Acute Chest Pain: A Detailed Differential Diagnosis Approach

Introduction

Chest pain is a frequently encountered complaint in healthcare settings, presenting a significant diagnostic challenge due to its wide range of potential causes, from benign conditions to life-threatening emergencies. Establishing an accurate differential diagnosis for acute chest pain is paramount, requiring a systematic approach to rapidly identify and rule out serious pathologies. A clinician’s primary focus must be on excluding critical conditions before considering more benign etiologies. Understanding the characteristics of chest pain, including visceral and somatic pain, is crucial in guiding the diagnostic process. Visceral pain, often described as dull, deep, pressure-like, or squeezing, can be referred to other locations due to shared nerve pathways. For instance, ischemic cardiac pain may radiate to the shoulder, jaw, or arm. This article aims to provide a comprehensive overview of the differential diagnosis of acute chest pain, emphasizing the importance of a thorough evaluation and the role of an interprofessional team in patient care.

Understanding the Etiology of Chest Pain

To effectively approach chest pain, it’s essential to differentiate between visceral and somatic pain, as their characteristics and potential origins differ significantly. Visceral pain typically arises from internal organs and is often characterized by a poorly localized, vague sensation. Patients may struggle to pinpoint the pain to a specific point, often gesturing to a broader area when asked to localize it. Descriptors commonly associated with visceral pain include dull, deep, pressure, and squeezing. A key feature of visceral pain is its potential to radiate or be referred to distant sites. This referral pattern occurs because visceral sensory nerves converge with somatic nerve fibers as they enter the spinal cord. A classic example is ischemic heart pain, which can manifest in locations such as the left or right shoulder, jaw, or left arm. Furthermore, visceral pain may be accompanied by autonomic symptoms like nausea and vomiting. Diaphragmatic irritation, another form of visceral pain, can also be referred to the shoulders.

In contrast, somatic pain originates from the skin, muscles, bones, and joints. It is generally more localized and specific than visceral pain. Patients experiencing somatic pain are usually able to identify the precise location of their discomfort with a single finger. Somatic pain is also less likely to radiate to other body regions. Common descriptors for somatic pain include sharp, stabbing, and poking. Recognizing these distinct characteristics of visceral and somatic pain is a crucial first step in developing an effective differential diagnosis for acute chest pain.

Epidemiology of Chest Pain in the Emergency Department

Chest pain is a prevalent complaint in emergency departments (EDs), ranking as the second most common reason for visits, accounting for approximately 5% of all ED presentations. When evaluating patients presenting with chest pain, healthcare providers must maintain a high index of suspicion for life-threatening conditions. A study by Fruergaard et al. provides valuable insights into the prevalence of various causes of chest pain in the ED setting. The study highlighted the following approximate percentages of life-threatening conditions among patients presenting to the ED with chest pain:

• Acute Coronary Syndrome (ACS): 31%
• Pulmonary Embolism (PE): 2%
• Pneumothorax (PTX): Prevalence unreported in this specific study, but clinically significant.
• Pericardial Tamponade: Prevalence unreported, but pericarditis in general was around 4%.
• Aortic Dissection: 1%
• Esophageal Perforation: Prevalence unreported, but a critical emergency.

In addition to these life-threatening etiologies, other common, though generally less immediately critical, causes of chest pain encountered in the ED include:

• Gastrointestinal Reflux Disease (GERD): 30%
• Musculoskeletal Causes: 28%
• Pneumonia/Pleuritis: 2%
• Herpes Zoster: 0.5%
• Pericarditis: Prevalence unreported, but part of the overall 4% pericardial disease.

These epidemiological data underscore the importance of a comprehensive and systematic approach to chest pain evaluation in the emergency department, prioritizing the rapid identification and exclusion of potentially fatal conditions while also considering the more common, less critical causes.

History and Physical Examination: Key to Unlocking the Diagnosis

A thorough history and physical examination are fundamental to the evaluation of chest pain, often providing critical clues to the underlying diagnosis.

History

Similar to any medical workup, the assessment of chest pain begins with obtaining a detailed patient history. It is essential to gain a comprehensive understanding of the patient’s complaint by asking specific and targeted questions:

