No, SVT and Atrial Tachycardia Are Not the Same
Supraventricular tachycardia (SVT) is an umbrella term that includes atrial tachycardia (AT) as one of several specific subtypes, meaning AT is a type of SVT, but SVT encompasses multiple distinct arrhythmias beyond just AT. 1
Understanding the Terminology
SVT as the Broader Category
According to the ACC/AHA/HRS guidelines, SVT is defined as any tachycardia (heart rate >100 bpm at rest) where the mechanism involves tissue from the His bundle or above 1. This umbrella term specifically includes:
- Inappropriate sinus tachycardia 1
- Atrial tachycardia (focal, multifocal, and sinus node reentry) 1
- Macroreentrant atrial tachycardia (including typical atrial flutter) 1
- Junctional tachycardia 1
- Atrioventricular nodal reentrant tachycardia (AVNRT) 1
- Accessory pathway-mediated reentrant tachycardias (AVRT) 1
Atrial Tachycardia as a Specific Subtype
Atrial tachycardia represents just one category within the SVT spectrum 1. The ACC/AHA/HRS guidelines define AT as having three distinct forms:
- Focal AT: Arises from a localized atrial site with regular, organized atrial activity showing discrete P waves with isoelectric segments between them 1
- Sinus node reentry tachycardia: Microreentry from the sinus node complex with P-wave morphology indistinguishable from sinus rhythm 1
- Multifocal atrial tachycardia (MAT): Irregular SVT with ≥3 distinct P-wave morphologies at different rates 1
Clinical Implications of the Distinction
Why the Distinction Matters
The differentiation is clinically crucial because management strategies differ significantly based on the specific SVT mechanism 2, 3:
- AVNRT and AVRT respond well to vagal maneuvers and adenosine, with catheter ablation success rates exceeding 95% 2, 4
- Focal AT may require different ablation approaches targeting the specific atrial focus 1
- MAT typically requires treatment of underlying conditions (often pulmonary disease) rather than ablation 1
Paroxysmal SVT (PSVT) - Another Important Subset
The guidelines define PSVT as a clinical syndrome characterized by regular, rapid tachycardia with abrupt onset and termination 1. These features are most characteristic of AVNRT or AVRT, and less frequently AT 1. PSVT represents a subset of SVT, not a synonym for it 1.
Common Clinical Pitfall
The most critical error is using "SVT" and "atrial tachycardia" interchangeably in clinical documentation or treatment planning. 1 When a patient presents with a narrow-complex tachycardia, stating "SVT" without further specification provides insufficient information for optimal management 2, 3. The specific mechanism (AVNRT, AVRT, focal AT, etc.) should be identified through careful ECG analysis, comparison with sinus rhythm tracings, and response to interventions like adenosine 5, 2.
Practical Diagnostic Approach
When evaluating a patient with suspected SVT 1, 5:
- Examine P wave morphology: AT shows discrete P waves that differ from sinus P waves, while AVNRT often has P waves buried in or immediately after the QRS complex 1, 5
- Assess regularity: AT (except MAT) is regular, as are AVNRT and AVRT 1
- Check response to adenosine: AVNRT/AVRT typically terminate abruptly, while AT may show transient AV block revealing underlying atrial activity 5, 2
- Compare with baseline ECG: P wave morphology during tachycardia versus sinus rhythm helps identify the mechanism 5