ECG Differential Diagnosis

When considering a diagnosis based on an ECG (electrocardiogram), it's crucial to approach the interpretation systematically to cover a wide range of potential cardiac issues. Here's a structured differential diagnosis:

• Single Most Likely Diagnosis
  • Normal Variant: Many ECGs are interpreted as normal variants, especially in asymptomatic individuals. A normal ECG does not necessarily rule out cardiac disease but indicates no significant abnormality at the time of the recording.
• Other Likely Diagnoses
  • Hypertension: Indicated by left ventricular hypertrophy (LVH) patterns, which can be a common finding in patients with chronic high blood pressure.
  • Ischemic Heart Disease: ST-segment changes, Q-waves, or T-wave inversions may suggest myocardial ischemia or infarction.
  • Atrial Fibrillation: The most common sustained cardiac arrhythmia, characterized by an irregularly irregular rhythm.
• Do Not Miss Diagnoses
  • Acute Myocardial Infarction (MI): ST-elevation MI (STEMI) or non-ST elevation MI (NSTEMI) requires immediate recognition and intervention.
  • Pulmonary Embolism: While not always diagnostic, ECG changes such as the S1Q3T3 pattern or new right bundle branch block can suggest pulmonary embolism.
  • Cardiac Tamponade: Electrical alternans or low QRS voltage may indicate cardiac tamponade, a life-threatening condition.
• Rare Diagnoses
  • Brugada Syndrome: Characterized by specific ST-segment elevations in leads V1-V3, associated with an increased risk of sudden cardiac death.
  • Long QT Syndrome: Prolongation of the QT interval can predispose to torsades de pointes, a potentially fatal arrhythmia.
  • Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC): Epsilon waves in leads V1-V3 and right ventricular dilatation may suggest ARVC, a rare cause of sudden cardiac death.

Each of these diagnoses requires careful consideration of the ECG findings in the context of the patient's clinical presentation, medical history, and other diagnostic tests.