• Onset: Determine when the pain started and, importantly, what the patient was doing at the time of onset. Was the pain triggered by exertion, or did it occur at rest? Exertional pain is more suggestive of cardiac ischemia, while pain at rest can also be cardiac but may indicate other conditions.
• Location: Ask the patient to pinpoint the location of the pain. Can they localize it with one finger, indicating a more somatic origin, or is it diffuse and widespread, suggesting visceral pain?
• Duration: Ascertain how long the pain episode lasts. The duration can help differentiate between acute and chronic conditions and may provide clues to the etiology.
• Character: Encourage the patient to describe the pain in their own words. Is it sharp, dull, pressure-like, burning, or stabbing? The character of the pain can be highly informative.
• Aggravating/Alleviating Factors: It is crucial to identify factors that worsen or relieve the pain. Is there an exertional component? Is it associated with eating, breathing, or specific body positions? Inquire about new workout routines, sports activities, or lifting heavy objects, which may suggest musculoskeletal causes. Also, ask about any medications the patient has tried and their effect on the pain.
• Radiation: Determine if the pain radiates to other areas, such as the arm, shoulder, jaw, or back. Radiation patterns can be highly suggestive of certain conditions, particularly visceral pain.
• Timing: Explore the frequency and pattern of pain episodes. How often does the pain occur? How long does each episode last? Are there periods of remission?

In addition to pain characteristics, inquire about associated symptoms, which can further narrow the differential diagnosis:

• Shortness of breath (dyspnea): May suggest cardiac, pulmonary, or anxiety-related causes.
• Nausea and vomiting: Often associated with visceral pain, including cardiac ischemia and gastrointestinal issues.
• Fever: Suggests infection, such as pneumonia or pleuritis.
• Diaphoresis (sweating): A common autonomic response in ACS and other serious conditions.
• Cough: May indicate pulmonary pathology like pneumonia, bronchitis, or pulmonary embolism.
• Dyspepsia (indigestion): Can be associated with GERD but also ACS, highlighting the importance of not solely attributing chest pain to gastrointestinal causes without excluding cardiac issues.
• Edema (swelling): May suggest heart failure or other systemic conditions.
• Calf pain or swelling: Raises suspicion for deep vein thrombosis (DVT) and potential pulmonary embolism.
• Recent illness: Recent upper respiratory infection (URI) may predispose to pneumonia or pleuritis.

Furthermore, it is essential to evaluate for risk factors that increase the likelihood of specific serious conditions:

• ACS Risk Factors: Prior myocardial infarction (MI), family history of cardiac disease, smoking, hypertension (HTN), hyperlipidemia (HLD), and diabetes mellitus.
• Pulmonary Embolism (PE) Risk Factors: Prior DVT or PE, hormone use (including oral contraceptives), recent surgery, cancer, or prolonged periods of immobility.
• Recent Gastrointestinal (GI) Procedures: Procedures like endoscopy can increase the risk of esophageal perforation.
• Drug Abuse: Cocaine and methamphetamine use are known to induce coronary artery vasospasm and myocardial infarction.

A thorough review of the patient’s medical history is crucial, including pre-existing cardiac conditions, coagulopathies, and kidney disease. Inquire about family history, particularly cardiac disease, and social history, including drug and tobacco use.

Once life-threatening causes have been carefully considered and initially assessed, it is appropriate to explore other potential etiologies. Pneumonia should be considered in patients presenting with productive cough and/or recent URI. Gastroesophageal reflux disease (GERD) is a very common cause of chest pain, so inquire about reflux symptoms such as heartburn and regurgitation. New exercise routines or recent trauma may point towards a musculoskeletal origin of the pain.

Physical Examination

The physical examination in patients with chest pain should be comprehensive and focus on identifying signs suggestive of serious underlying conditions. Key components include:

• Vital Signs: Obtain a full set of vital signs, including blood pressure (BP) measurements in both arms to assess for discrepancies suggestive of aortic dissection.
• General Appearance: Observe the patient’s overall appearance, noting any signs of diaphoresis, pallor, or distress.
• Skin Exam: Perform a thorough skin exam, looking for vesicular rash suggestive of herpes zoster (shingles), which can cause dermatomal chest pain.
• Neck Exam: Examine the neck for jugular venous distension (JVD), which can be a sign of heart failure or pericardial tamponade. Assess for Kussmaul’s sign (JVD worsening with inspiration), further supporting tamponade or constrictive pericarditis.
• Chest Palpation: Palpate the chest wall to assess for reproducible pain, which may indicate musculoskeletal etiology. Check for crepitus, which can suggest subcutaneous air from pneumothorax or esophageal perforation.
• Heart Auscultation: Perform a detailed heart exam, listening for murmurs, gallops, or pericardial friction rubs.
• Lung Auscultation: Auscultate the lungs to assess for breath sounds, wheezes, crackles, or diminished breath sounds suggestive of pneumonia, pneumothorax, or pulmonary embolism.
• Abdominal Exam: Perform an abdominal exam to rule out abdominal causes of referred chest pain, such as cholecystitis or peptic ulcer disease.
• Extremities Exam: Examine the extremities for unilateral swelling, calf tenderness, or edema, which may indicate DVT. Assess peripheral pulses for symmetry and equality, noting any discrepancies that could suggest aortic dissection or peripheral artery disease.

