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| '''Associate Editors-in-Chief:''' {{CZ}},[[User:Mohammed sbeih|Mohammed A. Sbeih, M.D.]] [mailto:msbeih@perfuse.org] | | '''Associate Editors-in-Chief:''' {{CZ}},[[User:Mohammed sbeih|Mohammed A. Sbeih, M.D.]] [mailto:msbeih@wikidoc.org] |
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| ==Perioperative medical therapy==
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| ===Aspirin===
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| Aspirin is a simple cost effective therapy that has been associated with improved clinical outcomes among patients undergoing CABG. The optimal timing of aspirin administration appears to be in the 48 hours immediately after CABG.<ref name="pmid3286040">{{cite journal |author=Goldman S, Copeland J, Moritz T, Henderson W, Zadina K, Ovitt T, Doherty J, Read R, Chesler E, Sako Y |title=Improvement in early saphenous vein graft patency after coronary artery bypass surgery with antiplatelet therapy: results of a Veterans Administration Cooperative Study |journal=[[Circulation]] |volume=77 |issue=6 |pages=1324–32 |year=1988 |month=June |pmid=3286040 |doi= |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=3286040 |issn= |accessdate=2010-07-22}}</ref><ref name="pmid2680158">{{cite journal |author=Goldman S, Copeland J, Moritz T, Henderson W, Zadina K, Ovitt T, Doherty J, Read R, Chesler E, Sako Y |title=Saphenous vein graft patency 1 year after coronary artery bypass surgery and effects of antiplatelet therapy. Results of a Veterans Administration Cooperative Study |journal=[[Circulation]] |volume=80 |issue=5 |pages=1190–7 |year=1989 |month=November |pmid=2680158 |doi= |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=2680158 |issn= |accessdate=2010-07-22}}</ref><ref name="pmid8124800">{{cite journal |author=Goldman S, Copeland J, Moritz T, Henderson W, Zadina K, Ovitt T, Kern KB, Sethi G, Sharma GV, Khuri S |title=Long-term graft patency (3 years) after coronary artery surgery. Effects of aspirin: results of a VA Cooperative study |journal=[[Circulation]] |volume=89 |issue=3 |pages=1138–43 |year=1994 |month=March |pmid=8124800 |doi= |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=8124800 |issn= |accessdate=2010-07-22}}</ref><ref name="pmid7045659">{{cite journal |author=Chesebro JH, Clements IP, Fuster V, Elveback LR, Smith HC, Bardsley WT, Frye RL, Holmes DR, Vlietstra RE, Pluth JR, Wallace RB, Puga FJ, Orszulak TA, Piehler JM, Schaff HV, Danielson GK |title=A platelet-inhibitor-drug trial in coronary-artery bypass operations: benefit of perioperative dipyridamole and aspirin therapy on early postoperative vein-graft patency |journal=[[N. Engl. J. Med.]] |volume=307 |issue=2 |pages=73–8 |year=1982 |month=July |pmid=7045659 |doi= |url= |issn= |accessdate=2010-07-22}}</ref><ref name="pmid6361561">{{cite journal |author=Chesebro JH, Fuster V, Elveback LR, Clements IP, Smith HC, Holmes DR, Bardsley WT, Pluth JR, Wallace RB, Puga FJ |title=Effect of dipyridamole and aspirin on late vein-graft patency after coronary bypass operations |journal=[[N. Engl. J. Med.]] |volume=310 |issue=4 |pages=209–14 |year=1984 |month=January |pmid=6361561 |doi= |url= |issn= |accessdate=2010-07-22}}</ref><ref name="pmid12397188">{{cite journal |author=Mangano DT |title=Aspirin and mortality from coronary bypass surgery |journal=[[N. Engl. J. Med.]] |volume=347 |issue=17 |pages=1309–17 |year=2002 |month=October |pmid=12397188 |doi=10.1056/NEJMoa020798 |url=http://content.nejm.org/cgi/pmidlookup?view=short&pmid=12397188&promo=ONFLNS19 |issn= |accessdate=2010-07-22}}</ref><ref name="pmid6144975">{{cite journal |author=Lorenz RL, Schacky CV, Weber M, ''et al.'' |title=Improved aortocoronary bypass patency by low-dose aspirin (100 mg daily). Effects on platelet aggregation and thromboxane formation |journal=Lancet |volume=1 |issue=8389 |pages=1261–4 |year=1984 |month=June |pmid=6144975 |doi= |url=}}</ref><ref name="pmid8377686">{{cite journal |author=Hockings BE, Ireland MA, Gotch-Martin KF, Taylor RR |title=Placebo-controlled trial of enteric coated aspirin in coronary bypass graft patients. Effect on graft patency |journal=Med. J. Aust. |volume=159 |issue=6 |pages=376–8 |year=1993 |month=September |pmid=8377686 |doi= |url=}}</ref> <ref name="pmid2203555">{{cite journal |author=Sanz G, Pajarón A, Alegría E, ''et al.'' |title=Prevention of early aortocoronary bypass occlusion by low-dose aspirin and dipyridamole. Grupo Español para el Seguimiento del Injerto Coronario (GESIC) |journal=Circulation |volume=82 |issue=3 |pages=765–73 |year=1990 |month=September |pmid=2203555 |doi= |url=}}</ref><ref name="pmid2022014">{{cite journal |author=Gavaghan TP, Gebski V, Baron DW |title=Immediate postoperative aspirin improves vein graft patency early and late after coronary artery bypass graft surgery. A placebo-controlled, randomized study |journal=Circulation |volume=83 |issue=5 |pages=1526–33 |year=1991 |month=May |pmid=2022014 |doi= |url=}}</ref><ref name="pmid6347428">{{cite journal |author=Sharma GV, Khuri SF, Josa M, Folland ED, Parisi AF |title=The effect of antiplatelet therapy on saphenous vein coronary artery bypass graft patency |journal=Circulation |volume=68 |issue=3 Pt 2 |pages=II218–21 |year=1983 |month=September |pmid=6347428 |doi= |url=}}</ref><ref name="pmid3874009">{{cite journal |author=Brown BG, Cukingnan RA, DeRouen T, ''et al.'' |title=Improved graft patency in patients treated with platelet-inhibiting therapy after coronary bypass surgery |journal=Circulation |volume=72 |issue=1 |pages=138–46 |year=1985 |month=July |pmid=3874009 |doi= |url=}}</ref><ref name="pmid7033673">{{cite journal |author=McEnany MT, Salzman EW, Mundth ED, ''et al.'' |title=The effect of antithrombotic therapy on patency rates of saphenous vein coronary artery bypass grafts |journal=J. Thorac. Cardiovasc. Surg. |volume=83 |issue=1 |pages=81–9 |year=1982 |month=January |pmid=7033673 |doi= |url=}}</ref><ref name="pmid2225410">{{cite journal |author=Goldman S, Copeland J, Moritz T, ''et al.'' |title=Internal mammary artery and saphenous vein graft patency. Effects of aspirin |journal=Circulation |volume=82 |issue=5 Suppl |pages=IV237–42 |year=1990 |month=November |pmid=2225410 |doi= |url=}}</ref>
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| Rigorous randomized trials have been required to document the benefits of aspirin, to determine the optimal timing of aspirin, and to overcome fears surrounding the risk of bleeding associated with administration of aspirin in the setting of CABG. There has been a hesitancy to recommend the administration of antiplatelet agents in the setting of CABG for several reasons:
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| *Platelet counts and platelet concentration are reduced during the peri-operative period as a result of sequestration and hemodilution<ref name="pmid1614220">{{cite journal |author=Khuri SF, Wolfe JA, Josa M, Axford TC, Szymanski I, Assousa S, Ragno G, Patel M, Silverman A, Park M |title=Hematologic changes during and after cardiopulmonary bypass and their relationship to the bleeding time and nonsurgical blood loss |journal=[[J. Thorac. Cardiovasc. Surg.]] |volume=104 |issue=1 |pages=94–107 |year=1992 |month=July |pmid=1614220 |doi= |url= |issn= |accessdate=2010-07-22}}</ref>
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| *Platelet function is impaired following CABG due to both hypothermia <ref name="pmid7359906">{{cite journal |author=Hessel EA, Schmer G, Dillard DH |title=Platelet kinetics during deep hypothermia |journal=[[J. Surg. Res.]] |volume=28 |issue=1 |pages=23–34 |year=1980 |month=January |pmid=7359906 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/0022-4804(80)90078-5 |issn= |accessdate=2010-07-22}}</ref> and/or mechanical filtering.<ref name="pmid7686785">{{cite journal |author=Kestin AS, Valeri CR, Khuri SF, Loscalzo J, Ellis PA, MacGregor H, Birjiniuk V, Ouimet H, Pasche B, Nelson MJ |title=The platelet function defect of cardiopulmonary bypass |journal=[[Blood]] |volume=82 |issue=1 |pages=107–17 |year=1993 |month=July |pmid=7686785 |doi= |url=http://www.bloodjournal.org/cgi/pmidlookup?view=long&pmid=7686785 |issn= |accessdate=2010-07-22}}</ref><ref name="pmid9527196">{{cite journal |author=Morse DS, Adams D, Magnani B |title=Platelet and neutrophil activation during cardiac surgical procedures: impact of cardiopulmonary bypass |journal=[[Ann. Thorac. Surg.]] |volume=65 |issue=3 |pages=691–5 |year=1998 |month=March |pmid=9527196 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/S0003-4975(97)01425-2 |issn= |accessdate=2010-07-22}}</ref><ref name="pmid1718190">{{cite journal |author=Rinder CS, Mathew JP, Rinder HM, Bonan J, Ault KA, Smith BR |title=Modulation of platelet surface adhesion receptors during cardiopulmonary bypass |journal=[[Anesthesiology]] |volume=75 |issue=4 |pages=563–70 |year=1991 |month=October |pmid=1718190 |doi= |url= |issn= |accessdate=2010-07-22}}</ref>
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| In so far as the focus of clinical care has at times been on reducing the risk of bleeding rather than on reducing the risk of thrombosis, there has likewise been a tendency to discontinue aspirin and reverse anticoagulant therapy before surgery, to administer platelet transfusions during surgery,<ref> Stover EP, Siegel LC, Parks R, et al. Variability in transfusion practice for coronary artery bypass surgery persists despite national consensus
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| guidelines: a 24-institution study. Anesthesiology 1998;88:327-33.</ref><ref>Spiess BD, Ley C, Body SC, et al. Hematocrit value on intensive care unit entry influences the frequency of Q-wave myocardial infarction after coronary artery bypass grafting. J Thorac Cardiovasc Surg 1998;116:460-7. and to administer prothrombotic agents(antifibrinolytic agents).</ref><ref>Eagle KA, Guyton RA, Davidoff R, et al. ACC/AHA guidelines for
