary care and urgent care visits annually. The primary clinical task is to rapidly identify life-threatening causes, particularly acute coronary syndrome, pulmonary embolism, aortic dissection, and tension pneumothorax, while avoiding unnecessary emergency referrals for low-risk presentations. Systematic risk stratification using validated tools is far more reliable than clinical intuition alone. ## Differential Diagnosis ### Cardiac Acute coronary syndrome encompasses unstable angina, NSTEMI, and STEMI. Stable angina pectoris presents as predictable exertional chest discomfort relieved by rest or nitroglycerin. Pericarditis produces sharp, pleuritic, positional pain (characteristically improved by leaning forward) with diffuse ST elevation and PR depression on ECG. Myocarditis often follows a viral prodrome and causes chest pain with troponin elevation and ECG changes. Aortic stenosis causes exertional chest pain, syncope, and dyspnea, with a systolic crescendo-decrescendo murmur on examination. ### Pulmonary Pulmonary embolism presents with pleuritic chest pain, dyspnea, and tachycardia in the setting of risk factors such as immobility, oral contraceptive use, malignancy, or recent surgery. Pneumothorax causes sudden pleuritic pain and dyspnea with absent breath sounds on the affected side. Pneumonia and pleuritis produce fever, cough, and pleuritic pain. ### Gastrointestinal GERD causes burning substernal pain that worsens when supine and after meals and can closely mimic angina. Esophageal spasm produces retrosternal squeezing that can be relieved by nitroglycerin, creating a diagnostic confound. Peptic ulcer disease, biliary colic, and pancreatitis should also be considered. ### Musculoskeletal Costochondritis, the most common cause of chest pain in primary care, produces reproducible tenderness at the costochondral junctions. Muscle strain is activity-related and reproducible with movement or palpation. Rib fracture causes point tenderness with a history of trauma or severe coughing. ### Other Anxiety and panic disorder often present with recurrent chest pain accompanied by hyperventilation, palpitations, and diaphoresis, but this remains a diagnosis of exclusion. Herpes zoster produces dermatomal burning pain that may precede the rash. Aortic dissection causes tearing pain radiating to the back, often with a blood pressure differential between arms, and constitutes an emergency. ## Risk Stratification for ACS ### History Features Features favoring a cardiac etiology include substernal pressure or heaviness, radiation to the jaw or left arm or both arms, exertional onset with relief at rest, and associated dyspnea, diaphoresis, or nausea. Traditional risk factors include age over 40, male sex, diabetes, smoking, hypertension, dyslipidemia, and family history of premature coronary disease. Features favoring a non-cardiac etiology include sharp or stabbing quality, reproducibility with palpation, positional variation, very brief duration (under 5 seconds) or very prolonged duration (hours to days) without other ACS features, and localization to a single point. However, no single feature reliably excludes ACS, and clinical gestalt must integrate the full picture. ### HEART Score (for ED/Urgent Care Settings) The HEART score assigns points for History (0 to 2), ECG findings (0 to 2), Age (0 to 2), Risk factors (0 to 2), and Troponin (0 to 2). A score of 0 to 3 indicates low risk with a MACE rate below 2%, supporting consideration of discharge with outpatient follow-up. A score of 4 to 6 indicates moderate risk warranting observation, serial troponins, and cardiology consultation. A score of 7 or above indicates high risk requiring admission and urgent cardiology evaluation. | HEART Score | Risk Level | 6-Week MACE Rate | Disposition | |-------------|-----------|-----------------|-------------| | 0-3 | Low | <2% | Consider discharge with outpatient follow-up | | 4-6 | Moderate | 12-16% | Observation, serial troponins, cardiology consult | | ≥7 | High | >50% | Admission, urgent cardiology evaluation | ### High-Sensitivity Troponin (hs-cTn) High-sensitivity troponin assays detect smaller amounts of myocardial injury than conventional assays, making them more sensitive but less specific for ACS. Elevations can occur in heart failure, CKD, pulmonary embolism, sepsis, and myocarditis. Rapid rule-out protocols using 0/1-hour or 0/3-hour algorithms have been validated. In outpatient settings, availability of these assays may be limited. ## ECG Interpretation for ACS STEMI is diagnosed by ST elevation of 1 mm or more in two contiguous leads (2 mm or more in V1 through V3), requiring catheterization lab activation. NSTEMI presents with ST depression, T-wave inversions, or dynamic ECG changes with a positive troponin. A new left bundle branch block in the context of chest pain should be treated as a STEMI equivalent, though this is debated. Wellens syndrome, characterized by deep symmetric T-wave inversions in V2 and V3, indicates critical LAD stenosis. The de Winter pattern shows upsloping ST depression with tall T-waves in precordial leads, representing an LAD occlusion variant. Comparison with a prior ECG, when available, is always valuable. ## Outpatient