Differential Diagnosis of STEMI

Critical Life-Threatening Conditions to Rule Out Immediately

The American College of Cardiology and the European Society of Cardiology recommend identifying true STEMI requiring immediate reperfusion therapy, while simultaneously recognizing other potentially catastrophic causes including aortic dissection, massive pulmonary embolism, and acute pericarditis 1, 2

The European Society of Cardiology recommends that aortic dissection be excluded immediately, particularly when ST-depression >0.1 mV appears in eight or more leads with ST elevation in aVR and/or V1, especially with hemodynamic compromise 3, 4
Acute pericarditis presents with widespread ST elevation (typically concave upward) with PR depression, distinguishing it from the convex ST elevation and reciprocal changes seen in STEMI, according to the European Heart Journal 3, 1

The European Heart Journal recommends obtaining 12-lead ECG and interpreting for true STEMI criteria: ≥0.25 mV in men <40 years, ≥0.2 mV in men ≥40 years, or ≥0.15 mV in women in V2-V3; ≥0.1 mV in other leads at J point in two contiguous leads 3, 5
The European Society of Cardiology suggests adding posterior leads (V7-V9) if suspecting isolated posterior MI (ST depression in V1-V3 as dominant finding) 3, 4

Blood pressure differences between limbs suggest aortic dissection, according to Praxis Medical Insights 6
New systolic murmur may indicate mechanical complications or endocarditis, as stated by Praxis Medical Insights 6
Pericardial friction rub points toward pericarditis, according to the European Heart Journal 3

The European Heart Journal recommends obtaining high-sensitivity cardiac troponin at presentation and repeat per validated algorithm (0h/1h or 0h/2h protocol) 7, 5
The European Society of Cardiology advises not to delay reperfusion therapy waiting for troponin results if ECG shows STEMI 3

Praxis Medical Insights suggests identifying supply-demand mismatch precipitants: severe hypertension, tachyarrhythmias, severe anemia, hypotension, respiratory failure, or coronary spasm causing troponin elevation without acute atherothrombosis 6
Treatment focuses on correcting the underlying precipitating condition rather than immediate catheterization, according to Praxis Medical Insights 6

The European Heart Journal warns to never administer thrombolytics without confirming true STEMI, as focal myopericarditis patients risk catastrophic complications including hemorrhagic tamponade 3
Praxis Medical Insights advises not to dismiss tachycardia as excluding MI; sympathetic activation commonly causes tachycardia in acute MI and should heighten suspicion 5
The European Heart Journal states that normal ECG does not exclude MI; the ECG is seldom completely normal even early, but repeated recordings may be necessary 3
The European Society of Cardiology recommends considering left main/multivessel disease when ST depression appears in ≥8 leads with ST elevation in aVR, requiring immediate angiography regardless of troponin 4, 5

Patients with STEMI may present with tearing chest pain radiating to the back, which differs from the typical crushing substernal pain of MI, according to the European Society of Cardiology 8
Pain is typically sharp, positional (worse when supine, better leaning forward), and pleuritic in nature, as noted by the European Society of Cardiology 8
The American College of Cardiology recommends considering recent immobilization, surgery, or known hypercoagulable state as clinical context for massive pulmonary embolism 9
The European Society of Cardiology suggests that left ventricular hypertrophy can cause baseline ST elevation, particularly in precordial leads 8
Early repolarization shows J-point elevation with characteristic notching, typically in young patients, as described by the European Society of Cardiology 8
Left bundle branch block (new or presumed new) requires treatment as STEMI equivalent, according to the American Heart Association 8, 10

The American College of Cardiology recommends adding right-sided leads (V4R) if inferior STEMI to detect right ventricular involvement 8
The European Society of Cardiology suggests examining for signs of heart failure (rales, S3 gallop, jugular venous distension) 8
Serial troponins help distinguish Type 1 from Type 2 MI and assess infarct size, as noted by the American College of Cardiology and the American Heart Association 9, 10
Hemodynamic instability, cardiogenic shock, or mechanical complications mandate emergent catheterization, according to the European Society of Cardiology 8

The American College of Cardiology recommends against dismissing tachycardia as excluding MI—sympathetic activation commonly causes tachycardia in acute MI and should heighten suspicion 9
Atypical presentations (dyspnea, fatigue, syncope without chest pain) are common in women, elderly, and diabetic patients, as described by the European Society of Cardiology 8
Epigastric or interscapular pain may represent inferior or posterior MI rather than gastrointestinal pathology, according to the European Society of Cardiology 8