Is it necessary to obtain an electrocardiogram (EKG) for a patient who experienced an episode of tachycardia?

Obtaining an ECG in Patients with Tachycardia

A 12-lead ECG is absolutely necessary for all patients who have experienced an episode of tachycardia, even if symptoms have resolved. 1, 2

Rationale for ECG Documentation

The ACC/AHA/ESC guidelines clearly state that whenever possible, a 12-lead ECG should be taken during tachycardia, and at minimum, patients with a history of sustained arrhythmia should always be encouraged to have at least one 12-lead ECG taken during the arrhythmia 1. This is crucial for several reasons:

• Proper diagnosis of the tachycardia mechanism requires ECG documentation
• Distinguishing between supraventricular and ventricular origins is essential for treatment decisions
• Even in the absence of structural heart disease, tachycardia can indicate serious underlying conditions

Diagnostic Value of ECG

The ECG provides critical information that guides management:

• QRS duration: Narrow (<120 ms) suggests supraventricular origin; wide (≥120 ms) may indicate ventricular tachycardia or SVT with aberrancy 1
• P wave morphology and relationship to QRS: Helps differentiate between AVNRT, AVRT, and atrial tachycardia 1
• Regularity of rhythm: Regular vs. irregular patterns suggest different mechanisms 1
• Evidence of pre-excitation: Delta waves may indicate accessory pathways 3

Risk Assessment

Without an ECG, you cannot:

1. Rule out life-threatening arrhythmias
2. Determine if the patient has pre-excitation (WPW syndrome)
3. Identify structural heart disease markers
4. Assess for prolonged QT or other conduction abnormalities

Management Implications

The ACC/AHA/ESC guidelines emphasize that management depends on proper ECG documentation 1:

• Without ECG documentation: Treatment options are limited to empiric therapy, which may be inappropriate or potentially harmful
• With ECG documentation: Specific therapy can be targeted to the underlying mechanism

Pitfalls to Avoid

1. Relying on symptoms alone: Patients who are symptomatic during acquisition of a normal or nonspecific ECG have similar rates of adverse cardiovascular events as those without symptoms 4

2. Assuming benign etiology: Even patients with normal physical examinations can have serious underlying arrhythmias

3. Delaying ECG acquisition: The guidelines state that a 12-lead ECG should be obtained immediately to confirm the QRS morphology 5

4. Missing pre-excitation: Patients with pre-excitation and paroxysmal palpitations should be referred for electrophysiological evaluation due to risk of sudden death 1

When ECG is Insufficient

If symptoms are infrequent (fewer than two episodes per month), consider:

• Event recorder or loop recorder for intermittent symptoms 1
• Implantable loop recorder for rare but severe symptoms 1
• Holter monitoring for frequent symptoms 1

Conclusion

Not obtaining an ECG from a patient with tachycardia represents a significant gap in care. The ACC/AHA/ESC guidelines clearly indicate that ECG documentation is essential for proper diagnosis, risk stratification, and management of patients with tachycardia 1. The Praxis Medical Insights also emphasizes that continuous cardiac monitoring is essential to detect intermittent arrhythmias not captured on a single ECG 2.