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| coronary artery bypass graft surgery: a report of the American College of
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| Cardiology/American Heart Association Task Force on Practice Guidelines
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| (Committee to Revise the 1999 Guidelines for Coronary Artery Bypass
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| Graft Surgery). J Am Coll Cardiol 1999;34:1262-347.</ref> There is little randomized controlled data to support these practices adn non-randomized data suggest that these practices are associated with a significant increase in death and ischemic events.<ref name="pmid12397188">{{cite journal |author=Mangano DT |title=Aspirin and mortality from coronary bypass surgery |journal=[[N. Engl. J. Med.]] |volume=347 |issue=17 |pages=1309–17 |year=2002 |month=October |pmid=12397188 |doi=10.1056/NEJMoa020798 |url=http://content.nejm.org/cgi/pmidlookup?view=short&pmid=12397188&promo=ONFLNS19 |issn= |accessdate=2010-07-22}}</ref>
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| ====Benefit of early post-operative aspirin administration====
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| In one of the first studies in this field, Goldman et al compared the rate of SVG patency among CABG patients treated with a variety of antiplatelet regimens.<ref name="pmid3286040">{{cite journal |author=Goldman S, Copeland J, Moritz T, Henderson W, Zadina K, Ovitt T, Doherty J, Read R, Chesler E, Sako Y |title=Improvement in early saphenous vein graft patency after coronary artery bypass surgery with antiplatelet therapy: results of a Veterans Administration Cooperative Study |journal=[[Circulation]] |volume=77 |issue=6 |pages=1324–32 |year=1988 |month=June |pmid=3286040 |doi= |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=3286040 |issn= |accessdate=2010-07-22}}</ref> All therapies except aspirin were started 48 hours before CABG. When aspirin was part of the regime, one 325 mg dose was given 12 hours pre-operatively, and the assigned therapy was maintained thereafter.
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| The 60 day rates of angiographic patency (555 patients with 1,781 grafts) were:
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| *Aspirin, 325 mg daily: 93.5%
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| *Aspirin, 325 mg three times daily: 92.3%
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| *Aspirin plus dipyridamole (325 mg and 75 mg, respectively, three times daily): 91.9%
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| *Sulfinpyrazone (267 mg three times daily): 90.2%
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| *Placebo (three times daily): 85.2%
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|
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| (P<0.05 for all aspirin regimens vs placebo)
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| Aspirin was associated with a greater median chest tube drainage within the first 35 hours post-operatively compared with placebo (p<0.02):
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| *Aspirin daily (965 ml)
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| *Aspirin three times daily (1175 ml)
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| *Aspirin plus dipyridamole (1000 ml)
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| *Sulfinpyrazone (775 ml)
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| *Placebo (805 ml)
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| The rate of reoperation was higher (p<0.01) among patients treated with aspirin (6.5%) than among those patients not treated with aspirin (1.7%).
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| At one year of follow-up in the same cohort of patients (n=406 patients with 1,315 SVGs), the rate of SVG occlusion was 15.8% in all the aspirin groups combined vs 22.6% among those treated with placebo (p = 0.029).<ref name="pmid2680158">{{cite journal |author=Goldman S, Copeland J, Moritz T, Henderson W, Zadina K, Ovitt T, Doherty J, Read R, Chesler E, Sako Y |title=Saphenous vein graft patency 1 year after coronary artery bypass surgery and effects of antiplatelet therapy. Results of a Veterans Administration Cooperative Study |journal=[[Circulation]] |volume=80 |issue=5 |pages=1190–7 |year=1989 |month=November |pmid=2680158 |doi= |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=2680158 |issn= |accessdate=2010-07-22}}</ref> This benefit was signficant among those SVGs in which the target vessel was less than or equal to 2.0 mm in diameter (20.1% vs 32.3% for the placebo group (p = 0.008), while in those SVGs anastomosed to target vessels > 2.0 mm in diameter there was no difference in the rate of SVG occlusion (8.7% vs. 9.0%, p = 0.918).
