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Thrombosis Update Tom DeLoughery MD FACP FAWM Oregon Health and Sciences University
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DISCLOSURE Current Relevant Financial Relationship(s) Speaker Bureau – None
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What I am Talking About Antiplatelet agents Antithrombotics Atrial fibrillation Venous thrombosis
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Anticoagulation Patients with hematological malignancies not immune to thrombosis DVT 3-5% –Line – 3-15% PICC > Central Coronary artery disease: –45-64: 5% – > 65: > 15%
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Issues Antiplatelet agents Antithrombotic –Atrial fibrillation –Valves –Venous thrombosis
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Antiplatelet Agents Increase risk of bleeding with counts < 50,000/ul –Hemophilia studies –Massive bleeding studies
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MI: Primary and Secondary Prevention Primary prevention –Minimal short term effect –Halt aspirin for duration Secondary prevention –22% reduction in new events –Stop and restart at 50,000/ul
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Coronary Stents Stent thrombosis devastating –30-50% fatal MI Highest Risk –Placed for AMI –Bare metal – 4 weeks –Drug eluting – 12 months Dual antiplatelet therapy for high risk period
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Drug Eluting Stents Drugs inhibits restenosis by inhibiting cell proliferation Inhibits endothelialization of stent Increasing reports of late thrombosis even 18 months
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Stent Management Outside “risk period” –Bare Metal > 4 weeks –Drug eluting > 12 months Aspirin until platelets < 20,000/uL
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Stent Management Risk Period –Bare metal < 4 weeks –Drug eluting < 12 months Cardiology input Continue dual antiplatelet therapy unless severe bleeding
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Acute Coronary Syndrome Aspirin beneficial even with severe thrombocytopenia Further therapy guided by catheterization –Angioplasty with no stenting –Short course of heparin
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Antithrombotic Therapy UF Heparin –Short T 1/2 0.5-1 hours LMWH –Longer T 1/2 4 hours –Reversible by protamine –Need to adjust for renal disease Fondaparinux –Longest T 1/2 17-19 hours –Not reversible by protamine –Contraindicated in renal failure
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General LMWH Plan Change warfarin patients to LMWH Continue full dose until platelets <50,000/uL “Prophylactic” dose until platelet <20,000/uL –Enoxaparin 40mg/day –Several studies have shown this dose effective for treatment
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Dabigatran Oral Thrombin Inhibitor Bioavailability: 6.5% Onset of action: 2-3 hours Half-life : 12-14 hours Renal excretion: 80% Drug interactions: p-glycoprotein
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Dabigatran: Bottom Line Superior to warfarin in stroke prevention GI side effects 15% 1.3x increase risk of MI – outweighed by benefit CrCl > 50 Effects aPTT
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Drug Interactions Contraindicated –Dronedarone, azoles, rifampin, St John’s wort, carbamazepine Caution with renal disease or use of multiple of these drugs –Verapamil, amiodarone, quinidine, clarithromycin
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Rivaroxaban Oral Xa Inhibitor Bioavailability: 80-100% Onset of action: 2.5-4 hours Half-life : 5-9 hours Renal excretion: ~66% Drug interactions: CYP 3A4
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Rivaroxaban Approved 10mg daily for DVT prophylaxis in TKR and THR Approved 20mg daily for afib –15mg if CrCl 15-50mL/m –Contraindicated < 15mL/m Approved for DVT –15mg BID x 3 weeks –20mg daily
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Drug interactions Ketoconazole, itraconazole, lopinavir/ritonavir, ritonavir, indinavir/ritonavir, and conivaptan Potential with renal insufficiency –CSA, Erythromycin, azithromycin, diltiazem, verapamil, quinidine, ranolazine, dronedarone, amiodarone, and felodipine
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Rivaroxaban: Bottom Line Effective in stroke prevention Superior in prevention of VTE Safer in treatment of VTE CrCl > 15 (15mg < 50) Once a day drug –BID x 3 weeks in acute VTE INR to monitor
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Apixaban Oral Xa Inhibitor Bioavailability: 66% Onset of action: 1-3 hours Half-life : 8-15 hours Renal excretion: 25% Drug interactions: CYP 3A4 –Multiple other pathways
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Drug interactions Ketoconazole, itraconazole, clarithromycin, lopinavir/ritonavir, ritonavir, indinavir/ritonavir, and conivaptan –Cut to 2.5 mg BID Avoid due to decrease effect –Carbamazepine, phenytoin, rifampin, St. John’s wort
