Atrial Tachycardia

Aka: Atrial Tachycardia, Focal Atrial Tachycardia, Multifocal Atrial Tachycardia

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II. Definitions

  1. Atrial Tachycardia
    1. Form of Paroxysmal Supraventricular Tachycardia (10% of cases) with increased automaticity

III. Epidemiology

  1. Least common Supraventricular Tachycardia (10% of cases, less common than AVNRT, AVRT)
  2. Most often in otherwise healthy young adults

IV. Pathophysiology

  1. Abnormal single focus of atrial automaticity (outside the SA Node) or microreentry within the atria
  2. Unlike AVNRT and AVRT, no accessory pathway is involved

V. Findings: Electrocardiogram

  1. Heart Rate 130 to 180 (up to 250 bpm)
    1. Contrast with Atrial Flutter (250 to 350 bpm)
  2. At least one atrial beat for every ventricular beat
    1. However atrial beats may exceed ventricular beats (e.g. 1:1 or 1:4 AV conduction)
    2. Similar to Atrial Flutter, but Atrial Tachycardia rates are slower (<250 bpm)
  3. May occur in repetitive short bursts of Atrial Tachycardia
  4. P Wave morphology varies by atrial focus and is best visualized in leads V1 and II
  5. PR Interval is normal
  6. RP Interval is longer than PR Interval
  7. When due to increased automaticity
    1. Rate typically ramps up over a 5 to 10 second period before reaching a more constant Tachycardia
    2. In contrast, microreentry mechanisms start and stop abruptly
    3. Contrast with Sinus Tachycardia which ramps up more slowly and responds to physiologic measures (e.g. IV fluids)

VI. Types

  1. Atrial Tachycardia
    1. Focal
    2. Microreentry
  2. Multifocal Atrial Tachycardia
    1. Irregular narrow complex rhythm with 3 or more different P Wave morphologies

VII. Causes: Multifocal Atrial Tachycardia

  1. Causes: Enlarged atrium
    1. Chronic lung disease
    2. Congestive Heart Failure
  2. Causes: Other
    1. Acid-base disturbance
    2. Electrolyte abnormalities
      1. Hypokalemia
      2. Hypomagnesemia

VIII. Management: Focal Atrial Tachycardia

  1. Catheter Ablation Indications
    1. Recurrent Focal Atrial Tachycardia
    2. Secondary Cardiomyopathy due to Atrial Tachycardia
  2. Medical Management
    1. Beta Blocker (e.g. Metoprolol)
    2. Nondihydropyridine Calcium Channel Blocker (e.g. Diltiazem)
      1. Contraindicated in Congestive Heart Failure
    3. Antiarrhythmics (Propafenone, Flecainide)
      1. Indicated in ischemic or structural heart disease

IX. References

  1. Colucci (2010) Am Fam Physician 82(8): 942-52 [PubMed]
  2. Delacretaz (2006) N Engl J Med 354(10): 1039-51 [PubMed]
  3. Helton (2015) Am Fam Physician 92(9): 793-800 [PubMed]
  4. Kumar (2006) Cardiol Clin 24(3): 427-37 [PubMed]

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