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EM - EBMedicine Summaries > Atrial Fibrillation > Flashcards

Atrial Fibrillation Flashcards

1
Q

Approach to the unstable patient with AFib?

(1) Summary Steps
(2) Details

A 
Summary
Step 1: Initial Management
Step 2: Is there another cause?
Step 3: Is immediate shock needed?
Step 4: Is there an accessory pathway?
Step 5: Treat

Step 1:
IV, O2, Monitor, Trial 20-40cc/kg bolus

Step 2:

  • Signs of other causes of shock (septic, hypovolemic, obstructive, cardiogenic)
  • Rapid Ultrasound (LV, RV, IVC, Fast, Aorta)

Step 3:

  • Hemodynamically unstable?
  • AF with pre excitation and very ventricular rate
  • Candidate for immediate DCC?

If yes:

  • Immediate 200J biphasic cardioversion
  • Consider lower energy for Aflutter
  • Anticipate Failure

Step 4:
- Signs of pre excitation syndrome?

If yes:

  • Amiodorone, Procainamide, Ibutilide
  • Consider vasopressors, calcium gluconate, DCC

Step 5:

  • Treat the POTENTIALLY UNSTABLE patient
  • Diltiazem (0.2mg/kg SLOW IV bolus -or- 2.5mg/min gtt, MAX dose 50mg)
  • OR Amiodarone
  • OR Magnesium
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2
Q

Approach to the unstable patient with AFib?

(1) Summary Steps
(2) Details

A 
Summary
Step 1: Initial Management
Step 2: Is there another cause?
Step 3: Is immediate shock needed?
Step 4: Is there an accessory pathway?
Step 5: Treat

Step 1:
IV, O2, Monitor, Trial 20-40cc/kg bolus

Step 2:

  • Signs of other causes of shock (septic, hypovolemic, obstructive, cardiogenic)
  • Rapid Ultrasound (LV, RV, IVC, Fast, Aorta)

Step 3:

  • Hemodynamically unstable?
  • AF with pre excitation and very ventricular rate
  • Candidate for immediate DCC?

If yes:

  • Immediate 200J biphasic cardioversion
  • Consider lower energy for Aflutter
  • Anticipate Failure

Step 4:
- Signs of pre excitation syndrome?

If yes:

  • Amiodorone, Procainamide, Ibutilide
  • Consider vasopressors, calcium gluconate, DCC

Step 5:

  • Treat the POTENTIALLY UNSTABLE patient
  • Diltiazem (0.2mg/kg SLOW IV bolus -or- 2.5mg/min gtt, MAX dose 50mg)
  • OR Amiodarone
  • OR Magnesium
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3
Q

What are signs to be suspicious for accessory pathway in AFib? (4)

A

(1) Wide, bizarre QRS
(2) Ventricular rate > 250
(3) Hx of WPW
(4) Prior ECG with Delta-waves

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4
Q

What are signs to be suspicious for accessory pathway in AFib? (4)

A

(1) Wide, bizarre QRS
(2) Ventricular rate > 250
(3) Hx of WPW
(4) Prior ECG with Delta-waves

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5
Q

What should be considered with shock refractory AFib in the unstable patient

(1) Without accessory pathway
(2) With accessory pathway

A

(1) Without:
- Ibutilide (1mg over 10 minutes)
- OR-
- Rate Control Medications ]
- Diltiazem (0.2mg/kg slow bolus or 2.5mg/min gtt, MAX 50mg)
- Amiodarone
- Magnesium
- OR-
- Procainamide
- OR-
- Additional Shocks

Consider:

  • Calcium Gluconate
  • Vasopressors

(2) With
- Procainamide
- OR-
- Ibutilide (1mg over 1+ minute)
- OR-
- Amiodarone
- OR-
- Additional Shocks’

Consider:

  • Calcium Gluconate
  • Vasopressors
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6
Q

Approach to the stable patient with new-onset AFib?

(1) Summary Steps
(2) Details

A 
Steps:
Step 1: Is there an accessory pathway?
Step 2: Should we use B-blockers?
Step 3: Contraindication for CCB?
Step 4: CHF or Borderline stable?
Step 5: Treat

Step 1: Consider accessory pathway
If yes:
- Consider DCC, Procainamide, Amiodarone
- Consider Anticoagulation

Step 2: Should we use B-Blockers?

