Atrial Fibrillation

Question 1

What is the pathophysiology of AF?

Answer 1

Irregular spontaneous depolarisation of the cells in the atria causing dyssynchronous atrial contraction which gives the atria a quivering appearance.

Question 2

What are common AF symptoms?

Answer 2

Irregularly irregular pulse, breathlessness, palpitations, chest discomfort.

Question 3

What can be done to diagnose AF?

Answer 3

12-lead ECG. If positive will present with no P-waves, a chaotic baseline, and an irregular ventricular rate.

Question 4

What medicines can be given for treatment of AF?

Answer 4

Rate control - beta-blocker or rate-limiting calcium channel blocker.

Question 5

What assessments are done after diagnosis with AF?

Answer 5

CHADSVASc (for stroke risk) and ORBIT (for bleeding risk)

Question 6

What can be prescribed for AF patients with a CHADVASc score of 2 or more.

Answer 6

Anticoagulant.

Question 7

What are first line anticoagulants?

Answer 7

Direct oral anticoagulants (DOACs) such as apixaban, rivaroxaban, dabigatran, edoxaban.

Question 8

What is the mechanism of action of DOACs?

Answer 8

Intervene directly in the coagulation cascade by inhibiting clotting factors such as factor Xa and thrombin, thus preventing formation of a clot.

Question 9

What is the mechanism of action of Warfarin?

Answer 9

Vitamin K antagonist. Prevents the production of vitamin-K dependent clotting factors by blocking epoxide reductase complex in the liver, thus inhibiting vitamin K activation.

Question 10

What is INR?

Answer 10

Prothrombin time i.e., measure of how long it takes the blood to clot.

Question 11

What is the ideal INR?

Answer 11

2-3

Question 12

What can be done to reverse an INR which is too high?

Answer 12

Give patient vitamin K.

Question 13

What are some common side effects of warfarin?

Answer 13

Bleeding, bruising, heavier/longer periods, rash, and mild hair loss.

Question 14

What are some red flag side effects of warfarin?

Answer 14

Blood in urine/vomit/sputum/stools, extremely large/dark or unexplained bruises, uncontrolled bleeding, jaundice, skin necrosis.

Question 15

How should a patient be switched from warfarin to a DOAC?

Answer 15

Stop warfarin and take INR. DOAC can be started when INR is less than 2.

Question 16

How should a patient be switched from a DOAC to warfarin?

Answer 16

Start warfarin and continue DOAC for 2 days measuring INR. When INR is in range, stop DOAC.

Question 17

What does a thromboprophylaxis risk assessment cover?

Answer 17

All patients admitted to hospital undergo this risk assessment. It assesses mobility, thrombosis risk, and bleeding risk.

Question 18

How should warfarin be dealt with before surgery?

Answer 18

Stop 3-5 days prior and give vitamin K the day before to ensure INR is less than 1.5. Patients at high risk of clots can have bridging with a LMWH between stopping warfarin and 24 hours before surgery.

Question 19

When can warfarin be restarted after surgery?

Answer 19

If hemostasis adequate, resume at normal maintenance dose on evening of surgery or next day.