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| While there were benefits in early patency and patency at one year in this cohort of patients, between years one and three, there was no benefit in the rate of occlusion. Among those SVGs that were patent at 1 year, the occlusion rate at 3 years was 4.8% for aspirin treated patients vs 4.2% for placebo treated patients (p=NS).<ref name="pmid8124800">{{cite journal |author=Goldman S, Copeland J, Moritz T, Henderson W, Zadina K, Ovitt T, Kern KB, Sethi G, Sharma GV, Khuri S |title=Long-term graft patency (3 years) after coronary artery surgery. Effects of aspirin: results of a VA Cooperative study |journal=[[Circulation]] |volume=89 |issue=3 |pages=1138–43 |year=1994 |month=March |pmid=8124800 |doi= |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=8124800 |issn= |accessdate=2010-07-22}}</ref>
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| The benefits of early antiplatelet therapy were also documented by Chesebro et al who performed a double blind randomized trial evaluating the benefit of dipyridamole (administered two days before operation) plus aspirin (added seven hours after operation) in 407 patients.<ref name="pmid7045659">{{cite journal |author=Chesebro JH, Clements IP, Fuster V, Elveback LR, Smith HC, Bardsley WT, Frye RL, Holmes DR, Vlietstra RE, Pluth JR, Wallace RB, Puga FJ, Orszulak TA, Piehler JM, Schaff HV, Danielson GK |title=A platelet-inhibitor-drug trial in coronary-artery bypass operations: benefit of perioperative dipyridamole and aspirin therapy on early postoperative vein-graft patency |journal=[[N. Engl. J. Med.]] |volume=307 |issue=2 |pages=73–8 |year=1982 |month=July |pmid=7045659 |doi= |url= |issn= |accessdate=2010-07-22}}</ref> At one month, the angiographic rate of SVG occlusion on a per lesion basis was 3% vs 10% of grafts, and on a per patient basis the rate of having at least one SVG occluded was 8% vs 21% for treated vs untreated patients respectively. Likewise, at one year, the angiographic rate of SVG occlusion on a per lesion basis was 11% vs 25% of grafts, and on a per patient basis the rate of having at least one SVG occluded was 22% vs 47% for treated vs untreated patients respectively.<ref name="pmid6361561">{{cite journal |author=Chesebro JH, Fuster V, Elveback LR, Clements IP, Smith HC, Holmes DR, Bardsley WT, Pluth JR, Wallace RB, Puga FJ |title=Effect of dipyridamole and aspirin on late vein-graft patency after coronary bypass operations |journal=[[N. Engl. J. Med.]] |volume=310 |issue=4 |pages=209–14 |year=1984 |month=January |pmid=6361561 |doi= |url= |issn= |accessdate=2010-07-22}}</ref>
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| In a non-randomized retrospective analysis of 7,500 variables, Mangano et al evaluated the relationship between early aspirin use and clinical outcomes in 5,065 patients at 70 centers in 17 countries.<ref name="pmid12397188">{{cite journal |author=Mangano DT |title=Aspirin and mortality from coronary bypass surgery |journal=[[N. Engl. J. Med.]] |volume=347 |issue=17 |pages=1309–17 |year=2002 |month=October |pmid=12397188 |doi=10.1056/NEJMoa020798 |url=http://content.nejm.org/cgi/pmidlookup?view=short&pmid=12397188&promo=ONFLNS19 |issn= |accessdate=2010-07-22}}</ref> Mortality was 1.3% among those patients treated with aspirin in the first 48 hours after CABG vs 4.0% among those who were not treated with aspirin (p<0.001). Likewise, aspirin therapy reduced the risk of MI from 5.4% to 2.8% (p<0.001), the risk of stroke from 2.6% to 1.3% (p=0.01), the risk of bowel infarction from 0.8% to 0.3% (p=0.01) and the risk of renal failure from 3.4% to 0.9%, p<0.001). Aspirin treatment was not associated with an increased risk of hemorrhage or impaired wound healing.
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| ====Pre-Operative vs Post-Operative Administration of Aspirin====
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| Although the aforementioned studies demonstrated improved early and late patency with the pre-opeartive administration of aspirin, there was a higher rate of bleeding. Goldman et al conduted a prospective, randomized, double-blind, placebo-controlled trial to compare the safety and effectiveness of 325 mg of aspirin therapy initiated either the night before before CABG vs aspirin initiated via nasogastric tube 6 hours post-operatively.<ref name="pmid1860197">{{cite journal |author=Goldman S, Copeland J, Moritz T, Henderson W, Zadina K, Ovitt T, Kern KB, Sethi G, Sharma GV, Khuri S |title=Starting aspirin therapy after operation. Effects on early graft patency. Department of Veterans Affairs Cooperative Study Group |journal=[[Circulation]] |volume=84 |issue=2 |pages=520–6 |year=1991 |month=August |pmid=1860197 |doi= |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=1860197 |issn= |accessdate=2010-07-22}}</ref> The rate of saphenous vein graft occlusion rate was 7.4% vs 7.8% for pre vs post-operative aspirin administration. Pre-operative aspirin was associated with a greater amount of blood volume transfused (900 versus 725 cc, p = 0.006), greater chest tube drainage at 6 hours (500 vs 448 cc, p=0.011) and a higher rate of re-operation for bleeding (6.3% vs 2.4%, p = 0.036).