Evaluation Strategies for Acute Chest Pain

In evaluating acute chest pain, a tiered approach is essential, starting with investigations to rapidly rule out life-threatening conditions. Many healthcare facilities have established protocols for chest pain evaluation. At a minimum, the following investigations should be considered:

Electrocardiogram (ECG)

An ECG should be obtained promptly, ideally within the first 10 minutes of arrival, and serial ECGs should be considered to detect evolving changes. ECG is crucial for identifying ST-elevation myocardial infarction (STEMI) and other ischemic changes, as well as arrhythmias.

Chest X-Ray

A chest x-ray is a valuable initial imaging modality. It can help identify pneumothorax, pneumonia, pleural effusion, and mediastinal widening suggestive of aortic dissection or esophageal perforation.

Laboratory Investigations

Initial blood work should include:

• Complete Blood Count (CBC): To assess for infection (elevated white blood cell count) or anemia.
• Basic Metabolic Panel (BMP): To evaluate electrolytes, renal function, and glucose levels.
• Troponin Levels: Cardiac troponins are highly sensitive and specific markers for myocardial injury. Serial troponin levels, typically drawn 4 hours apart, are essential to rule out acute myocardial infarction.
• Lipase: May be considered if pancreatitis is suspected as a cause of referred chest pain.

Computed Tomography Pulmonary Angiography (CTPA)

CTPA is the gold standard for diagnosing pulmonary embolism. It should be performed if PE is suspected based on risk factors, clinical presentation, or unexplained hypoxia. Ventilation-perfusion (VQ) scans may be considered if CTPA is contraindicated, such as in patients with severe contrast allergy or renal insufficiency, although CTPA is generally preferred due to its higher accuracy and ability to identify alternative diagnoses.

Bedside Ultrasound (US)

Bedside ultrasound is a rapid and non-invasive tool that can be used to assess for pericardial effusion and tamponade. It is particularly useful in hemodynamically unstable patients where immediate assessment is critical. Ultrasound can also aid in evaluating for pneumothorax and pleural effusion.

Management and Treatment Based on Differential Diagnosis

The management of acute chest pain is dictated by the underlying diagnosis. Prompt and appropriate treatment is crucial, especially for life-threatening conditions.

Acute Coronary Syndrome (ACS) Management

The comprehensive management of ACS is extensive and beyond the scope of this article. However, initial critical steps in the ED include:

• Cardiac Monitoring: Continuous ECG monitoring is essential.
• Intravenous Access (IV): Establish IV access for medication administration.
• Aspirin Administration: Administer 162 mg to 325 mg of chewable aspirin immediately, unless contraindicated.
• Antiplatelet Therapy: Consider clopidogrel or ticagrelor in addition to aspirin, unless urgent bypass surgery is anticipated.
• Pain Management: Address pain with appropriate analgesia, such as morphine or fentanyl.
• Oxygen Therapy: Administer oxygen if the patient is hypoxic.
• Nitroglycerin: Nitroglycerin can be beneficial in relieving ischemic chest pain and reducing preload and afterload. Aim for a 10% reduction in mean arterial pressure (MAP) in normotensive patients and a 30% reduction in hypertensive patients. Avoid nitroglycerin in hypotensive patients and those with inferior ST-elevation myocardial infarction (inferior STEMI) due to potential right ventricular involvement.
• Reperfusion Therapy: For patients with ST-elevation myocardial infarction (STEMI), immediate reperfusion therapy is paramount. Percutaneous coronary intervention (PCI) is the preferred method and should be initiated within 90 minutes of arrival at a PCI-capable center or within 120 minutes if transfer to another facility is required. If PCI is not feasible within these timeframes, fibrinolytic therapy (thrombolytics) should be initiated within 30 minutes of arrival.
• Management of NSTEMI and Unstable Angina: Patients with non-ST elevation myocardial infarction (NSTEMI) and unstable angina require admission to the hospital for cardiology consultation and further evaluation, including consideration for angiography.
• Stable Angina Management: Patients with stable angina may be considered for outpatient workup and management, but careful risk stratification is necessary.
• Elderly and Comorbid Patients: Elderly patients and those with significant comorbidities often warrant admission for observation and further cardiac evaluation even if initial workup is not definitively diagnostic.

Pulmonary Embolism (PE) Management

• Anticoagulation: Initiate anticoagulation therapy promptly in patients with confirmed or suspected PE. Options include heparin, low molecular weight heparin (LMWH), fondaparinux, or direct oral anticoagulants (DOACs) depending on the clinical situation and patient factors.
• Thrombolysis: In hemodynamically unstable patients with massive PE, thrombolytic therapy (systemic or catheter-directed) may be life-saving.
• CTPA Confirmation: CT pulmonary angiography (CTPA) is the definitive diagnostic test for PE. VQ scan can be an alternative when CTPA is contraindicated, but it is less sensitive and specific, particularly in patients with underlying lung disease.

