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Atrial fibrillation with rapid ventricular response (Afib with RVR) is Afib with a ventricular rate > 100–110/minute. Afib with RVR can lead to impairment of cardiac output and hemodynamic instability due to shortened ventricular filling time and increased myocardial oxygen demand. Long-term Afib with RVR may lead to . Affected individuals typically present with palpitations, but may be asymptomatic or also have signs of hemodynamic instability. Diagnosis is based on ECG findings. The typical appearance of Afib with RVR is an irregularly irregular narrow-complex tachycardia (NCT) without discernable P waves. The presence of a wide-complex tachycardia (WCT) raises the likelihood of , Afib with , and other WCTs, e.g., ventricular tachycardia (VT). Acute management depends on clinical stability, symptom duration, and comorbid conditions. Treatment typically involves rate control or rhythm control followed by the identification and management of reversible Afib triggers. Although the with RVR differ (e.g., usually a regular rhythm with a rate dependent on the conduction ratio), its initial management and stabilization are the same as the .
Rapid ventricular response (RVR): a ventricular rate > 100–110/minute occurring in response to a 
- RVR is often but not always associated with hemodynamic instability, depending on the patient's physiological reserve and the degree of tachycardia.
- Typically RVR in Afib is no greater than 150–170/min.
- RVR > 200/min suggests preexcited Afib (usually with ) or an alternate diagnosis (e.g., VT).
- Patients with a new diagnosis of Afib are more likely to be symptomatic at a given RVR rate.
- Stable Afib with RVR: can occur in patients without underlying cardiopulmonary disease and with HR < 150/min 
- Unstable Afib with RVR: more likely to occur in patients with underlying cardiopulmonary disease and/or higher heart rates 
Conduct a careful clinical evaluation to determine whether the tachycardia is the primary cause of hemodynamic instability or a response to shock due to an underlying condition (e.g., sepsis, hypovolemia, massive PE), especially in patients with longstanding Afib. 
Initial management 
- Evaluate hemodynamic stability using the .
- Begin pulse oximetry. and
- Obtain confirmatory 12-lead ECG and other .
- Identify and treat .
Unstable Afib with RVR 
Emergency electrical cardioversion
- Most patients: Perform 
- Irregular WCT (e.g., due to ): Consider . 
- IV fluids and cautious use of vasopressors with judicious
- Consider .
- Begin Afib onset ≥ 48 hours or unknown and the patient is not already anticoagulated. as soon as possible if
Stable Afib with RVR
- Comorbid conditions that affect management
- Patients presenting to the ED with RVR typically undergo a trial of or followed by a period of observation.
- Hospital admission is required for symptomatic patients unresponsive to ED management.
- Consider cardiology consult and ICU admission for patients with persistently unstable or refractory tachycardia.
- Consider discharge with close outpatient cardiology follow-up in stable, asymptomatic patients if:
- Follow local protocols and consider cardiology consultation prior to discharge. 
See “Afib diagnostics” for details.
- 12-lead ECG: to confirm or and identify underlying etiology
- Routine laboratory studies: e.g., CBC, BMP, coagulation panel
- Studies to identify
Irregularly irregular with a rate > 100–110/minute and no discernable on ECG strongly suggests .
Regular 150/minute with on ECG suggests rapid with 2:1 conduction. Treatment is the same as for . with a rate of
Exercise caution if there is a WCT since the differential diagnoses include , with , with or , , and other . These diagnoses require a specialized approach.
- See “Differential diagnosis of tachycardia.”
- See “Differential diagnosis of irregular, narrow-complex tachycardia.”
- See “Differential diagnosis of wide-complex tachycardia.”
- See “Differential diagnosis of SVT.”
- See “Dyspnea.”
- See “Chest pain.”
The differential diagnoses listed here are not exhaustive.
For stable patients, choose the optimal strategy based on the individual patient's risk profile in consultation with a specialist (see “unstable Afib, emergency electrical cardioversion is the treatment of choice.” for details); for
Rate control 
- Clinical applications
IV agents are recommended in the acute setting; consider combination with oral medications. 
- Second-line (e.g., patients with contraindications to first-line options or refractory symptoms)
Avoid IV beta blockers and in patients with and as these can compromise hemodynamic function. 
Rhythm control (e.g., cardioversion) 
- Clinical applications
- Planned electrical cardioversion
- Pharmacological cardioversion 
- Ottawa aggressive protocol 
- Interventional cardioversion: usually cannot be performed on an urgent basis for Afib with RVR
Afib with acute coronary syndrome 
- Indications for urgent synchronized electrical cardioversion
- IV beta blockers
- Consider amiodarone or digoxin in patients with hemodynamic compromise or severe LV dysfunction and heart failure.
Afib with heart failure 
See also “Tachycardia-induced cardiomyopathy.”
Stable chronic HF
- Initial options for stabilization
- Once RVR is stabilized, consider rhythm control as definitive management for recent onset Afib with HF (See “Rate control vs. rhythm control” for details). 
- Acute decompensated heart failure (ADHF)
Preexcited Afib (Afib with WPW)
- Heart rate may be very high (> 200–250/minute) 
- Wide QRS complexes are commonly seen because of ventricular preexcitation.
- Appearance can resemble 
Management of preexcited Afib 
See “WCTs.” for details on differentiating from other irregular
- First-line: unsynchronized electrical cardioversion at 200 J (biphasic) 
- Second-line: Consider the following antiarrhythmics in consultation with cardiology. 
Acute management checklist
- ABCDE approach
- Establish IV access, continuous cardiac monitoring, and pulse oximetry.
- Confirm the diagnosis with an ECG.
- Determine if Afib is stable or unstable.
- Evaluate for comorbid conditions (e.g., ACS, chronic HF, preexcited Afib).
- Identify and treat
- Determine the need for
- Consider cardiology consult and admission for further workup and/or cardiac monitoring.
- Admit to the ICU if the patient has unstable Afib or refractory tachycardia.