atrial fibrillation

Question 1

rate control therapy typically involves

Answer 1

the use of beta blockers or nondihydropyridine calcium channel blockers

Question 2

rhythm control strategies usually include

Answer 2

synchronized electrical cardioversion, the use of pharmacological antiarrhythmics (e.g., flecainide, propafenone, or amiodarone), and ablation of the arrhythmogenic tissue.

Question 3

Afib with RVR

Answer 3

Ventricular rate > 100–110/minute (tachycardic Afib)

Question 4

Afib with SVR (slow Afib)

Answer 4

Ventricular rate < 60/minute (bradycardic Afib or slow Afib)

Question 5

ECG findings in Afib

Answer 5

P waves are indiscernible.
Fibrillatory waves (f waves) are seen instead at a frequency of 300–600/minute
PR intervals: not distinguishable
Typically narrow QRS complex (< 0.12 seconds)
Wide QRS complex may be seen in some situations

Question 6

Fibrillatory waves

Answer 6

may be hard to distinguish from artefact
Recent-onset Afib: prominent, coarse f waves with higher amplitude in leads V1, II, III, and aVF
Chronic Afib: f waves have low amplitudes and may appear as an undulating baseline.

Question 7

Wide QRS complex Afib

Answer 7

Aberrant conduction, e.g., bundle branch block or preexcitation (as seen in Afib with WPW)
Complete AV block with a ventricular escape rhythm
Ashman phenomenon: intermittent aberrant ventricular conduction results in isolated or short runs of wide QRS complexes

Question 8

PE, ACS and CHF in the setting of Afib

Answer 8

Afib can independently cause elevated D-dimer, troponin, and BNP levels. Interpret these findings along with the overall clinical suspicion for underlying PE, ACS, and/or CHF

Question 9

lab studies for new Afib

Answer 9

CBC: assessment for anemia and signs of infection
Serum electrolytes (Na+, K+, Mg2+, and Ca2+): to identify electrolyte imbalances
BUN, serum creatinine, and liver chemistries: to identify abnormal renal or liver function (risk factors for AFib)
TFTs: to screen for thyrotoxicosis

Question 10

Morphological TTE findings

Answer 10

Structurally normal heart (more common in young people)
Left atrial thrombus
Moderate to severe mitral stenosis or presence of a mechanical heart valve (previously known as valvular Afib) is associated with a significantly increased risk of thromboembolic events.
Other valvular heart disease or no valvulopathy (previously known as nonvalvular Afib)
Atrial enlargement

Question 11

Functional TTE findings

Answer 11

Chaotic atrial movements that are not coordinated with ventricles
Decreased left atrial compliance and volume (this increases risk of thromboembolism)
Decreased LVEF (due to cardiomyopathy)

Question 12

Patients with Afib should always be evaluated for

Answer 12

mitral valve dysfunction

Question 13

hot spots for thrombogenesis in Afib

Answer 13

the atria and the left atrial appendage

Question 14

Electrophysiology study

Answer 14

in patients < 30 years of age in order to: [3][20]
Identify associated conduction abnormalities (e.g., preexcitation)
Identify lesions amenable to ablation (e.g., for pulmonary vein isolation)
Distinguish between ventricular tachycardia and Afib with aberrant conduction

Question 15

goals of rhythm control

Answer 15

Termination of Afib (or atrial flutter)
Restoration and maintenance of sinus rhythm
Improvement of symptoms
Prevention of atrial remodeling

Question 16

goals of rate control

Answer 16

Decreased ventricular response rate to improve symptoms (in both acute and chronic Afib)
Decreased risk of arrhythmia-induced cardiomyopathy

Question 17

potential indicators for rhythm control over rate control

Answer 17

Age < 70 years
Highly symptomatic
Recent-onset Afib (< 12 months)
Failure of prior rate control strategy to control symptoms or achieve target heart rate
TTE findings (e.g., small left atrium, AV regurgitation, LV dysfunction)
Treated reversible cause of Afib

Question 18

potential indicators for rate control

Answer 18

Age ≥ 70 years
Milder symptoms
Recurrent or long-standing persistent Afib
Heart rate is easily controlled.
TTE findings (e.g., large left atrium, no or mild AV regurgitation, no or mild LV dysfunction)
Untreated reversible cause of Afib
High risk of thromboembolism
High risk of adverse reactions to cardioversion

Question 19

Planned electrical cardioversionPlanned electrical cardioversion

Answer 19

Gradually increasing strengths of current (synchronized with the R wave) are administered under sedation until sinus rhythm is restored.
The adjunctive use of antiarrhythmic drugs prior to shock delivery increases the likelihood of success.

Question 20

interventional alternatives to anticoagulation

Answer 20

occlusion of the left atrial appendage (most common location for the formation of thrombus)
Options include
Percutaneous left atrial appendage occlusion
Surgical occlusion of the left atrial appendage
Considered in patients who have contraindications to anticoagulation and an increased risk of stroke.

Question 21

paroxysmal atrial fibrillation

Answer 21

when episodes are self-terminating, usually within 48 hours, but can continue for up to 7 days. Atrial fibrillation that is cardioverted (rhythm control) within 7 days is considered paroxysmal

Question 22

persistent atrial fibrillation

Answer 22

when episodes last longer than 7 days. Atrial fibrillation that is cardioverted (rhythm control) after 7 days is considered persistent

Question 23

when should patients with a fib be anti coagulated

Answer 23

Patients with atrial fibrillation should be treated with oral anticoagulant therapy unless they have a very low stroke risk or an unacceptably high bleeding risk.