  • ACS, LV dysfunction, Thyrotoxicosis?
  • No contraindication? (e.g. asthma, acute CHF)

If yes:
- Beta-blocker for rate control

Step 3: Contraindication for CCB?
If yes:
- Esmolol, DCC, Magnesium, Amiodorone, or Digoxin with another agent

Step 4: CHF or borderline stable
If yes:
- Pretreat with 5-10cc calcium gluconate slow IV push

-AND-

  • Diltiazem (5mg slow IV push Q5M until HR50mg dose)
  • OR-
  • Diltiazem (2.5mg gtt until HR50mg dose)
  • OR-
  • Amiodarone (150mg bolus then gtt or repeat bolus)

-AND-

Consider Magnesium, Digoxin; Avoid Beta-blockers

Step 5: Treat!
- Diltiazem (0.25mg/kg bolus over 2 minutes followed bu 0.35mg/kg over 2 minutes every 15 minutes if inadequate response; hold for HR

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7
Q

Approach to the stable patient with new-onset AFib?

(1) Summary Steps
(2) Details

A 
Steps:
Step 1: Is there an accessory pathway?
Step 2: Should we use B-blockers?
Step 3: Contraindication for CCB?
Step 4: CHF or Borderline stable?
Step 5: Treat

Step 1: Consider accessory pathway
If yes:
- Consider DCC, Procainamide, Amiodarone
- Consider Anticoagulation

Step 2: Should we use B-Blockers?

  • ACS, LV dysfunction, Thyrotoxicosis?
  • No contraindication? (e.g. asthma, acute CHF)

If yes:
- Beta-blocker for rate control

Step 3: Contraindication for CCB?
If yes:
- Esmolol, DCC, Magnesium, Amiodorone, or Digoxin with another agent

Step 4: CHF or borderline stable
If yes:
- Pretreat with 5-10cc calcium gluconate slow IV push

-AND-

  • Diltiazem (5mg slow IV push Q5M until HR50mg dose)
  • OR-
  • Diltiazem (2.5mg gtt until HR50mg dose)
  • OR-
  • Amiodarone (150mg bolus then gtt or repeat bolus)

-AND-

Consider Magnesium, Digoxin; Avoid Beta-blockers

Step 5: Treat!
- Diltiazem (0.25mg/kg bolus over 2 minutes followed bu 0.35mg/kg over 2 minutes every 15 minutes if inadequate response; hold for HR

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8
Q

Whats the danger of combining IV CCB and B-blockers?

A

Complete heart block and dysrhythmias; both should not be given IV and in close succession; if patient is on oral agent, it is okay to give IV of the other;

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9
Q

What is the limitation of using Ibutilide?

A

Causes successful conversion in 40-50% of time; BUT has 8% risk of ventricular tachyarrhythmias (e.g. torsades), so give with magnesium and monitor for at least 4 hours after administration

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10
Q

What is the definition of a patient safe to discharge with new onset AFib?

A

1.

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11
Q

What are the canadian cardiology society recommendations for disposition with new onset AFib?

A

Admit if:

  1. New onset and related to decompensated CHF or MI
  2. If severely symptomatic and unable to achieve adequate rate control
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12
Q

What is the INR goal for mechanical valves?

A

> 2.5

  • recommendations are only for >2.5, not the 2.5-3.5 range commonly cited
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13
Q

What are the components to CHADS-VASc

A 
CHF : 1 point
HTN : 1 point
Age > 75: 2 points
DM : 1 point
Stroke : 2 points (includes TIA, embolic event)
Vascular dz (prior MI, PAD, Aortic Plaque) : 1 point
Age 65-74 : 1 point
Sex (female) : 1 point

0 points: no antiplatelets
1 point: start ASA
2+ points: start anticoagulation

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14
Q

What is the efficacy of VKAs versus anti platelets for decreasing the rate of stroke in AFib?
What about combining ASA and clopidogrel?

