What is the differential diagnosis for Acute Coronary Syndrome (ACS) in a patient with a history of hypertension, atherosclerosis, and previous cardiovascular surgery presenting with symptoms suggestive of acute aortic dissection?

Differential Diagnosis for Acute Coronary Syndrome

When evaluating a patient presenting with symptoms suggestive of ACS, particularly one with hypertension, atherosclerosis, and prior cardiovascular surgery, aortic dissection must be immediately considered and excluded before initiating any anticoagulation or thrombolytic therapy, as these treatments can be catastrophic if dissection is present. 1, 2

Life-Threatening Conditions Requiring Immediate Exclusion

Aortic Dissection

• This is the most critical differential diagnosis because misdiagnosis can lead to fatal outcomes if thrombolytic therapy is administered 2, 3
• The typical patient is a male in his 60s with hypertension—identical to the ACS population 1, 2
• Pain characteristics differ: dissection pain is abrupt with maximum intensity at onset, whereas MI pain builds gradually 1, 2
• Proximal (Type A) dissections cause retrosternal pain (71% anterior chest pain), while distal dissections cause interscapular/back pain 1, 4
• Up to 20% present with syncope without typical pain 1, 2
• Check for pulse deficits, blood pressure differential between arms (>20 mmHg systolic), and new aortic regurgitation murmur 5, 4

Other Cardiovascular Emergencies

• Pulmonary embolism: presents with dyspnea, pleuritic chest pain, and hypoxia 1
• Acute aortic regurgitation without dissection: may cause heart failure symptoms and pulmonary edema 1
• Cardiac tamponade: can occur with Type A dissection or pericarditis, presenting with hypotension and syncope 1

Non-Ischemic Cardiovascular Causes

Pericarditis

• Pain changes with inspiration and position, unlike ACS 1
• Diffuse concave upward ST elevation and PR depression on ECG 1
• Pericardial friction rub present in only one-third of patients 1
• Small pericardial effusion detectable in 60% of cases on echocardiography 1
• Up to 50% have elevated troponin (termed perimyocarditis), which can confuse the diagnosis 1

Expanding Aortic Aneurysm

• Consider in patients with known atherosclerosis and hypertension 1, 5
• May present with chest, back, or abdominal pain depending on location 1

Noncardiovascular Causes

Musculoskeletal Pain

• Pain reproducible with palpation of chest wall 1, 6
• Pain varies with breathing or position 6
• These features make ACS less likely but do not exclude it 1

Gastrointestinal Causes

• Cholecystitis: right upper quadrant pain, may radiate to chest 1
• Esophageal spasm: can mimic cardiac pain but typically related to swallowing 1
• Gastroesophageal reflux: burning quality, worse when supine 1

Pulmonary Causes

• Pleurisy: sharp, pleuritic chest pain worsened by breathing 1
• Pneumothorax: sudden onset dyspnea with unilateral decreased breath sounds 1

Psychiatric Disorders

• Panic attacks and anxiety disorders can mimic ACS 1
• Consider only after excluding life-threatening causes 1

Critical Diagnostic Approach

Immediate Assessment

• Obtain 12-lead ECG within 10 minutes of presentation 1, 7
• Measure blood pressure in both arms to detect dissection 5, 4
• Assess for pulse deficits in all extremities 1, 4
• Auscultate for new diastolic murmur of aortic regurgitation 5, 4

Risk Stratification for Dissection

High-risk features requiring immediate imaging include: 4

• Marfan syndrome or connective tissue disorders
• Family history of aortic disease
• Known bicuspid aortic valve
• Recent aortic manipulation or cardiac surgery
• Known thoracic aortic aneurysm

Imaging Strategy

• If dissection suspected: CT angiography is the diagnostic test of choice (100% sensitivity) 5
• Transthoracic echocardiography has only 60-80% sensitivity for Type A dissection 1
• Transesophageal echocardiography has 98-100% sensitivity but may be dangerous in unstable patients 1

Common Pitfalls to Avoid

• Never administer thrombolytics or anticoagulation until dissection is excluded in patients with risk factors 2, 3
• Do not rely on "classic tearing pain" description—only 51-64% describe pain as sharp or stabbing 4
• Normal chest X-ray does not exclude dissection (mediastinal widening present in only 62.6% of Type A dissections) 4
• D-dimer >0.5 µg/mL has high sensitivity for dissection but should not be used alone to rule it out 2, 4
• Atypical presentations (epigastric pain, isolated dyspnea) are more common in elderly patients, women, and those with diabetes 1
• Up to 6.4% of dissections present without pain, particularly in older patients and those with Marfan syndrome 4