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Apixaban: Bottom Line Superior in stroke prevention with less bleeding Superior in prevention of VTE Safer in therapy of VTE BID drug CrCl > 15 Does not effect INR/PTT
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Comparing Trials
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Atrial Fibrillation DrugStrokeBleeding ApixabanBetterSafer DabigatranBetterEqual RivaroxabanEqual Warfarin: $4/month + monitoring ($20-50/visit) Apixaban: $320/month Dabigatran: $235/month Rivaroxaban: $247/month
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ICH – Atrial Fibrillation StrokeIntracranial Hemorrhage Events/ 100 years RREvents/ 100 years RR Dabigatran 110 1.530.91 (0.74-1.11))0.230.31 (0.20-0.47) Dabigatran 150 1.110.66 (0.53-0.82)0.300.40 (0.27-0.60) Rivaroxaban1.760.79 (0.66-0.96)0.490.67 (0.47-0.94) Apixaban1.190.79 (0.65-0.95)0.330.42 (0.30-0.58) Potential for 10-12,000 less ICH in USA
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Atrial Fibrillation Dabigatran –Robust trial data for all CHADS2 Apixaban –More effective than warfarin –Better in patients at risk for bleeding –Safer – “the sweet spot” Rivaroxaban –Effective
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Venous Thrombosis DrugThrombosisBleeding ApixabanEqualSafer DabigatranEqual RivaroxabanEqualSafer Warfarin: $4/month + monitoring ($20-50/visit) LMWH: $100-120/day Apixaban: $320/month Rivaroxaban: $247/month Dabigatran: $235/month
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Venous Thrombosis Rivaroxaban – FDA approved –Cost effective for acute DVT –Safer Dabigatran with robust data –Two trials and extended therapy Apixaban –Effective and safer DVT treatment
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Reversal Drugs we have no antidote for: –Low molecular weight heparin, fondaparinux, aspirin, clopidogrel, ticagrelor, prasugrel, dabigatran, rivaroxaban, apixaban
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What We Do Life or limb threatening bleeding 50 units/kg of 4 factor PCC (kcentra)
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Atrial Fibrillation Leading indications for warfarin anticoagulation Warfarin reduced risk of stroke from 5%/yr to 1%/yr Risk predicated by CHADS2 score
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CHADS2 CHADS2 Score Stroke/yrRisk Level 01.9Low 12.8Low/moderate 24.0Moderate 35.9Moderate 48.5High 512.5High 618.2High
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Management CHAD2 <1: nothing >1: LMWH protocol or new anticoagulant Highest risk –Previous stroke –CHADS2>4 –Cardiac thrombus
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Cardiac Valves Bioprosthetic –Asprin until platelets < 50,000/uL Mechanical –New drugs absolutely contraindicated!!! –Aortic bileaflet – LMWH protocol –Higher risk Monitored LMWH Continue until platelets < 30,000/uL –Prophylactic throughout
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Venous Thrombosis On anticoagulants > 3 months since thrombosis –Hold anticoagulation –Prophylaxis < 3 months since thrombosis –LMWH protocol
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New Thrombosis Calf vein/Muscular vein –Thrombocytopenic Doppler 3 days and then weekly until resolved or 4 weeks –Not thrombocytopenia Muscular – 10 days Calf – 6 weeks
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Proximal Vein/PE New proximal thrombosis –IVC filter controversial Yes if extensive leg DVT Can be nidus for thrombosis Pulmonary embolism –Filter if leg thrombosis
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Prophylaxis? Range of DVT is 1.2-5.8% Would mandate prophylaxis in other situations! Stockings? Pharmacologic?
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Upper Extremity DVT No RCT Lower incidence of –PE –Recurrence –Recannulization –Thrombophilia Higher incidence of –Underlying vascular lesions
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Catheter Related DVT Common with PICCs –Less with tunneled catheters High risk of thrombosis –3-8% symptomatic –20-50% asymptomatic No benefit of prophylaxis
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Catheter Related DVT Therapy: High rates of bleeding! –By definition PICC placed in sick patients –RCT 4% incidence life threatening bleeding –OHSU 25% halted due to bleeding
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Catheter Related DVT Increasing interest in conservative approach –NeuroICU study > 75% no anticoagulation –OHSU – anticoagulation made no difference in outcomes –NCCN No anticoagulation if at risk for bleeding
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Catheter Related DVT Suggested approach –Pull line –No new one for 10 days –Consider anticoagulation if Patient very symptomatic No bleeding risk factors
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What I Talked About Antiplatelet agents Antithrombotics Atrial fibrillation Venous thrombosis
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