Pneumothorax (PTX) Management

• Chest Tube Decompression: Tension pneumothorax is a life-threatening emergency requiring immediate decompression, typically with needle thoracostomy followed by chest tube placement. Smaller, stable pneumothoraces may be managed with observation or aspiration in some cases, but chest tube drainage is often necessary, especially for larger pneumothoraces or symptomatic patients.

Pericardial Tamponade Management

• Pericardiocentesis: Pericardial tamponade requires urgent drainage of the pericardial fluid. Needle pericardiocentesis is a temporizing measure, and a pericardial window (surgical drainage) may be required for definitive management and to prevent recurrence.
• Fluid Bolus: In hypotensive patients with tamponade, a fluid bolus may temporarily improve hemodynamics while preparing for drainage.
• Bedside Ultrasound Diagnosis: Bedside ultrasound is invaluable for rapid diagnosis of pericardial tamponade.

Aortic Dissection Management

• Blood Pressure Control: Rapid and aggressive blood pressure reduction is critical in aortic dissection to reduce shear stress on the aortic wall. Aim for a systolic blood pressure between 100 mmHg and 120 mmHg initially. Beta-blockers are the first-line agents to reduce heart rate and blood pressure, and to decrease the force of ventricular contraction (negative inotropy).
• Surgical Consultation: Immediate consultation with cardiothoracic surgery is essential as surgical repair is often required, especially for type A aortic dissections (involving the ascending aorta). Type B dissections (descending aorta) may be managed medically in certain stable cases.
• CT Angiography Diagnosis: CT angiography is the preferred imaging modality for diagnosing aortic dissection.
• Large-Bore IV Access: Establish two large-bore IV lines for fluid and medication administration.

Esophageal Perforation Management

• Surgical Consultation: Esophageal perforation is a surgical emergency requiring immediate surgical consultation.
• Contrast Esophagram Diagnosis: A contrast esophagram is the best confirmatory test for esophageal perforation.
• Chest X-Ray Findings: A left pleural effusion on chest x-ray may be a suggestive finding of esophageal rupture.

Gastroesophageal Reflux Disease (GERD) Management

• GI Cocktail: A “GI cocktail” consisting of viscous lidocaine mixed with Maalox or Mylanta can be administered for symptomatic relief. While therapeutic, it is not diagnostic, and it is crucial to rule out ACS before attributing chest pain solely to GERD, as ACS can also present with dyspeptic symptoms and may even respond to GI cocktail.
• Proton Pump Inhibitors (PPIs) or H2 Blockers: Long-term management of GERD typically involves proton pump inhibitors (PPIs) or H2 receptor antagonists to reduce gastric acid production.

Differential Diagnosis

The differential diagnosis for acute chest pain is broad and includes a wide spectrum of conditions. Key considerations include:

• Acute Coronary Syndrome (ACS)
• Aortic Dissection
• Pulmonary Embolism (PE)
• Pneumothorax (PTX)
• Pericardial Tamponade
• Esophageal Perforation/Rupture
• Gastroesophageal Reflux Disease (GERD)
• Musculoskeletal Chest Pain
• Pneumonia/Pleuritis
• Herpes Zoster (Shingles)
• Cervical Radiculopathy
• Esophageal Spasm

Pearls and Clinical Considerations

• Aortic Dissection and Stroke: Be aware that aortic dissection can present with neurological symptoms, including stroke, due to involvement of arteries supplying the brain. Consider aortic dissection in the differential diagnosis of stroke, particularly in patients with chest pain or other suggestive features.
• Atypical MI Presentations: Younger patients and those without traditional risk factors can still experience myocardial infarction. Maintain a high index of suspicion even in lower-risk individuals.
• Diabetes and Elderly Patients: Patients with diabetes and elderly individuals may have atypical presentations of ACS due to nerve damage (neuropathy), which can alter pain perception. They may present with less typical chest pain or even pain equivalents like shortness of breath, fatigue, or nausea.

Enhancing Interprofessional Team Outcomes in Chest Pain Management

Effective management of chest pain requires a collaborative interprofessional team approach. This team typically includes nurse practitioners, primary care providers, internists, emergency department physicians, cardiologists, and surgeons. A thorough medical history, obtained by any member of the team, often provides crucial diagnostic clues. The key is to prioritize the identification and exclusion of life-threatening conditions such as acute MI and aortic dissection. When the etiology of chest pain remains uncertain after initial evaluation, referral to a specialist, such as a cardiologist or pulmonologist, is recommended for further investigation and management. Patient outcomes in chest pain depend significantly on the underlying cause and the timeliness and appropriateness of interventions. Effective communication, shared decision-making, and coordinated care among the interprofessional team are essential to optimize patient outcomes in chest pain management.

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