Atrial fibrillation with rapid ventricular response

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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 tachycardia-induced cardiomyopathy. 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 preexcited Afib, Afib with aberrant conduction, 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 ECG findings of atrial flutter 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 treatment of Afib with RVR.

See “Atrial fibrillation” for a comprehensive diagnosis and long-term management of Afib and atrial flutter.

See “Etiology of atrial fibrillation.”

See also “Clinical features of atrial fibrillation” and “Clinical features” in “Atrial flutter.”

• Rapid ventricular response (RVR): a ventricular rate > 100–110/minute occurring in response to a supraventricular tachyarrhythmia ^[2][3][4]
  • 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 wide QRS) 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 ^[4]
  • Palpitations
  • Fatigue
  • Dyspnea
  • Lightheadedness
  • Tachycardia
  • May be asymptomatic
• Unstable Afib with RVR: more likely to occur in patients with underlying cardiopulmonary disease and/or higher heart rates ^[4]
  • Clinical features of cardiogenic shock
  • Clinical features of acute heart failure
  • Ischemic chest pain
  • Altered mental status

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. ^[4]

The following focuses on acute management of Afib with RVR and atrial flutter with RVR. For long-term therapy, see “Management of atrial fibrillation” and “Treatment” in “Atrial flutter.”

Initial management ^[5][6]

• Evaluate hemodynamic stability using the ABCDE approach.
• Establish IV access.
• Begin continuous cardiac monitoring and pulse oximetry.
• Obtain confirmatory 12-lead ECG and other Afib diagnostics.
• Identify and treat reversible causes of Afib.

Unstable Afib with RVR ^[5][6]

Emergency electrical cardioversion

• Most patients: Perform synchronized electrical cardioversion ^[7]
  • Afib with RVR: 120–200 J biphasic
  • Atrial flutter with RVR: 50–100 J biphasic
• Irregular WCT (e.g., due to preexcited Afib): Consider unsynchronized cardioversion. ^[8]

Supportive management

• Immediate hemodynamic support with judicious IV fluids and cautious use of vasopressors
• Consider procedural sedation for cardioversion.
• Begin pericardioversion anticoagulation for Afib as soon as possible if Afib onset ≥ 48 hours or unknown and the patient is not already anticoagulated.

Manage unstable Afib with immediate synchronized electrical cardioversion. Do not delay emergency electrical cardioversion for anticoagulation.

Stable Afib with RVR

Clinical decision-making resembles the approach to a new diagnosis of Afib without RVR. If the diagnosis is uncertain, follow the approach for undifferentiated stable, irregular narrow-complex tachycardia.

• Rate control vs. rhythm control
  • Onset ≥ 48 hours or unknown ^[9][10]
    • Rate control is preferred initially.
    • Defer rhythm control until pericardioversion anticoagulation for Afib is complete or TEE for Afib has ruled out thrombi.
  • Onset < 48 hours: Consider early rhythm control or rate control on an individual basis.
• Anticoagulation for Afib
  • Already prescribed: Check INR or evaluate adherence to DOACs.
  • Not prescribed: Determine the need for pericardioversion anticoagulation for Afib if rhythm control is selected.
• Comorbid conditions that affect management
  • See “Management of Afib with ACS.”
  • See “Management of Afib with chronic HF.”

Disposition ^[4]

• Patients presenting to the ED with RVR typically undergo a trial of rate control or rhythm control 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:
  • RVR resolved OR successful cardioversion
  • AND underlying reversible Afib trigger adequately treated
• Follow local protocols and consider cardiology consultation prior to discharge. ^[11]

See “Afib diagnostics” for details.

• 12-lead ECG: to confirm ECG findings in Afib or ECG findings of atrial flutter and identify underlying etiology
• Routine laboratory studies: e.g., CBC, BMP, coagulation panel
• Studies to identify reversible causes of Afib
  • Laboratory studies (e.g., troponin, BNP, septic workup, D-dimer, TFTs, serum toxicological screen)
  • Imaging (e.g., CXR, TTE, CTPA, POCUS)

Irregularly irregular NCT with a rate > 100–110/minute and no discernable P waves on ECG strongly suggests Afib with RVR.

