1. Atrial Fibrillation and Anticoagulation
Dr Mark Merrick GP
Hannage Brook Medical Centre
Wirksworth
Meeting funded by Bayer HealthCare
L.GB.MKT July 2015
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3. Prevalence of AF

4. Stroke in AF
Patients with AF have a five-fold higher stroke risk than those without AF
AF doubles the risk of stroke when adjusted for other risk factors
Without preventive treatment, each year approximately 1 in 20 patients (5%) with AF will have a stroke
It is estimated that 15% of all strokes are caused by AF and that 12,500 strokes per year in England are directly attributable to AF

6. AF strokes are severe strokes
20% are fatal
60% are disabling
Compared to non AF strokes:-
70% increased hospital mortality
40% decrease in chance of discharge home
20% increase length of hospital stay

7. Risk reduction with warfarin
Reduces relative risk of stroke by approx 65 %
Absolute risk reduction:-
Primary stroke %
Secondary stroke %
Numbers needed to treat for 1 year to prevent 1 stroke:-
Primary stroke 37
Secondary stroke 12
Overall (approx)

8. NOACS
Studies show to be at least as effective and probably more effective than
Warfarin at stroke reduction in AF

9. Days since randomization
ROCKET AF – Primary efficacy endpoint
Stroke or systemic embolism
120
240
480
600
720 1 2 3 4 5 6
840
360
Cumulative event rate (%)
Warfarin
Rivaroxaban
Days since randomization
Number of subjects at risk
Rivaroxaban▼ 6958
Warfarin 7004

11. ASPIRIN There is no role for aspirin in the treatment of AF
It may be used in conjunction with an anticoagulant if there is coexisting
vascular disease eg MI, PAD

12. CHA2D2S2 VASC ITEM SCORE Congestive Heart Failure or Left
Ventricular Dysfunction 1
Hypertension 1
Age >/=
Diabetes
Stroke/TIA
Vascular disease (MI, PAD) 1
Age (65-74)
Sex category (female) 1

13. CHA2D2S2 VASC Score Annual Stroke Rate%
1 2% % % % % % % %

15. HAS-BLED SCORE

16. NICE June 2014
Anticoagulation may be with apixaban, dabigatran, rivaroxaban or a vitamin K antagonist
Discuss the options for anticoagulation with each patient and base the choice on their clinical features and preferences

17. Which Anticoagulant?

18. Warfarin- Pros Warfarin has been prescribed for more than 50 years.
Warfarin remains an established and cost effective option for anticoagulation in patients.
Can be used in valve disease including valve replacement.
INR gives clinicians a guide to patient compliance.
Effective and familiar use of antidote with vitamin K should a severe bleed occur whilst being treated.
Clearance of warfarin is not affected by renal function.
For patients with poor adherence, long half life may be advantageous

19. Warfarin - Cons
Warfarin - time to peak effect ranges from 3-5 days and a half-life averaging 40 hours.
Warfarin is known to interact with many food and drugs
Patients may have difficulty around complying with or accessing INR monitoring
Narrow therapeutic range
Poor INR control associated with increased morbidity and mortality

20. NICE Guideline for AF (June 2014)
Review TTR at each visit (exclude 1st 6 weeks and must be over a period of ≥ /12):
Reassess if over the past 6 months:
x2 INRs > 5 or x1 INR > 8 or x2 INRs < 1.5
TTR < 65%
Try to correct and take into account reasons for poor control:
Cognitive function
Adherence
Illness
Interacting drug Rx
Lifestyle inc.diet and EtOH
If cannot be improved consider other strategies

21. NOACS - PROS As well tolerated as warfarin
No food and minimal drug interactions
Predictable anticoagulant response (no A/C monitoring)
Fixed dosing
As or more effective than warfarin
Rapid onset and offset of action

22. NOAC - CONS
Short half life – missed does means inadequate anticoagulation
Cost
Renal function determines dose. Not suitable for severe renal impairment.
Does require baseline tests and ongoing monitorring
Not suitable for valvular AF
No known antidote

23. Bleed risks of NOACs NOACS all have lower risk of Intracranial Bleeds
Warfarin has slightly lower GI bleed risk than Rivaroxaban and Dabigatran (trials use different criteria so no head to head data)
GI bleeds on NOACS seem less severe

24. Renal Function and NOACS
All NOACs are a reasonable choice in mild to moderate CKD
Estimated Creatinine Clearance should be calculated to determine dose.
Cockroft-Gault equation uses age ,weight and serum creatinine)
CrCl> 50 ml/min: No dosing adjustments required
CrCl30-50 ml/min: use lower dose
CrCl15-30 ml/min: do not use dabigatran

25. Safe Prescribing of NOACs
Counselling the importance of strict adherence to therapy is the most crucial aspect of NOAC Rx (reinforce at every FU)
Routine monitoring:
Hb and liver function (annually)
Renal function:
Annually for CKD stage I–II (CrCl≥60 ml/min)
6 monthly for CKD stage III (CrCl30–60 ml/min)
3 monthly for CKD stage IV (CrCl≤30 ml/min)
Regular (3 monthly) follow up:
Counselling
Side effects
Medication review (interactions)

26. Drug Interactions Verapamil (use lower dose dabigatran) Amiodarone
Dronedarone
“Azole” antifungals
HIV protease inhibitors
Rifampicin, St John’s wort and phenytoin
(drugs that affect CYP and P450)

27. Switching
Warfarin to a NOAC:
INR < 2.0: start NOAC immediately
INR : start NOAC the next day
NOAC to warfarin:
Initiate warfarin with NOAC concomitantly until INR ≥ 2
Re-test INR 24hrs after NOAC discontinuation
Missed doses:
pt should take forgotten dose up till 6h (if bd NOAC) or 12h (if od NOAC) after scheduled intake
otherwise skip dose and take next dose as scheduled

28. Hannage Brook AF Audit 11/14
- Practice size
- Number on AF register 207
- Score of 2 or more
but no anticoagulation 63
Score of 1 (no anticoag) 8
Score 2 or more on aspirin 40
Score 1 on aspirin 4

29. Nottingham City CCG: The Huge opportunity in Af
750 AF patients undiagnosed
•In addition, use of CHA2DS2-Vasc instead of CHADS2and reducing exception reporting for anticoagulation to less than 15%, a further 2000high risk AF patients could be anticoagulated
This will likely result in:
56 fewer strokes per year
19 fewer deaths per year
£660,000 reduction in AF stroke related hospital admission costs per year

30. Discussion Choosing which anticoagulant Fear of new drugs
Patients worried re change (esp if on aspirin)
Worried not having INR
Compliance
Medidose
Domiciliary patients
GP-Pharmacy communication