AF

Question 1

Atrial Fibrillation
Classification (AHA 2014)

Answer 1

->Paroxysmal → Terminates spontaneously / with intervention within 7 days of onset
->Persistent → Continuous AF > 7 days
->Recurrent AF→ Two or more paroxysmal or persistent episodes of AF.
->Long-standing persistent → Continuous AF > 12 months
->Permanent → When further attempts to restore sinus rhythm are stopped

Question 2

Risks of AF

Answer 2

• Haemodynamic instability
• Systemic embolisation → stroke
• Tachycardiomyopathy

Question 3

Diagnosis

Answer 3

->Suspicion: Irregularly irregular heart rate
on clinical examination or telemetry
* Confirmation with 12-lead ECG
=>ECG
1). Irregularly irregular rhythm
* At very high rates → may appear regular (“pseudo-regularization”)
2). Absence of P waves
-Replaced by fibrillation waves
-Best seen in inferior leads & right-sided precordial leads

->Heart Rate in AF
* Typical range (without AV nodal blocking meds): 120–180 bpm
* > 200 bpm → Consider AF with accessory tract (e.g., WPW)
* < 100 bpm → Suggests conduction disease
** * ⚠️ Caution: Cardioversion at HR < 100 may ↑ risk of bradycardia
**

Question 4

Common Causes of New-Onset AF in ICU

Answer 4

1). Electrolyte abnormalities
* Hypokalaemia
* Hypomagnesaemia

2). Drug induced/withdrawal
* β-agonists (norepinephrine, epinephrine, dobutamine)
* Alcohol (holiday heart syndrome)
* Substance use (cocaine, amphetamine, methamphetamine)

3). Sepsis

4). Respiratory failure
* Pulmonary embolism/pneumonia/Hypoxemia/Hypercapnia

5). Primary cardiac disease
* Myocardial ischaemia
* Pericarditis

6). Other precipitants
* Post-operative state (esp. cardiothoracic surgery)
* Pain
* Hypovolaemia or fluid overload
* Thyrotoxicosis
* Swan-Ganz catheterisation

Question 5

Evaluation of New-Onset AF
[8 things to look for ]

Answer 5

Basic Evaluation
* ECG
* Electrolytes (incl. magnesium)
* Troponin
* TSH

Additional Tests (as clinically indicated)
* If ECG/history suggest ischaemia → Echo
* If suspicion of PE → CT pulmonary angiography
* Review medication list
* Review for indwelling cardiac devices

Question 6

Overall Approach to AF

Answer 6

Question 7

Treatment Goals

Answer 7

• Address haemodynamic instability
• Ventricular rate control
• Reversion to sinus rhythm
• Maintenance of sinus rhythm
• Anticoagulation when appropriate

Question 8

Cardioversion
vs
No Cardioversion

Answer 8

=>Key question:
* Is AF itself causing the instability OR,
is AF a just marker of underlying instability?
=>Clues to guide assessment:
1). Heart rate
* HR <150 → less likely to cause haemodynamic instability
* The faster the rate, the more likely AF is the driver

2). Structural heart abnormalities
* Pulmonary hypertension, mitral stenosis, diastolic heart failure → dependent on atrial kick, tolerate AF poorly

3). WPW syndrome with RVR

=>DC cardioversion stabilises the patient only if AF is causing the instability
* ⚠️ If fast rate is compensatory (e.g. due to shock/sepsis), aggressive rate reduction may worsen perfusion

Question 9

Indications for Immediate DC Cardioversion

Answer 9

->Indicated if new-onset AF is clearly the cause of severe instability
- Pretreatment/post-treatment with amiodarone ± magnesium → improves success and maintenance of sinus rhythm

->AF with an Accessory Pathway (Wolff-Parkinson-White)

Question 10

AF in WPW syndrome
Mechanism
How to identify
Management

Answer 10

=>Mechanism: Accessory pathway directly connects atria to ventricles
* Normal AF → HR limited by AV node (120–180, often tolerated)
* AF + accessory pathway → both AV node & accessory pathway conduct
* Accessory pathway often has shorter refractory period → HR >200
* Risk of VT or cardiovascular collapse

->How to Identify-
ECG features:
* Irregularly irregular rhythm, extremely fast (>200)
* Wide-complex beats from accessory pathway conduction
* Variable morphology → some fusion complexes if AV node & accessory pathway fire together