A

VKAs decrease stroke risk by 66%
ASA decreases stroke risk by only 22%

(2)
Stroke risk decreased to 6.8%/y (from 7.6%/y with ASA alone) but increases risk of major bleeding (2.0% vs 1.3%)

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15
Q

What is the definition of high risk vs low risk of thromboembolic events due to AFib?

A

High risk: > 4% per 100 patient years with ASA

Low risk:

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16
Q

What are the anticoagulation goals with cardioversion?

(1) Unstable patients
(2) Stable patients
(3) Alternative in stable patients

A

(1) Immediate Unfractionated Heparin Bolus and Gtt with goal PTT 1.5-2x normal, followed by oral anticoagulation for INR of 2-3 for at least 4 weeks
(2) Anticoagulation with goal INR 2-3 for 3 weeks prior and 4 weeks after
(3) Can get TEE to rule out atrial thrombus to avoid need for preceding anticoagulation, but MUST start anticoagulation after conversion

17
Q

What is the rate of thrombus formation in AFib

A

~13%

18
Q

What are the Class I recommended drugs for

(1) AF 7 days
(3) AF with pre-excitation

A 
(1)
Ibutilide
Dofetilide
Flecanide
Propafenone

(2)
Dofetilide

(3)
Ibutilide
Procainamide

19
Q

Agents for AFib Cardioversion: Ibutilide

(1) IV Dose
(2) Adverse Events

A

(1) 1mg over 10 minutes, repeat 1mg when necessary

(2) QT Prolongation –> Torsades

20
Q

Agents for AFib Cardioversion: Flecainide

(1) IV Dose
(2) Adverse Events

A

(1) 1.5-3.5mg/kg over 10-20 minutes

(2) Hypotension, Aflutter with RVR

21
Q

Agents for AFib Cardioversion: Propafenone

(1) IV Dose
(2) Adverse Events

A

(1) 1.5-2.0mg/kg over 10-20 minutes

(2) Hypotension, Aflutter with RVR

22
Q

Agents for AFib Cardioversion: Dofetilide

(1) IV Dose
(2) Adverse Events

A

(1) NO IV dose, Oral only but needs renal adjustment

2

23
Q

Agents for AFib Cardioversion: Dofetilide

(1) IV Dose
(2) Adverse Events

A

(1) NO IV dose, Oral only but needs renal adjustment

(2) QT prolongation

24
Q

Agents for AFib Cardioversion: Amiodarone

(1) IV Dose
(2) Adverse Events

A

(1) 5-7mg/kg IV over 30-60 minutes
- FOLLOWED BY 1.2-1.8g/d continue IV infusion -OR- divided oral doses until 10g TOTAL amiodarone is reached
(2) Hypotension, Bradycardia, QT prolongation –> Torsades, GI upset, Constipation, Phlebitis

25
Q

Agents for AFib Cardioversion: Procainamide

(1) IV Dose
(2) Adverse Events

A

(1) 1g over 60 minutes

(2) Hypotension, QT prolongation –> Torsades

26
Q

Agents for AFib Cardioversion: Procainamide

(1) IV Dose
(2) Adverse Events

A

(1) 1g over 60 minutes

(2) Hypotension, QT prolongation –> Torsades

27
Q

What is the efficacy of procainamide for conversion? Most common side effect?

A 
~55%
Temporary hypotension (~7%)
28
Q

What needs to be confirmed prior to chemical cardioversion?

A

That the patient has:

(1) Normal electrolytes
(2) Normal QTc interval

29
Q

Pretreatment for electrical cardioversion

(1) Whats the idea?
(2) What agents can be used?

A

(1) Pretreatment with certain agents can increase the success of DCC, particularly after unsuccessful DCC. Or, you can attempt chemical cardioversion and then use DCC if that is not successful (per Ottawa Aggressive Protocol)
(2)
Amiodarone
Flecainide
Ibutilide
Propafenone
Sotalol

30
Q

Pretreatment for electrical cardioversion

(1) Whats the idea?
(2) What agents can be used?

A

(1) Pretreatment with certain agents can increase the success of DCC, particularly after unsuccessful DCC. Or, you can attempt chemical cardioversion and then use DCC if that is not successful (per Ottawa Aggressive Protocol)
(2)
Amiodarone
Flecainide
Ibutilide
Propafenone
Sotalol

31
Q

What are the seven steps to the Ottawa Aggressive Protocol?

