Transcript Antithrombotic therapy in non-valvular AF patients

Rohan Subasinghe
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Non valvular aF increases with age from 0.5 %
at age 50-59 to 9 % at age 80-89
AF is an independent Risk factor for CVA
Patients with AF have a 5 fold mean increase
in Stroke due to atrial thrombosis.
Stroke mortality is higher in aptients with AF
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Aspirin - irreversibly blocks the formation of thromboxane A2
in platelets, producing an inhibitory effect on platelet
aggregation
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Warfarin - Warfarin inhibits the vitamin K-dependent
synthesis of biologically active forms of the calciumdependent clotting factors II, VII, IX and X
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ximelagatran - direct thrombin inhibitor – less monitoring
required but increased ALT levels
Risk stratification of patients –aspirin or
warfarin?
• Possibility of intra and extra cranial
haemorrhages.
• Interaction with other medications
• Disability, cognitive impairment, and problems
with compliance are common in the elderly
patients with AF
• Inconvenience of monitoring in warfarin therapy
and impact on quality of life
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http://www.nice.org.uk/nicemedia/pdf/CG036
quickrefguide.pdf
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Numerous RCTs support tnromboprophylaxis
in non valvular AF patients
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Meta-analysis: Antithrombotic Therapy to
Prevent Stroke in Patients Who Have
Nonvalvular Atrial Fibrillation Robert G.
Hart, MD; Lesly A. Pearce, MS; and Maria I.
Aguilar, MD
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To characterize the efficacy and safety of
antithrombotic agents for stroke prevention
in patients who have atrial fibrillation
Adding 13 recent randomized trials to a
previous meta-analysis.
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Double Blind Randomised trials
Mean follow-up of 3 months or longer that
tested
Antithrombotic agents in patients who have
nonvalvular atrial fibrillation.
Data Extraction: Two coauthors independently extracted
information regarding interventions; participants; and
occurrences of ischemic and hemorrhagic stroke, major
extracranial bleeding, and death.
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Twenty-nine trials included 28 044 participants
Mean age, 71 years; mean follow-up, 1.5 years).
Compared with the control, adjusted-dose warfarin (6 trials,
2900 participants) reduced stroke by 64% (95% CI, 49% to
74%) NNT 37 primary 12 secondary prev
Antiplatelet agents (8 trials, 4876 participants) reduced
stroke by 22% (CI, 6% to 35%). NNT 125 / 40
Adjusted-dose warfarin was substantially more efficacious
than antiplatelet therapy (relative risk reduction, 39% [CI,
22% to 52%]) (12 trials, 12 963 participants).
Heterogeneous NNT not calculable (estimated at 24)
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Other randomized comparisons were inconclusive.
Absolute increases in major extracranial haemorrhage were
small (0.3% per year) on the basis of metaanalysis.
NNH for major haemorrhage 250
NNT for mortality benefit 200
CVA
AF
Non-AF
30-day Mortality 23%
8%
30-day recurrent 1%
CVA
4%
Annual
recurrent CVA
8.2%
11%
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Bearing in mind that AF prevalence increases
with age – is a mean age of 71 in the trials
representative of patients we see?