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| ===Post-operative clopidogrel===
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| There are no randomized controlled trials that demonstrate a benefit of clopidogrel in the post-operative management of CABG patients.<ref name="pmid19539077">{{cite journal |author=Patel JH, Stoner JA, Owora A, Mathew ST, Thadani U |title=Evidence for using clopidogrel alone or in addition to aspirin in post coronary artery bypass surgery patients |journal=[[Am. J. Cardiol.]] |volume=103 |issue=12 |pages=1687–93 |year=2009 |month=June |pmid=19539077 |doi=10.1016/j.amjcard.2009.02.021 |url=http://linkinghub.elsevier.com/retrieve/pii/S0002-9149(09)00603-1 |issn= |accessdate=2010-07-22}}</ref> Furthermore, retrospective subgroup analyses from large trials of acute coronary syndrome patients (1 trial) and stable coronary artery disease patients (3 trials) have not demonstrated a benefit of post-operative clopidogrel. They did, however, demonstrate a trend toward an increased risk of major and minor bleeding with the combined use of clopidogrel plus aspirin.
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| ==Percutaneous coronary intervention (PCI) to treat saphenous vein graft failure==
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| There are many different choices to consider when deciding the most appropriate treatment for [[SVG]] [[stenosis]], including [[PTCA]], [[PCI]] with [[bare metal stent|bare metal]] or [[drug-eluting stents]], [[PCI]] with covered [[stents]], embolic protection devices, [[debulking]]/[[thrombus]] removal, and surgical [[revascularization]].
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| ===Percutaneous transluminal coronary angioplasty (PTCA)===
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| [[PTCA]] has high initial [[revascularization]] success rates in the treatment of SVG [[stenosis]]. However, it is also associated with high rates of periprocedural complications, including acute vessel closure secondary to [[dissection]] and in-situ [[thrombosis]]. Additional complications include [[embolism|distal embolization]] and [[no reflow]], which can lead to periprocedural [[infarction]].
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| In modern [[interventional cardiology]], [[PTCA]] is not often used as the sole means of treatment for SVG [[stenosis]]. Instead, [[stenting]] has become the cornerstone of treatment, while the use of [[PTCA]] has been limited to pre-dilation and post-dilation.
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| ===PCI with bare metal stents (BMS) or drug-eluting stents (DES)===
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| Most current vein graft treatment strategies utilize PCI with stents ([[BMS]] or [[DES]]), since stenting is a superior treatment when compared to [[PTCA]] alone. As demonstrated in the SAVED (Saphenous Vein De Novo) Trial<ref name="pmid9287229">{{cite journal |author=Savage MP, Douglas JS, Fischman DL, ''et al.'' |title=Stent placement compared with balloon angioplasty for obstructed coronary bypass grafts. Saphenous Vein De Novo Trial Investigators |journal=N. Engl. J. Med. |volume=337 |issue=11 |pages=740–7 |year=1997 |month=September |pmid=9287229 |doi= |url=}}</ref>, the use of [[stents]] is associated with higher [[revascularization]] success rates, decreased [[restenosis]] rates, and improved clinical outcomes when compared to [[PTCA]]. Generally, [[DES]] are preferred over [[BMS]], since [[DES]] are associated with reduced rates of [[restenosis]] and target vessel [[revascularization]].
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| Despite their higher success rates, stents are not immune to [[restenosis]]. Predictors for [[restenosis]] include long [[stent]] length, multiple [[stents]], overlapping [[stents]], smaller vessel size, [[diabetes mellitus]], and [[stenosis]] at the coronary or aortic [[anastomosis]].
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| ===PCI with covered stents===
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| Theoretically, [[stents]] covered with a polymer membrane would have higher success rates than standard [[BMS]] and [[DES]]. One would expect covered stents to effectively trap friable [[atheroma]] and isolate the graft [[Lumen (anatomy)|lumen]] from the diseased wall, thereby reducing incidence of [[restenosis]], distal [[embolization]], and [[no reflow]] in comparison to traditional [[stents]]. However, the RECOVERS (The Randomized Evaluation of polytetrafluoroethylene COVERed stent in Saphenous vein grafts)<ref name="pmid12821546">{{cite journal |author=Stankovic G, Colombo A, Presbitero P, ''et al.'' |title=Randomized evaluation of polytetrafluoroethylene-covered stent in saphenous vein grafts: the Randomized Evaluation of polytetrafluoroethylene COVERed stent in Saphenous vein grafts (RECOVERS) Trial |journal=Circulation |volume=108 |issue=1 |pages=37–42 |year=2003 |month=July |pmid=12821546 |doi=10.1161/01.CIR.0000079106.71097.1C |url=}}</ref> and STING (STents IN Grafts)<ref name="pmid14563575">{{cite journal |author=Schächinger V, Hamm CW, Münzel T, ''et al.'' |title=A randomized trial of polytetrafluoroethylene-membrane-covered stents compared with conventional stents in aortocoronary saphenous vein grafts |journal=J. Am. Coll. Cardiol. |volume=42 |issue=8 |pages=1360–9 |year=2003 |month=October |pmid=14563575 |doi= |url=}}</ref> trials did not show any advantage in using covered [[stents]] when compared to [[bare metal stents]] for [[SVG lesions]].
