antiplatelets and anticoagulants

Question 1

What classess of antiplatelets are there? examples from each?

Answer 1

COX-1 inhibitor
- aspirin

PY12 inhibitor
- clopidogrel
- ticagrelor
- ticopidine
- prasugrel

Phosphodiesterase inhibitor
- dipyridamole
- cilostazol

Question 2

common side effect aspirin

Answer 2

dyspepsia, hameorrhage

Question 3

how to prevent a common adverse effect aspirin

Answer 3

prescribe PPI if risk of gastric complications eg >65, previous peptic ulcer disease, comorbidities, taking other gastric damaging drugs eg NSAIDs and steroids

Question 4

contraindications to aspirin

Answer 4

children under 16 (risk of reyes syndrome- brain swelling and liver damage), allergy to aspirin or another NSAID, avoid in 3rd trimester as prostaglandin inhibition may prematurely close ductus arteriosus,

Question 5

medical

Answer 5

ischemic stroke 300 mg for 2 weeks then 75mg

75mg clopidogrel for secondary prevention of isc stroke

Question 6

dose aspirin ACS

Answer 6

300mg once-only dose then 75 mg daily

Question 7

what class of drug is clopidogrel

Answer 7

P2Y12 inhibitor

Question 8

what class of drug is ticagrelor

Answer 8

P2Y12 inhibitor

Question 9

what class is prasugrel

Answer 9

P2Y12 inhibitor

Question 10

what is your DOAC of choice for PSA

Answer 10

rivaroxaban

Question 11

what is your LMWH of choice for PSA

Answer 11

enoxaparin

Question 12

what classes of antiplatelets are there

Answer 12

Direct
Factor Xa inhibitors
- rivaroxaban
- apixaban
- edoxaban
Thrombin inhibitors
- dabigatran

Indirect:
Vitamin K antagonist (oral)
- warfarin
Heparin
- UFH
- LMWH
Fondaparinux

Question 13

interpretation of wells score for PE

Answer 13

PE likely - more than 4 points
1. arranage immediate CTPA
+ if delay in CTPA, interim therapeutic anticoagulation = direct oral anticoagulant (DOAC) such as apixaban or rivaroxaban

if the CTPA is positive then a PE is diagnosed
if the CTPA is negative then consider a proximal leg vein ultrasound scan if DVT is suspected

PE unlikely - 4 points or less
1. d-dimer
2. if +ve –> CTPA and interim therapeutic anticoagualtion if delay

Question 14

ECG changes PE

Answer 14

most common = sinus tachycardia

classical = ‘S1Q3T3’ a large S wave in lead I, a large Q wave in lead III and an inverted T wave in lead III

Question 15

what other invetsigation shoult pts with ?PE get?

Answer 15

a chest x-ray is recommended for all patients to exclude other pathology
however, it is typically normal in PE
possible findings include a wedge-shaped opacification

Question 16

First line anticoagulant therapy for PE

Answer 16

RIVAROXABAN or apixaban

Question 17

Second line treatment for PE if DOAC CI

Answer 17

LMWH followed by dabigatran or edoxaban OR LMWH followed by a vitamin K antagonist (VKA, i.e. warfarin)

Question 18

Management of PE if severe renal impairment eg egfr <15/min

Answer 18

LMWH, unfractionated heparin or LMWH followed by a VKA

Question 19

Management of PE in antiphospholipid syndrome

Answer 19

LMWH followed by a VKA should be used

Question 20

length of anticoagulation for PE

Answer 20

provoked = 3 months

active cancer = 3-6 months

unprovoked = 6 months

Question 21

Management of PE with haemodynamic instability ie circulatory failure (e.g. hypotension)

Answer 21

thrombolysis

Question 22

what score should you calculate if DVT is a ddx

Answer 22

Two-level DVT Wells score

DVT likely: 2 points or more
DVT unlikely: 1 point or less

Question 23

how many points is ‘likely’ for dvt on two level wells score? management

Answer 23

2 or more
1. a proximal leg vein ultrasound scan should be carried out within 4 hours
- if +ve = start anticoagulant
- if -ve = a D-dimer test should be arranged. A negative scan and negative D-dimer makes the diagnosis unlikely and alternative diagnoses should be considered

2. If proximal leg vein ultrasound cannot be performed within 4 hours then a D-dimer test should be performed and interim therapeutic anticoagulation administered whilst waiting for the proximal leg vein ultrasound scan (which should be performed within 24 hours)
   - rivaroxaban or apixaban

• if the scan is negative but the D-dimer is positive:
  stop interim therapeutic anticoagulation
  offer a repeat proximal leg vein ultrasound scan 6 to 8 days later

Question 24

how many points is ‘unlikely’ for dvt on two level wells score? management?

Answer 24

1. perform a D-dimer test
   - this should be done within 4 hours. If not, interim therapeutic anticoagulation should be given until the result is available

if the result is positive then a proximal leg vein ultrasound scan should be carried out within 4 hours
if a proximal leg vein ultrasound scan cannot be carried out within 4 hours interim therapeutic anticoagulation should be administered whilst waiting for the proximal leg vein ultrasound scan

if the result is negative then DVT is unlikely and alternative diagnoses should be considered

Question 25

How long should anticoagulation be continued DVT

Answer 25

provoked - 3 months

active cancer - 3-6 months

unprovoked - 6 months

Question 26

define provoked dvt

Answer 26

due to an obvious precipitating event
e.g. immobilisation following major surgery.

The implication is that this event was transient and the patient is no longer at increased risk

Question 27

what score should be used to assess bleeding risk anticoagulation

Answer 27

ORBIT score