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Low Molecular Weight Heparin as bridging anticoagulant early after mechanical heart valve replacement. P Meurin, JY Tabet, A Ben Driss, H Weber, N Renaud Les Grands Prés. No conflict of interest. Which heparin should we use early after mechanical prosthetic valve replacement ?.

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  1. Low Molecular Weight Heparin as bridging anticoagulant early after mechanical heart valve replacement.P Meurin, JY Tabet, A Ben Driss, H Weber, N RenaudLes Grands Prés

  2. No conflict of interest

  3. Which heparin should we use early after mechanical prosthetic valve replacement ?

  4. ACC/AHA guidelines1 The use of heparin early after prosthetic valve replacement before warfarin achieves therapeutic levels is controversial  » • « It is important to note that thromboembolic • risk is increased early after insertion of the • prosthetic valve. (1) Bonow RO, Carabello B, de Leon AC et al. ACC/AHA guidelines for the management of patients with valvular heart disease : a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Patients with Valvular Heart Disease) . J Am Coll Cardiol. 1998; 32 : 1486-1588.

  5. ACCP Guidelines « We suggest administration of UH or LMWH until the INR is stable and at therapeutic levels for 2 consecutive days 2» Grade 2C (2)Salem DN, Dtein PD, Al-Ahmad A et al. Antithrombotic therapy in valvular heart disease-native and prosthetic. The Seventh Conference on Antithrombotic and Thrombolytic Therapy. CHEST 2004; 126 : 457S-482S.

  6. In the real world, • Heparin (UH or LMWH) is constantly used before Vitamin K Antagonist treatment achieves therapeutic level • after IV line ablation • bridge between intravenous Unfractionated Heparin (UH) withdrawal and the time when oral anticoagulation is fully effective : • LMWH or UH ?

  7. Medico-legal paradox in the choice of the heparin (LMWH or UH)

  8. According to the law LMWH have no autorisation in this indication According to the science Compared with UH, LMWH are : As efficient Safer More convenient In the literature, LMWH Have more evidence of efficiency than (at least subcutaneous) UH Medico-legal paradox

  9. In the early period after MeHVR, a first pilot study with LMWH3. • Montalescot study3 : • comparison of enoxaparin (n = 102) and calciparin (n = 106) after MeHV replacement • Follow up : 2 weeks : same number of thromboembolic and haemorragic events in the two groups LMWH UH day 2 (3)Montalescot G, et al.Circulation 2001; 101 : 1083-86.

  10. 5 years later : not much additional data4 (4) Fanikos J, et al. Am J Cardiol 2004; 93 : 247-50. But as a pilot study, it had some flaws : • Retrospective design • Small number of patients receiving a LMWH • n = 102 • Small number of patients having undergone a mitral valve replacement (n = 10) • Short follow up (2 weeks) And the author conclude in pointing out « the need for collection of more clinical data and for randomized trials »

  11. Aim of the study • Evaluate the feasibility of an LMWH in this indication : • In a prospective study • In a larger population • With a longer follow-up • With a higher number of Mitral Valve Replacement Patients

  12. design • Prospective monocentric study • Selection : • All consecutive patients (from January 2000 to January 2005) in whom MeHVR had been recently performed and transferred to our Post Operative Cardiac Rehabilitation Center (POCRC) • Exclusion : • VKA treatment already begun and target INR achieved • Renal insufficiency (creatininemia <150μm/l), heparin induced thrombocytopenia, pregnancy. • Follow-up : 3 months after LMWH withdrawal

  13. Target INR Operation POCRC arrival LMWH UH VKA Day 0 VKA Anticoagulation management • Monitoring : • INR three times a week • Platelet count twice a week • Anti Xa activity in : • Obese patients (BMI >30) • LMWH : Enoxaparin : 100 iu/kg bid

  14. Results

  15. Patients • Selected : n = 695 • Excluded : n = 445 : • VKA treament already fully effective : 425 • MVR and DVR : 2.5-3.5 • AVR : 2-3 • Creatininemia >150 : n = 16 • Suspected HIT : n = 4

  16. Patients Included : n = 250 • VKA treatment : • -started before inclusion • n = 190 • INR = 1.5± 0.4 -started at inclusion • n = 60 16 ± 11 days after surgery

  17. Mean age 60 ± 11 Men 60 % LVEF 57 ± 7 % LVEDD 50 ± 7 mm LAD 45 ± mm Mean trans aortic gradient(n = 216) 13 ± 5 mm Hg Mean transmitral gradient(n = 60) 4 ± 1.5 mmHg AVR (n = 190) AVR alone 128 AVR + CABG 31 AVR + Bentall 29 AVR + Bentall + CABG 2 MVR (n = 34) MVR alone 21 MVR + TV 8 MVR + CABG 5 DVR (n = 26) DVR alone 21 DVR + CABG 3 DVR + Bentall 1 DVR + TV 1 Patients Characteristics (n= 250)

  18. Thromboembolic risk factors • Age > 70 20.4 % • Hypertension 40% • LVEF < 45 % 11.6 % • Prior ischemic stroke, 12.4 % • Atrial fibrillation 50 % • Enlarged LA (LAD > 45 mm) 53.2 % • Redo cardiac Surgery 19% • Diabetes 13% • MVR 13.6% • DVR 10.4 % • 90 % of the patients had at least one risk factor, 61% two and 24 % three or more

  19. Comments • High risk population • 90 % of the patients had at least one risk factor, 61% two and 24 % three or more • 250 (out of 695 patients selected) in whom VKA treatment was not fully effective 16 ± 11 days after surgery • Mostly because of post operative complications (pericardial effusion monitoring, pace-maker implantation…)

  20. Results : clinical outcomes

  21. Prospective intra POCRC follow-up : 20 ± 7 days after LMWH beginning • Thromboembolic events :n = 0 • Haemorragic events • Major : n = 2 • 1 tamponade • 1 abdominal muscle haematoma requiring blood transfusion • Minor :n = 3

  22. 3 months follow-up • N = 247 (98.8 %) • 1 transient ischaemic attack • Normal transoesophagal echocardiography • 70 % carotid stenosis

  23. Conclusion : in patients having recently undergone a mechanical heart valve replacement • A LMWH therapy as a bridge • From immediate post operative UH cessation • To the time when oral anticoagulation is fully effective seems efficient and safe in preventing thromboembolic events. • A randomized study comparing LMWH to UH in this indication is warranted

  24. Finally : when could we use LMWH after mechanical heart valve replacement ? • 1°) Immediately after surgery : • Montalescot study • 2°) Temporary interruption of VKA treatment • Eg for extracardiac surgery5.6 • 3°) Early post operative period after IV line withdrawal : • Our study 5. Kovacs MJ et al. Circulation 2004; 110: 1658-63 6. Douketis JD. Arch Intern Med 2004; 164(12): 1319-26.

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