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| ===Embolic protection devices===
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| During [[PCI]] of [[SVGs]], [[Atheroembolism|atheroembolic]] debris can be liberated. This debris contains [[vasoactive]] substances that can contribute to [[no reflow]], which can in turn considerably increase the risk of major adverse clinical events (MACE)<ref name="pmid16264199">{{cite journal |author=Salloum J, Tharpe C, Vaughan D, Zhao DX |title=Release and elimination of soluble vasoactive factors during percutaneous coronary intervention of saphenous vein grafts: analysis using the PercuSurge GuardWire distal protection device |journal=J Invasive Cardiol |volume=17 |issue=11 |pages=575–9 |year=2005 |month=November |pmid=16264199 |doi= |url=}}</ref>. Fortunately, embolic protection devices help capture this debris and improve outcomes in [[PCI]] for [[SVG]] [[stenosis]]. Therefore, it is recommended that these devices should be utilized in the intervention of most [[SVG]] lesions.
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| Currently, the [[FDA]] has approved five embolic protection devices in the United States. Specifically, these devices include one distal occlusion device, three filters, and one proximal occlusion device.
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| The FDA-approved distal occlusion device is called the PercuSurge Guardwire®, which involves inflating a balloon distal to the [[stenosis]] to occlude flow, thereby trapping the debris and [[vasoactive]] substances and preventing them from flowing downstream. Due to its small size, it requires little landing zone to deploy. The SAFER (Saphenous vein graft Angioplasty Free of Emboli Randomized) trial<ref name="pmid11901037">{{cite journal |author=Baim DS, Wahr D, George B, ''et al.'' |title=Randomized trial of a distal embolic protection device during percutaneous intervention of saphenous vein aorto-coronary bypass grafts |journal=Circulation |volume=105 |issue=11 |pages=1285–90 |year=2002 |month=March |pmid=11901037 |doi= |url=}}</ref> showed that when compared to conventional guidewires, balloon occlusion devices (PercuSurge Guardwire®) reduced the rates of infarction and [[no-reflow]] after intervention. Despite these advantages, the PercuSurge Guardwire® may not be the best option for all, as some patients may not tolerate the necessary 3-5 minutes of [[ischemic]] time associated with this device. Additionally, it is known to cause both [[hemodynamic]] and arrhythmic complications.
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| Filter devices allow continual distal perfusion while macroscopic [[emboli]] are trapped in the filter. The FIRE (FilterWire EX During Transluminal Intervention of Saphenous Vein Grafts) trial<ref name="pmid12874191">{{cite journal |author=Stone GW, Rogers C, Hermiller J, ''et al.'' |title=Randomized comparison of distal protection with a filter-based catheter and a balloon occlusion and aspiration system during percutaneous intervention of diseased saphenous vein aorto-coronary bypass grafts |journal=Circulation |volume=108 |issue=5 |pages=548–53 |year=2003 |month=August |pmid=12874191 |doi=10.1161/01.CIR.0000080894.51311.0A |url=}}</ref><ref name="pmid16569562">{{cite journal |author=Halkin A, Masud AZ, Rogers C, ''et al.'' |title=Six-month outcomes after percutaneous intervention for lesions in aortocoronary saphenous vein grafts using distal protection devices: results from the FIRE trial |journal=Am. Heart J. |volume=151 |issue=4 |pages=915.e1–7 |year=2006 |month=April |pmid=16569562 |doi=10.1016/j.ahj.2005.09.018 |url=}}</ref> showed that FilterWire may be preferred over PercuSurge Guardwire® due to improved clinical outcomes. While they may reduce [[ischemic]] time, filter devices are associated with their own set of potential complications. They are more difficult to deliver than balloon [[occlusion]] devices, so their own delivery may lead to distal [[embolization]], and they may not trap microscopic mediators of [[no reflow]]. Additionally, they require a significant landing zone distal to the [[lesion]] for the filter placement, which can be problematic for certain distal lesions that do not have enough room. There have also been case reports of filter entrapment in the [[Great saphenous vein#Use in cardiovascular procedures|graft]] after the completion of the [[PCI]].