Regular NCT with a rate of 150/minute with sawtooth P waves on ECG suggests rapid atrial flutter with 2:1 conduction. Treatment is the same as for rapid Afib.

Exercise caution if there is a WCT since the differential diagnoses include preexcited Afib, Afib with aberrant conduction, atrial flutter with aberrant conduction or preexcitation, ventricular tachycardia, and other SVT with aberrancy. 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 “Rhythm control vs. rate control” for details); for unstable Afib, emergency electrical cardioversion is the treatment of choice.

Administer rate control with IV medications and/or rhythm control for Afib with RVR in monitored acute care settings.

Rate control ^[5][9]

For long-term maintenance therapy, see “Rate control” in “Atrial fibrillation.”

• Goals
  • Stabilize RVR to a lower resting heart rate, e.g., < 80/minute (HR < 110/minute may be acceptable in asymptomatic patients without LV dysfunction). ^[5]
  • Prevent complications of tachycardia: e.g., unstable Afib, tachycardia-induced cardiomyopathy
• Clinical applications
  • Initial management when Afib onset is ≥ 48 hours or unknown
  • Rhythm control is undesirable (e.g., due to risks or patient preference)

Avoid rate control medications in the management of preexcited Afib as they are all AV nodal blockers that can precipitate Vfib due to uncontrolled ventricular conduction via the accessory pathway. ^[5][7]

Options ^[5][7]

IV agents are recommended in the acute setting; consider combination with oral medications. ^[5][12]

• First-line
  • Beta blockers
    • Metoprolol ^[5][7]
    • Esmolol ^[5][7]
    • Propranolol ^[5][7]
  • Nondihydropyridine calcium channel blockers (ndHP CCBs)
    • Diltiazem ^[5][7]
    • Verapamil ^[5][7]
• Second-line (e.g., patients with contraindications to first-line options or refractory symptoms)
  • Digoxin (caution in elderly patients) ^[5][7]
  • Amiodarone ^[5][7]

Avoid IV beta blockers and ndHP CCBs in patients with LV dysfunction and acute decompensated heart failure as these can compromise hemodynamic function. ^[5][7]

For rate control in pregnant individuals, beta blockers are preferred. CCBs and digoxin can be used in consultation with a specialist. Amiodarone can be harmful and should be avoided. ^[13][14]

Rhythm control (e.g., cardioversion) ^[5][6][9]

Can safely be used to convert Afib with RVR back to sinus rhythm in select patients for whom this is desirable.

• Goals
  • Convert Afib with RVR back to sinus rhythm
  • Prevent complications of tachycardia: e.g., unstable Afib, tachycardia-induced cardiomyopathy
  • Reduce the need for anticoagulation for Afib in select patients
  • Improve outcomes for patients with cardiovascular comorbidities (e.g., heart failure) ^[15][16]
• Clinical applications
  • Afib onset < 48 hours PLUS rate control is undesirable (e.g., due to risk or patient preference)
  • Afib onset ≥ 48 hours PLUS:
    • Anticoagulation for Afib completed for ≥ 3 weeks
    • OR thrombi ruled out on TEE for Afib

Options ^[5]

• Planned electrical cardioversion
  • Can be first-line or used when pharmacological cardioversion is unsuccessful
  • Consider repeat electrical cardioversion if the first attempt is unsuccessful
  • Use procedural sedation for cardioversion whenever possible.
• Pharmacological cardioversion ^{[5][6][7][17]}
  • Evaluate for contraindications to antiarrhythmic agents.
  • Flecainide, dofetilide, propafenone, and ibutilide are preferred options.
  • IV amiodarone is also appropriate.
  • See “Pharmacological cardioversion agents for Afib” for dosages.
• Ottawa aggressive protocol ^[18][19]
  • A protocol for rhythm control in the ED for eligible patients < 48 hours from Afib onset followed by discharge after a 1-hour observation and rapid cardiology follow-up
  • Involves pharmacologic cardioversion using procainamide and, if unsuccessful, synchronized electrical cardioversion at 150–200 J (biphasic)
• Interventional cardioversion: usually cannot be performed on an urgent basis for Afib with RVR