=>Management:
* ⚠️ Avoid AV nodal blockers (β-blockers, CCBs, amiodarone) → may allow accessory pathway dominance
* Preferred antiarrhythmics: Procainamide or Ibutilide
* DC cardioversion → treatment of choice if unstable (fast, effective)

Question 11

Performing DC cardioversion
->Pretreatment
->Sedation/Analgesia
->Pad position
->Ventilator disconnection
->Synchronization
->Highest energy

Answer 11

->1). **Pretreatment **with antiarrhythmics- eg Amiodarone if tiime allows
->2). sedation- Midazolam foll by ketamine- light sedation, not complete anaesthesia
Anterolateral position of pads preferred to A-P–> EPIC trial
->3). Hyperinflation may impair energy transfer–> condider disconnecting ventilator for a v. short period while delivering shock to allow de- inflation if saturation permits
->4). Synchronized shock
->5). use highest energy - higher chance of reversal, lesser chance of VT even if not synchronized properly

Question 12

AF stabilization Package

Answer 12

=>Core Principle
* The most important intervention is usually treating the underlying causes of AF.
* Risk: Over-focusing on antiarrhythmics and cardioversion → may miss reversible drivers.

> Treat haemodynamic instability-Optimize volume status, support MAP with vasopressors,
-> Electrolyte correction
-> Treat pain/ anxiety
-> Correct Hypoxia
->* CPAP for heart failure
* BiPAP for COPD
* HFNC for pneumonia

Question 13

Rate control vs Rhythm control

Answer 13

->No ICU RCTs comparing rate vs rhythm control. No clear survival benefit rhythm vs rate according to available evidence.
->Composite endpoints (death, stroke, recurrent hospitalisation) → favour rate control

=>Rhythm control superior in:
1->Haemodynamic intolerance of AF
- Pulmonary hypertension
- Valvular heart disease (esp. mitral stenosis)
- Diastolic dysfunction

2-> HFrEF (restoration of sinus rhythm may ↑ EF)

3-> New-onset AF (NOAF) during critical illness

4-> Atrial flutter → often stuck HR ~150, difficult to rate-control

5-> Failure of rate control → uncontrolled HR despite agents

Question 14

New-Onset AF (NOAF)

Answer 14

Definition
* AF developing during hospitalisation for critical illness in a patient with no prior AF.
* Prevalence: ~10% in septic shock.
* Natural history: often reverts spontaneously with resolution of illness.
* Associated with ↑ mortality, but unclear if causal vs marker of severity.

Question 15

Arguments for Rhythm Control in NOAF

Answer 15

1). Stroke prevention: risk relates to AF duration (>48h ↑ risk). Early cardioversion ↓ duration.
2). Prevent chronic AF: prolonged AF → electrical remodelling (“AF begets AF”). Early cardioversion ↑ chance of long-term sinus rhythm.
3). Improve cardiac function: restoration of atrial kick may improve CO.
4). Dual benefit of therapy: Mg and amiodarone → rate control even if rhythm conversion fails.

Question 16

Rhythm control strategy

Answer 16

Strategy:
->Magnesium infusion- Target -1.5-2.0mmol/l
->Amiodarone
->Cardioversion- if unsuccessful- likely unresolved pathology driving AF eg- sepsis/LA dilatation
-After Cardioversion, Continue amiodarone until critical illness resolves → reduces recurrence

Question 17

Rate Control Strategy

Answer 17

->Step 1 – Set a Safe HR Goal
* Outpatitients-<110/min
* ICU patients:
- Target often <130 bpm (individualised)
* Avoid “normalising” HR (<100) in unstable patients → may ↓ CO
* Tachycardia may be compensatory; allow variation over time

->Step 2 – Select an Agent
Options:
* Digoxin
* Amiodarone
* β-blockers (usually metoprolol)
* Diltiazem
Amiodarone most commonly used in a setting of hypotension
Digoxin- unlikely to be successful in ICU patients with ⬆️ed sympathetic tone.

Options->BAD->beta blockers; amiodarone; digoxin

Question 18

Q what are the challanges of managing AF in critically ill patients?

Answer 18

1->Difficult control due to higher sympathetic drive, unresolved precipitating factors eg- sepsis, Use of catecholamines as a driving factor for AF,
2->iInability to use many drugs eg- beta blockers/ CCBs due to associated shock/ hypotension
3->Digoxin often unhelpful due to higher sympathetic drive
4->Higher stroke risk due to associated inflammation
5->Higher risk of bleeding if anticoagulated
(renal dysfunction, coagulopathy, invasive procedures)
6->Risk scores (CHA₂DS₂-VASc, HAS-BLED) are not validated in ICU->difficult to balance bleeding risk with stroke risk.

