To thin or not to thin?

Dr Sarah Wesley Cairns 2013

64yo CABG x3

• On pump, LIMA to LAD and SVG to OM1 and Cx

• PMHx: hypertension and hypercholesterolaemia

• What antiplatelet therapy and when?Aspirin

Aspirin + Clopidogrel Warfarin

64yo CABG x3

• Aspirin at 6h if bleeding not an issue and daily afterwards• 75-150mg optimal dose• Reduction in mortality/CVA/MI/AKI

AspirinAspirin +

Clopidogrel Warfarin

64yo CABG x3

• Are there any indications for dual (aspirin and clopidogrel) antiplatelet therapy?

64yo CABG x3

• Dual therapy • CABG post acute coronary syndrome • Stent in situ not bypassed by graft• Off-pump CABG• Not indicated specifically for SVG

• SVG 15% occlude in 1 year and 50% in 10 years

• CASCADE study 2008

• Clopidogrel and aspirin in SVG

• Showed no benefit in addition of clopidogrel

64yo CABG x3

• Clopidogrel acceptable alternative if allergic to aspirin• No data showing superior• Aspirin remains drug of choice in routine on-

pump CABG

64yo CABG x3

• He goes on to develop AF day 2 • 3 days later remains in rate controlled AF on

amiodarone

• Would you start any additional anticoagulation?

Clopidogreliv Heparin +

WarfarinNone

64yo CABG x3

• iv heparin and warfarin if remains in AF for > 48h• Aim INR 2-3• Double the risk of stroke with no

anticoagulation

• If reverts to sinus within 48h • Evidence equivocal for aspirin alone or adding

warfarin Clopidogrel

iv Heparin + Warfarin

None

Questions ?

72yo tissue AVR

• EF 45% with moderate LVH• Sinus rhythm• No previous DVT/PE• No post-operative complications

• What anticoagulation therapy should he have and when?

Clopidogrel Aspirin Warfarin

72yo tissue AVR

• No risk factors for VTE disease -> aspirin alone• Stroke rate of 0.2% for AVR in sinus

Clopidogrel Aspirin Warfarin

72yo tissue AVR

• Risk factors for VTE disease • AF, EF< 30-35%, hypercoagulable or previous

VTE

• Warfarin with INR 2-3

Clopidogrel Aspirin Warfarin

54yo Mechanical AVR

• What if he was 54 and his original operation was a mechanical AVR?• Normal coronary arteries• No risk factors for cardiovascular disease

Clopidogrel + Aspirin

Aspirin iv Heparin +

Warfarin

54yo Mechanical AVR

• Warfarin and iv heparin • Iv heparin continues till INR therapeutic for 2

days

• Intensity of warfarin relates to thrombogenicity of valve and risk factors for thrombus formation• INR 2.5 for low risk up to 3.5 for high risk

• Risk relates to • Type of valve• Risk factors for VTE disease

Mechanical AVR

• Warfarin alone or combination warfarin and anti-platelets?• Balance of thrombosis risk vs bleeding

Mechanical AVR

• Add aspirin to warfarin if risk factors for cardiovascular disease, stents, previous PE, high risk valve

• Many guidelines recommend adding aspirin unless concerns over bleeding• Significant reduction in thromboembolism

and all cause mortality 9 -> 4/5%• Increase in bleeding risk 5 -> 8%

63yo with mechanical MVR

• Second generation valve inserted• Past history of Atrial Fibrillation• EF 40%

• What anticoagulation therapy should she have and when?

MV repair or tissue MV

• What if she’d had a mitral valve repair or tissue valve rather than mechanical valve replacement and was in sinus rhythm?

MV repair or tissue MV

• 3 months warfarin or antiplatelets• No evidence either is superior• 20% of all thromboembolic events in first

month

Thrombosis rates

• Embolism or valve thrombosis with mechanical valve replacements • No anticoagulation

• Aortic valve 4-12% per year

• Mitral valve 10-22% per year

• AVR with anticoagulation• Warfarin 1% per patient per year

• Aspirin 2.2% per patient per year

• MVR and AVR with risk factors for VTE• 2% and 4.5% respectively

Questions?

Stopping anti-platelet agents

• Routine CABG stop anti-platelet drug 7 days pre-op

• NSTEMI/MI/Prior to PCI• Clear benefits for clopidogrel and aspirin

administration shown in many large RCT• Guidelines recommend stopping clopidogrel 5-

7 days before surgery if clinical condition allows• 1% increase in risk of MI during this time

Stopping Warfarin pre-op

• Low risk of thrombosis• Bileaflet mechanical AVR with no other risk factors

• Stop warfarin 3-5 days pre-op no heparin required

• High risk of thrombosis• Mechanical MVR/Mechanical AVR with risk factors

• Stop warfarin and start heparin when

INR < 2• Restart heparin as early after surgery as

as bleeding allows

What about newer oral antithrombotics?

• Direct thrombin inhibitor – Dabigatrin• RE-ALIGN study • vs warfarin in mechanical valves• Stopped early as increased risk of

CVA/MI/Thrombosis

• Factor Xa inhibitor - Rivaroxaban • Not studied and not recommended