Monitor for QTc prolongation and torsades de pointes in patients receiving dofetilide or ibutilide. ^[5]

Avoid flecainide and propafenone in patients with coronary artery disease and significant structural heart disease. ^[5]

Electrical cardioversion is preferred over pharmacological cardioversion for rhythm control in pregnant individuals. ^[13][14]

Consult cardiology early whenever complicating factors (e.g., ACS, chronic HF, preexcited Afib) are present or suspected alongside Afib with RVR.

Afib with acute coronary syndrome ^[5][6]

• Indications for urgent synchronized electrical cardioversion
  • Ongoing ischemia
  • Hemodynamic compromise
  • Inadequate rate control
• IV beta blockers
  • Generally preferred for rate control
  • Avoid in patients with decompensated heart failure, bronchospasm, and/or hemodynamic instability.
• Consider amiodarone or digoxin in patients with hemodynamic compromise or severe LV dysfunction and heart failure.

Afib with heart failure ^[5][20]

See also “Tachycardia-induced cardiomyopathy.”

• Stable chronic HF
  • Initial rate control options for stabilization
    • Reduced ejection fraction: IV beta blockers, digoxin, or amiodarone
    • Preserved ejection fraction: IV beta blockers, digoxin, amiodarone, or IV ndHP CCBs
  • Once RVR is stabilized, consider rhythm control as definitive management for recent onset Afib with HF (See “Rate control vs. rhythm control” for details). ^[15][16][21]
• Acute decompensated heart failure (ADHF)
  • Unstable Afib: urgent synchronized electrical cardioversion
  • Stable Afib: management based on the suspected cause of ADHF
    • Afib causing ADHF : rhythm control
    • Afib not causing ADHF: rate control or rhythm control
      • Target heart rate < 120/minute ^[20]
      • Amiodarone or digoxin are preferred. ^[5]
      • Use beta blockers with caution ^[5]
      • Avoid CCBs. ^[5]

Preexcited Afib (Afib with WPW)

WPW is the most common preexcitation pattern, however, other accessory pathways may also underlie this presentation.

Diagnosis

• Heart rate may be very high (> 200–250/minute) ^[22]
• Wide QRS complexes are commonly seen because of ventricular preexcitation.
• Appearance can resemble polymorphic Vtach ^[23]

Consider preexcited Afib in at-risk patients with irregularly irregular WCT.

Management of preexcited Afib ^[24]

See “Stable, wide-complex tachycardia” for details on differentiating preexcited Afib from other irregular WCTs.

• First-line: unsynchronized electrical cardioversion at 200 J (biphasic) ^{[5][7][8][25]}
• Second-line: Consider the following antiarrhythmics in consultation with cardiology. ^[5][9]
  • Procainamide
  • OR ibutilide

Avoid AV nodal blockers and amiodarone in patients with preexcited Afib as these can trigger Vfib.

Hemodynamic instability is common in patients with preexcited Afib and other irregular WCTs (e.g., polymorphic Vtach). When in doubt, treat with electrical cardioversion!

• ABCDE approach
• Establish IV access, continuous cardiac monitoring, and pulse oximetry.
• Confirm the diagnosis with an ECG.
• Determine if Afib is stable or unstable.
  • Unstable Afib: Urgent electrical cardioversion
  • Stable Afib: Determine duration of symptoms
    • Onset ≥ 48 hours: Rate control
    • Onset < 48 hours: Rate control or rhythm control
• Evaluate for comorbid conditions (e.g., ACS, chronic HF, preexcited Afib).
• Identify and treat reversible causes of Afib.
• Determine the need for pericardioversion anticoagulation for Afib.
• 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.