Disposition Decisions Immediate ED referral is indicated for STEMI on ECG, hemodynamic instability, ongoing ischemic symptoms, a high HEART score, positive troponin, or suspected aortic dissection or pulmonary embolism. Urgent outpatient follow-up within 24 to 72 hours is appropriate for patients with a low HEART score, resolved symptoms, normal ECG, negative troponin, and reliable follow-up. Routine follow-up is sufficient for clearly non-cardiac etiologies such as musculoskeletal or GERD-related chest pain, with treatment directed at the presumptive cause. ## Outpatient Cardiac Testing ### Stress Testing Exercise treadmill testing is first-line for patients who can exercise and have an interpretable baseline ECG (no LBBB, LVH with repolarization changes, digoxin effect, or pre-excitation). Stress echocardiography, performed with exercise or dobutamine, assesses regional wall motion abnormalities. Nuclear stress testing with myocardial perfusion imaging, using pharmacologic stress (regadenoson) or exercise, is appropriate for patients who cannot exercise or have an uninterpretable ECG. Stress cardiac MRI is an emerging modality with excellent sensitivity and specificity. ### Coronary CT Angiography (CCTA) CCTA offers a negative predictive value exceeding 99%, making it excellent for ruling out coronary artery disease. The PROMISE and SCOT-HEART trials demonstrated that CCTA is comparable to functional testing for clinical outcomes. It is particularly useful for low-to-intermediate risk patients. Limitations include radiation exposure, contrast requirements, and reduced accuracy when extensive coronary calcification is present. ### Appropriateness Testing should be avoided in very low-risk patients (pretest probability below 5%), where false positives cause more harm than the disease likelihood warrants. Very high-risk patients should proceed directly to catheterization. Testing is most informative at intermediate pretest probability. ## Non-Cardiac Chest Pain Management Costochondritis is managed with reassurance, NSAIDs, and topical analgesics; it is self-limited over weeks to months. GERD responds to a two-to-four-week PPI trial, with symptom resolution effectively confirming the diagnosis. Anxiety and panic disorder should be screened for with GAD-7, with reassurance provided only after appropriate cardiac workup. Musculoskeletal causes respond to rest, NSAIDs, and physical therapy. A clinical triage algorithm for outpatient chest pain evaluation beginning with initial assessment (vital signs, history, physical exam), then branching based on red flags for immediate ED referral versus outpatient workup. Show the HEART score calculation pathway for moderate-risk patients, and the appropriate cardiac testing options (ETT, stress echo, nuclear, CCTA) based on patient characteristics and exercise ability. An ECG pattern recognition guide showing side-by-side examples of STEMI in different vascular territories (anterior, inferior, lateral), NSTEMI with ST depression, Wellens syndrome T-wave patterns (type A biphasic and type B deep symmetric inversions), and de Winter T-waves. Label each pattern with the culprit artery and clinical significance. A differential diagnosis infographic for chest pain organized by organ system (cardiac, pulmonary, GI, musculoskeletal, psychiatric) with key distinguishing features, associated symptoms, and first-line diagnostic tests for each condition. Use color-coded sections with icons representing each organ system. ## Clinical Pearls Chest wall tenderness does not exclude ACS; up to 15% of patients with acute coronary syndrome have reproducible chest wall tenderness. GERD and esophageal spasm can both be relieved by nitroglycerin, making the "nitroglycerin response test" unreliable for confirming a cardiac etiology. The HEART score is validated for ED settings and should be used to support disposition decisions objectively rather than relying on gestalt alone. High-sensitivity troponin increases diagnostic sensitivity but also detects non-ACS myocardial injury, requiring interpretation within the clinical context. Young women presenting with chest pain are at risk of delayed ACS diagnosis due to atypical presentations and provider bias. Coronary CT angiography is increasingly favored for low-to-intermediate risk patients because of its high negative predictive value. Panic disorder is a diagnosis of exclusion; an adequate cardiac workup must precede attributing chest pain to anxiety. Every patient discharged from an outpatient setting with chest pain should receive documented safety net instructions including specific return precautions. ## References - Amsterdam EA et al. 2014 AHA/ACC Guideline for Management of NSTE-ACS. Circulation. 2014 - Six AJ et al. The HEART Score for Chest Pain Patients at the Emergency Department. Neth Heart J. 2008 - Mahler SA et al. The HEART Pathway Randomized Trial. Circ Cardiovasc Qual Outcomes. 2015 - SCOT-HEART Investigators. CT Coronary Angiography in Patients with Stable Chest Pain. NEJM. 2018 - Douglas PS et al. PROMISE Trial: Functional vs. Anatomical Testing for CAD. NEJM. 2015 - Braunwald E. Unstable Angina and NSTEMI. In: Braunwald's Heart Disease. 12th ed.