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| The FDA-approved proximal occlusion device is called the Proxis® device. Some advantages of this decide are that its deployment does not require crossing the [[stenosis]], it provides superior support that is helpful where balloon or [[stent]] delivery is difficult, and it provides protected crossing of the [[lesion]], if required. However, as shown by the PROXIMAL (Proximal Protection During Saphenous Vein Graft Intervention Using the Proxis Embolic Protection System) trial<ref name="pmid17919563">{{cite journal |author=Mauri L, Cox D, Hermiller J, ''et al.'' |title=The PROXIMAL trial: proximal protection during saphenous vein graft intervention using the Proxis Embolic Protection System: a randomized, prospective, multicenter clinical trial |journal=J. Am. Coll. Cardiol. |volume=50 |issue=15 |pages=1442–9 |year=2007 |month=October |pmid=17919563 |doi=10.1016/j.jacc.2007.06.039 |url=}}</ref>, in terms of overall outcomes, there is no significant difference in death, [[MI]], or target vessel [[revascularization]] (TVR) between distal and proximal [[embolic]] protection devices.
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| ===Debulking/thrombus removal===
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| Data has not demonstrated a durable clinical benefit associated with [[debulking]]/[[thrombus]] removal. However, there are certain situations in which [[debulking]] techniques may be useful when treating [[saphenous vein grafts]]. For instance, severely [[calcified]] and [[stenotic]] [[lesions]] can make regular [[stent]] insertion especially difficult. When [[SVG]] [[lesions]] are too [[calcified]] to be crossed by a balloon or adequately dilated prior to [[stent]] placement, [[debulking]] and [[thrombus removal]] can change the compliance of the vessel wall. In addition, this technique is also useful if a [[lesion]] is at the aorto-ostial junction. Adjunctive stenting leads to better short and long term results.
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| There are several [[debulking]]/[[thrombus]] removal techniques, including directional coronary atherectomy, transluminal extraction catheter thrombectomy, rotational atherectomy, and laser atherectomy.
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| * Directional coronary atherectomy (DCA) uses a circular cutting blade that excises [[atheroma]] into a chamber for removal. It is useful for aorto-ostial [[lesions]] and focal [[lesions]] in large vessels. However, due to its bulky nature, it is generally not used in vessels with [[angulation]], [[tortuosity]], or heavy [[calcification]]. CAVEAT II (Coronary Angioplasty Versus Excisional Atherectomy Trial)<ref name="pmid7895354">{{cite journal |author=Holmes DR, Topol EJ, Califf RM, ''et al.'' |title=A multicenter, randomized trial of coronary angioplasty versus directional atherectomy for patients with saphenous vein bypass graft lesions. CAVEAT-II Investigators |journal=Circulation |volume=91 |issue=7 |pages=1966–74 |year=1995 |month=April |pmid=7895354 |doi= |url=}}</ref> examined how PTCA and DCA compared in the treatment of patients with coronary artery bypass graft stenoses. This study demonstrated that DCA was associated with higher initial angiographic success rates and larger acute luminal dimensions in comparison to PTCA. However, despite these successes, DCA also displayed an increased rate of non-Q wave myocardial infusion and distal embolization than PTCA. Furthermore, both techniques displayed similar [[restenosis]] rates.
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| :Additionally, a retrospective study compared DCA vs. [[PTCA]] alone vs. [[PCI]] with stenting in [[SVG]] lesions. It showed no differences in [[mortality]], [[angina]], [[infarction]], or repeat [[revascularization]] among the different methods. However, this study displayed increased angiographic complications with DCA use.
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| * Transluminal extraction catheter (TEC) thrombectomy is designed to remove [[thrombus]] from [[SVGs]] prior to stenting. It operates through the use of cutting blades with a rotating catheter and an external suction device. However, because the TEC Best trial showed no benefit of TEC prior to the stenting of [[SVGs]], this technique has fallen out of favor. Furthermore, TEC is also associated with a significant incidence of distal [[embolization]] and [[no reflow]].
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| * Rotational atherectomy (RA) uses a rotating cutting blade to grind [[calcified]] [[atheroma]]. Despite its ability to grind [[calcification]], this method is associated with high rates of [[no reflow]], distal [[embolization]], [[perforation]], and [[dissection]]. Furthermore, this method is [[contraindicated]] for [[lesions]] located in the body of [[SVGs]] or in degenerated vein grafts.
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| * Laser atherectomy uses [[monochromatic]] light energy to disrupt [[plaques]]. Despite this approach's innovation, there is no evidence that this strategy improves outcomes in lesions, and it has been complicated by high rates of [[dissection]] and [[perforation]].
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| ===Surgical revascularization===
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| Given increased perioperative [[mortality]], surgical revascularization is not an optimal treatment strategy, as many patients with [[graft disease]] are poor surgical candidates. However, surgery may be required in patients with multi-vessel disease and when [[PCI]] fails.
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| Additionally, reoperation is not strongly encouraged, as it does not provide the same level of [[revascularization]] and resolution of [[angina]] as the initial procedure. Furthermore, a [[LIMA]] may be jeopardized in a reoperation.
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| ==Making a selection==
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| At the earliest signs of recurrent [[ischemia]], it is important to strongly consider the possibility of a patent but [[stenosed]] [[SVG]], so that the graft [[lesion]] can be treated before the graft becomes completely [[occluded]]. Prompt treatment is essential, since a graft is lost once it becomes completely occluded.
