Narrow-complex tachycardia


  • Heart rate > 100 bpm
  • Originates above the ventricles

Clinical Features

Differential Diagnosis

Narrow-complex tachycardia

Wide-complex tachycardia

Assume any wide-complex tachycardia is ventricular tachycardia until proven otherwise (it is safer to incorrectly assume a ventricular dysrhythmia than supraventricular tachycardia with abberancy)

^Fixed or rate-related


Differential A.Rhythm A.rate A.morphology Vagal/adenosine
A fib Irregular >350 Fibrillatory (V1) Incr. AV block
A Flutter Regular >250, <350 Sawtooth (II, III, AVF) Incr. AV block
A Tach Regular >100 Neg in II, III, AVF Nothing
AVNRT (SVT) Regular >160 No p's → NSR
Junctional Regular >100, <150 No p's or retrograde p's Nothing
MAT Irregular >100 >3 distinct p shapes Transient slowing
Sinus tachycardia Regular

>100 <180

Normal Transient slowing

Flutter vs coarse AFib: determine atrial regularity by taking big bites


Narrow Regular Tachycardia

  • Sinus tachycardia
    • Treat underlying cause
  • SVT
    • Vagal maneuvers (convert up to 25%)
    • Adenosine 6mg rapid IV push if patient hemodynamically stable (unstable should proceed directly to electrical cardioversion)
      • Can follow with repeat dose of 6 mg or 12mg if initially fails
      • If adenosine fails, initiate rate control with calcium channel blocker or beta blocker or use synchronized cardioversion
        • Diltiazem 15-20mg IV, followed by infusion of 5-15mg/hr
        • Metoprolol 5mg IVP x 3 followed by 50mg PO
    • Synchronized cardioversion (50-100J)
      • Provide sedation prior to synchronized cardioversion if patient is hemodynamically stable
  • Atrial flutter
    • Stable: Consider rate control to HR < 110 bpm
    • Unstable: Synchronized cardioversion; start at 50J

Narrow Irregular Tachycardia

  • Multi-focal atrial tachycardia (MAT)
    • Treat underlying cause (hypokalemia, hypomagnesemia)
    • Consider diltiazem
    • Avoid beta blockers unless they are already known to be tolerated, as airway disease often co-morbid
    • If not symptomatic and rate < 110/120 bpm, may not require treatment (e.g., patient with MAT secondary to COPD)
  • Sinus Tachycardia with frequent PACs
    • Treat underlying cause
  • A fib / A Flutter with variable conduction (see also Atrial Fibrillation with RVR)
    • Check if patient has taken usual rate-control meds
      • If missed dose, may provide dose of home medication and observe for resolution
    • Determine whether patient is better candidate for rate control or rhythm control [1]
      • Rate control preferred with:
        • Persistent A fib
        • Less symptomatic patients
        • Age 65 or older
        • Hypertension
        • No heart failure
        • Previous failure to cardiovert
        • Patient preference
      • Rhythm control preferred with:
        • Paroxismal or new A fib
        • More symptomatic patients
        • Age < 65 years
        • Heart failure clearly exacerbated by A fib
        • No history of rhythm control failure
        • Patient preference
    • Rate control with:
    • Rhythm conversion with:

Atrial fibrillation with RVR/flutter

Junctional tachycardia


  • Stable patients without serious comorbid illness who are adequately rate or rhythm controlled can be discharged home with follow-up
  • Patients with acute underlying cause may require admission
  • Patients who cannot achieve asymptomatic rate or rhythm control may require admission

See Also

External Links




  1. Frankel, G. et al. (2013) Rate versus rhythm control in atrial fibrillation. Canadian Family Physician 59(2), 161 - 168