A
  1. Assessment
    • Stable without ischemia, hypotension, or acute CHF? • Onset clear and 3 wk
  2. Disposition
    • Home within 1 h after cardioversion
    • Usually no antiarrhythmic ppx or anticoagulation given
    • Arrange outpatient echocardiography if first episode
    • Cardiology follow-up if first episode or frequent episodes
  3. Patients not treated with cardioversion
    • Rate control with diltiazem IV (target heart rate 48 h, start warfarin
    • If CHADS score ≥ 1, consider warfarin and arrange early follow-up
32
Q

What are the seven steps to the Ottawa Aggressive Protocol?

A
  1. Assessment
    • Stable without ischemia, hypotension, or acute CHF? • Onset clear and 3 wk
  2. Disposition
    • Home within 1 h after cardioversion
    • Usually no antiarrhythmic ppx or anticoagulation given
    • Arrange outpatient echocardiography if first episode
    • Cardiology follow-up if first episode or frequent episodes
  3. Patients not treated with cardioversion
    • Rate control with diltiazem IV (target heart rate 48 h, start warfarin
    • If CHADS score ≥ 1, consider warfarin and arrange early follow-up
33
Q

Magnesium for AF

(1) Use
(2) Efficacy
(3) Side effects

A

(1) Slows AV node conduction; been shown to be effective at cardioversion but mostly used as an adjunct
(2) 50-60%
(3) Respiratory depression, hypotension, cardiac pauses

34
Q

Amiodarone for Rate Control

(1) When is it preferred over B-blockers and CCBs?
(2) Adverse effects
(3) Dose
(4) Timing of onset

A

(1)

  • When the negative ionotropy of B-blockers and CCB is a concern
  • When B-blockers and CCB are contraindicated (e.g. acute CHF)

(2) Caution when using amiodarone for rate control in patients at risk for thrombosis and not on anticoagulation due to potential for cardioversion

(3)
- Initial: 150mg IV over 10 days
- Maintenance: 0.5-1mg/min IV

(4)

35
Q

Evidenced Based Findings: AFib in Pregnancy

(1) Safety of DCC
(2) Which anticoagulant to use
(3) Which rate control agent to use
(4) Which chemical cardioversion agent to use

A

(1) DCC is safe during all trimesters if the patient is unstable or the AFib is deemed to be causing high risk to patient or fetus (Class I, Level C Evidence)
(2) Use LMWH or UFH during 1st trimester and during last month of pregnancy; use VKA during 2nd trimester until the last month of pregnancy (Class I, Level B Evidence)
(3) Use B-blockers or nondihydropyridine CCBs for rate control if needed, caution with B-blockers in first trimester (Class II, Level C Evidence)
(4) Use Flecainide or Ibutilide if chemical cardioversion is necessary, the patient has structurally normal heart, and DCC is contraindicated (Class II, Level C Evidence)

36
Q

Digoxin for Rate Control

(1) Why can it good?
(2) Why can it be bad?
(3) Dose
(4) Timing of onset

A

(1) Has negative chronotropy with positive ionotropy and no effective on SVR; so can be good in the unstable patient
(2) May not have effect for 3 hours, and can take 6 hours for full effect
(3)
- Initial: 0.25mg IV Q2H to total of 1.5mg
- Maintenance: 0.125mg-0.375mg IV/PO QD
(4) 30-180 minutes

37
Q

Digoxin for Rate Control

(1) Why can it good?
(2) Why can it be bad?
(3) Dose
(4) Timing of onset

A

(1) Has negative chronotropy with positive ionotropy and no effective on SVR; so can be good in the unstable patient
(2) May not have effect for 3 hours, and can take 6 hours for full effect
(3)
- Initial: 0.25mg IV Q2H to total of 1.5mg
- Maintenance: 0.125mg-0.375mg IV/PO QD
(4) 30-180 minutes

38
Q

Efficacy for rate control of Diltiazem versus Amiodarone or Digoxin?

A

Dilt shown to be more effective for rate-control than amio/dig in RCT

EM - EBMedicine Summaries (5 decks)

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