Question 24

appropriate DOAC dosage for AF

Answer 24

apixaban

patient with at least 2 risk factors for bleeding (ie age 80 years or older, weight 60 kg or less, and serum creatinine 133 micromol/L or more): 2.5 mg orally, twice daily

all other patients: 5 mg orally, twice daily.

Do not use apixaban if calculated creatinine clearance (CrCl) is less than 25 mL/min.

Question 25

appropriate DOAC dosage for AF with a CrCl<15

Answer 25

rivaroxaban CrCl 50 mL/min or more: 20 mg orally, once daily CrCl 15 to 49 mL/min: 15 mg orally, once daily.

Question 26

what INR target should you target with warfarin

Answer 26

Adjust the warfarin dose to achieve an INR from 2 to 3. The INR range can be higher for patients with rheumatic mitral stenosis and/or a mechanical heart valve as the range can depend upon the type of valve lesion or prosthesis; seek specialist advice.

Question 27

for pharmacological cardioversion. For a patient with atrial fibrillation who has a left ventricular ejection fraction known to be greater than 40% and no significant coronary artery disease, flecainide is preferred for pharmacological cardioversion. A suitable regimen is:

Answer 27

flecainide 2 mg/kg (up to 150 mg) by intravenous infusion, over at least 10 minutes.

Question 28

for pharmacological cardioversion. For a patient with atrial fibrillation who has a left ventricular ejection fraction of 40% or less, or coronary artery disease, amiodarone is preferred for pharmacological cardioversion. A suitable regimen is:

Answer 28

amiodarone 300 mg by intravenous infusion, over 30 to 60 minutes, followed by 900 mg by intravenous infusion over 24 hours, if required .

Question 29

‘Pill-in-the-pocket’ cardioversion

Answer 29

the use of a single oral dose of flecainide to restore sinus rhythm; it is self-administered by patients at home. Pill-in-the-pocket cardioversion is used under specialist supervision by selected patients with infrequent symptomatic episodes of atrial fibrillation. The flecainide dose is best taken in combination with a single dose of an AV nodal blocking drug (eg a beta blocker, diltiazem, verapamil) to decrease the risk of conversion to atrial flutter with 1:1 conduction.

Question 30

to maintain sinus rhythm in patients with atrial fibrillation who have coronary artery disease and normal left ventricular function. A suitable regimen is:

Answer 30

sotalol 40 mg orally, twice daily, increasing if required up to 160 mg twice daily.

Question 31

to maintain sinus rhythm for patients with atrial fibrillation who have a left ventricular ejection fraction known to be greater than 40% and no significant coronary artery disease.

Answer 31

flecainide 50 mg orally, twice daily, increasing if required up to 150 mg twice daily.

Question 32

long term use if flecainide or sotalol are not suitable to maintain sinus rhythm in patients with atrial fibrillation

Answer 32

amiodarone 200 mg orally, 3 times daily for 1 week, then twice daily for 1 week, then once daily.

Question 33

beta blockers for rate control of AF

Answer 33

atenolol 25 mg orally, daily, increasing if required up to 100 mg daily OR 1metoprolol tartrate 25 mg orally, twice daily, increasing if required up to 100 mg twice daily.

Question 34

for rate control for AF in patients with a left ventricular ejection fraction of 40% or less

Answer 34

use one of the beta blockers recommended for heart failure (carvedilol, bisoprolol, nebivolol or metoprolol succinate) instead of atenolol or metoprolol tartrate

Question 35

Nondihydropyridine calcium channel blockers for rate control of atrial fibrillation

Answer 35

If beta blockers are contraindicated, not tolerated or do not control ventricular rate in patients with atrial fibrillation Avoid diltiazem or verapamil in patients with a left ventricular ejection fraction of 40% or less because these drugs have negative inotropic effects. diltiazem immediate-release 60 mg orally, 2 or 3 times daily; titrate to response and tolerability [Note 5]. Maximum dose 360 mg daily in divided doses OR 1verapamil immediate-release 40 mg orally, twice daily, increasing if required up to 80 mg orally, 2 or 3 times daily; titrate to response and tolerability. Maximum dose 480 mg daily in divided doses.

Question 36

Once the appropriate dose of ndHP calcium channel blocker has been established, consider switching to

Answer 36

consider switching to the modified-release formulation of diltiazem or verapamil. If the risk of adverse effects is low (eg younger patients) consider using the modified-release formulation as initial therapy for rate control. Use: 1diltiazem modified-release 180 mg orally, daily, increasing if required up to 360 mg daily [Note 5] OR 1verapamil modified-release 180 mg orally, daily, increasing if required up to 480 mg daily.

Question 37

Digoxin for rate control of atrial fibrillation is not first line because

Answer 37

Digoxin is not a first-line drug for the treatment of atrial fibrillation because it may not control exercise-induced tachycardia when used alone.

Question 38

digoxin may be useful when

Answer 38

It is a useful addition: if beta blockers or nondihydropyridine calcium channel blockers do not control heart rate in patients with both atrial fibrillation and heart failure in whom other drugs are contraindicated or may need to be introduced very slowly (eg beta blockers).

Question 39

digoxin dosage

Answer 39

A suitable digoxin regimen for long-term rate control is: digoxin 62.5 to 250 micrograms orally, once daily, depending on age, body weight and kidney function.