Differential Diagnosis for ECG Interpretation
When considering an ECG for diagnosis, several conditions come into play. Here's a structured approach to differential diagnosis:
- Single Most Likely Diagnosis
- Normal Variant: Many ECGs are interpreted for individuals without cardiac symptoms or known heart disease. A normal variant, such as a benign early repolarization or a normal sinus rhythm with occasional premature beats, could be the most common finding.
- Other Likely Diagnoses
- Atrial Fibrillation: A common arrhythmia, especially in older adults, characterized by an irregularly irregular rhythm.
- Ventricular Hypertrophy: Indications of left or right ventricular hypertrophy are common in hypertensive patients or those with heart valve diseases.
- Myocardial Ischemia or Infarction: Signs of ischemia or previous myocardial infarction, such as Q-waves, ST-segment elevation, or depression, are significant findings.
- Do Not Miss Diagnoses
- Acute Myocardial Infarction (STEMI): ST-segment elevation indicative of an acute myocardial infarction requiring immediate intervention.
- Pulmonary Embolism: While not always diagnostic, certain ECG patterns (e.g., S1Q3T3 pattern, AF, or right bundle branch block) can suggest pulmonary embolism, a potentially life-threatening condition.
- Cardiac Tamponade: Low voltage QRS or electrical alternans can be indicative of 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, which can predispose to torsades de pointes and sudden cardiac death.
- Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC): Characterized by epsilon waves, T-wave inversion in the right precordial leads, and sometimes ventricular arrhythmias.
Each of these diagnoses has distinct ECG features and clinical implications. The interpretation must consider the patient's symptoms, medical history, and physical examination findings to accurately diagnose and manage the condition.