Question 19

Anticoagulation in Atrial Fibrillation – Critically Ill Patients

Answer 19

->Stroke risk in critically ill patients is higher than outpatient population due to inflammation
->They also have multiple bleeding risk factors:
* Antiplatelet therapy
* Renal dysfunction
* Invasive procedures

->Risk scores (CHA₂DS₂-VASc, HAS-BLED) are not validated in ICU → difficult to balance stroke vs bleeding risk.

Question 20

Evidence for anticoagulation on New-Onset AF (NOAF)

Answer 20

=>No high-quality evidence supporting anticoagulation in NOAF secondary to critical illness.
->Retrospective studies:
* Anticoagulation ↑ bleeding risk without a significant↓in stroke risk.
* Findings robust, even after propensity matching

=>Current Practice

->New-Onset AF (NOAF)
* For most critically ill patients, risks of anticoagulation > benefit.
* Exceptions: high stroke risk + low bleeding risk → anticoagulation may be beneficial.
* Canadian 2020 guidelines:
* “In some cases (e.g., sepsis), IV anticoagulation ↑ bleeding risk but does not ↓ ischemic events.”
* If AF persists for weeks → more likely to evolve into ongoing AF → anticoagulation becomes more beneficial.

Question 21

Chronic AF
NON- VALVULAR

Answer 21

->Risk Assessment
* CHA₂DS₂-VASc score → calculates stroke risk.

->Warfarin
* ↓ Relative Risk of stroke by ~62%
* Risk of embolic stroke doubles if INR <2
* Target INR = 2–3

Aspirin
* Less effective than warfarin
* ↓ Relative Risk of stroke by ~22%

Warfarin + Antiplatelet
* No benefit compared to warfarin alone

NOACs (DOACs)
* Dabigatran, Apixaban → superior to warfarin
* Greater stroke reduction
* ↓ Intracranial haemorrhage
* Dabigatran → rapid reversal available (Idarucizumab)
* Rivaroxaban → non-inferior to warfarin

Question 22

Chronic AF
Valvular AF

Answer 22

->Indications
* Warfarin is indicated
* Direct thrombin inhibitors & factor Xa inhibitors → contraindicated

Monitoring
* Ideal INR 2–3
* Systolic BP <135 mmHg
* Avoid antiplatelet drugs

Question 23

Temporary Cessation of Anticoagulation in AF

Answer 23

• Non-valvular AF + CHA₂DS₂-VASc <2 –»
  Can withhold anticoagulation, minimal risk
• Non-valvular AF + CHA₂DS₂-VASc ≥2–»
  -Manage like valvular AF

=>Patients Requiring Coronary Artery Stenting
* Non-valvular AF + CHA₂DS₂-VASc <2-»Stop warfarin
* Use dual antiplatelet therapy (aspirin + clopidogrel)

*	Valvular AF OR Non-valvular AF + CHA₂DS₂-VASc ≥2->Continue warfarin
&	Add aspirin + clopidogrel

Question 24

Acute Management of Atrial Flutter

Answer 24

->Atrial flutter is usually a short-lived transitional state → may degenerate into AF or convert to sinus rhythm.
->Often resembles new-onset AF (NOAF).

=>Management is broadly similar to AF, but rhythm control is often more effective because:
1). Rate control difficult – HR often “stuck” at ~150 bpm.
2). Flutter is transient and relatively easy to cardiovert to sinus rhythm.

=>Rhythm control:
* Often attempted but may fail.
* Electrical cardioversion: highly effective, but requires sedation.
* Ibutilide ⚡: generally effective
* Amiodarone ⚡: less effective for acute cardioversion, but useful for ventricular rate control

->Anticoagulation:
* Modelled on AF treatment.
* Thromboembolic risk may be lower than in AF

=>Chronic Management of Atrial Flutter
* Catheter ablation: effective, preferred for definitive treatment.
* Medication therapy:
* 1st line: Rate control → β-blocker, diltiazem, or verapamil.
* 2nd line: Rhythm control → Amiodarone.

Question 25

**RF Ablation**

Answer 25

-> Most paroxysmal AFs arise from junction of LA and Pulmonary veins ->Ablation-> superior patient outcomes in a setting of HF ->Complications: -Perforation -TIA/Stroke -Pulmonary oedemadue to pulmonary vein stenosis -Recurrent AF