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| Regardless of treatment choice, all patients should be given [[statins]] and [[aspirin]] (begun immediately following [[CABG]]), which are effective in the secondary prevention of [[SVG]] [[stenosis]].
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| For most [[SVG]] [[lesions]], [[PCI]] with [[stenting]] appears to be the therapy of choice. [[DES]] are associated with a decreased [[restenosis]] rate over [[BMS]], and should be used preferentially if the patient is able to tolerate dual platelet therapy for a minimum of a year. Furthermore, [[embolic]] protection devices should be strongly considered for all [[SVG]] [[lesions]], especially those with high risks for distal [[embolization]].
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| In cases in which [[stent]] delivery and expansion may be difficult due to heavily [[calcified]] and [[stenotic]] [[lesions]], [[atherectomy]] devices, used with stenting, may be considered. Furthermore, these devices can be useful in [[lesions]] that are aorto-ostial.
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| Zoghbi et al. conducted a study to investigate the role of pretreatment with [[nitroprusside]] before [[SVG]] intervention<ref name="pmid19182287">{{cite journal |author=Zoghbi GJ, Goyal M, Hage F, ''et al.'' |title=Pretreatment with nitroprusside for microcirculatory protection in saphenous vein graft interventions |journal=J Invasive Cardiol |volume=21 |issue=2 |pages=34–9 |year=2009 |month=February |pmid=19182287 |doi= |url=}}</ref>. They studied sixty-four consecutive patients with normal preprocedural cardiac [[enzymes]] that underwent [[SVG]] [[PCI]], without the use of [[embolic]] protection devices. They found that pretreatment with [[nitroprusside]] results in a lower magnitude and frequency of post-procedural cardiac [[enzyme]] elevation. Thus, it is important to consider [[nitroprusside]] use.
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| Finally, while [[Glycoprotein IIb/IIIa inhibitors|GP IIb/IIIa inhibitors]] are frequently used in the setting of [[SVG]] intervention, their benefit has not been fully evaluated in randomized trials of this lesion subset.
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| ==Other concerns==
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| As with all medical procedures, complications for [[SVG]] intervention can occur. Risk factors for complications include: older [[graft]] age (>3-5 years), the presence of [[thrombus]], and diffuse disease.
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| Although [[PCI]] with [[stenting]] is effective for focal lesions, there is uncertainty regarding the best treatment for diffusely degenerated [[SVGs]]. In these cases, it is often a better choice to abandon the [[graft]] and intervene on the native vessel instead.
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| As mentioned above, prevention of [[no reflow]] should be attempted with [[embolic]] protection devices, pretreatment using [[nitroprusside]] and the avoidance of high-pressure inflations and unnecessary pre/post-dilation and oversizing. However, in the event that [[no reflow]] develops, it should be aggressively managed with intracoronary [[vasodilators]] (i.e. [[diltiazem]], [[nicardipine]], [[adenosine]], and [[nitroprusside]]).
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| ===Pathological findings===
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| [http://www.peir.net Images courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology]
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| <gallery perRow="3">
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| Image:Saphenous vein graft 001.jpg|Saphenous vein coronary bypass graft: Gross, natural color, external view of heart with thrombosed veins
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| Image:Saphenous vein graft 002.jpg|Saphenous vein coronary bypass graft: Thrombosis, Acute: Gross, fixed tissue but well shown cross sections of bypass graft and anastomotic site with thrombosis. 61 yo male, with and acute infarct treated with streptokinase and two days later had bypass. Died 5 days post op. Two veins are thrombosed
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| Image:Saphenous vein graft 003.jpg|Myocardial Infarct Acute Reflow Type: Gross, fixed tissue but good color. A very enlarged heart with moderate LV dilation and high anterior wall hemorrhagic infarct. Initially treated with streptokinase and two days later had saphenous vein grafts. Both grafts are thrombosed. He died after 5 days
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| </gallery>
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| | ==[[Coronary artery bypass surgery perioperative medical therapy|Perioperative Medical Therapy]]== |
| | [[Coronary artery bypass surgery aspirin and clopidogrel|Aspirin and Clopidogrel]] | [[Coronary artery bypass surgery use of beta-blockers|Beta-Blockers]] | [[Coronary artery bypass surgery use of ACE Inhibitors/ARBs|ACE Inhibitors/ARBs]] | [[Coronary artery bypass surgery management of hyperlipidemia|Management of Hyperlipidemia]] | [[Coronary artery bypass surgery management of perioperative infection|Management of Mediastinitis/Perioperative Infection]] | [[Coronary artery bypass surgery percutaneous coronary intervention (PCI) to treat saphenous vein graft failure|Percutaneous Coronary Intervention (PCI) To Treat Saphenous Vein Graft Failure]] | [[Coronary artery bypass surgery perioperative management of myocardial ischemia|Perioperative Management of Myocardial Ischemia]] | [[Coronary artery bypass surgery postoperative antiplatelet therapy|Postoperative Antiplatelet Therapy]] | [[Coronary artery bypass surgery maintaining glucose level|Maintaining Glucose Level]] |
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| ==References== | | ==References== |