Antithrombotic Therapy in Patients With Saphenous Vein and Internal Mammary Artery Bypass Grafts Following Percutaneous Transluminal Coronary Angioplasty

doi:10.1378/chest.102.4_Supplement.508S

Chest

Volume 102, Issue 4, Supplement, October 1992, Pages 508S-515S

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1.
It is standard practice, in patients undergoing coronary angioplasty, to administer heparin during the procedure. The usual dose is 10,000 U administered intravenously, followed by a continuous infusion or intermittent heparin to maintain therapeutic levels. We found no evidence to indicate that this standard should be modified.
2.
There is no evidence that prolonged (18 to 24 h) heparin is of any benefit over a few hours in preventing acute thrombosis in patients who had uncomplicated procedures (level II).³³ Based upon standard practice, heparin for 16 to 24 h is administered for unstable angina, complex lesions, multivessel angioplasty, and a suboptimal result.
3.
Antiplatelet agents (in addition to heparin) reduce periprocedural coronary thrombosis and are indicated (level I and II studies).²⁶^,²⁷
4.
Aspirin alone was as effective as aspirin plus dipyridamole (level II).³⁰
5.
The dose of aspirin that was used in most studies was 650 mg/day to 990 mg/day²⁶^,²⁷^,³⁰ (although sometimes with dipyridamole), and aspirin was started before the angioplasty. Lower doses of aspirin (80 mg/day), started one day before the angioplasty, were also effective (level II).²⁹
6.
The evidence that antiplatelet agents may prevent or modify late restenosis is inconsistent²⁶ (level II),²⁸ (level IV),³⁶ (level I).
7.
Warfarin, in small size studies, was not effective in preventing late restenosis (level II),³⁸ but it was not worse than aspirin (level II).³⁹

Section snippets

SAPHENOUS VEIN BYPASS GRAFTS

Over one half of the randomized prospective studies of anticoagulants or antiplatelet agents on saphenous vein graft closure have shown a beneficial effect of therapy1, 2, 3, 4, 5, 6, 7, 8, 9 (Table 1). This applies to studies of aspirin alone in various doses,¹^,³ aspirin plus dipyridamole,3, 4, 5, 6 sulfinpyrazone,⁷ ticlopidine,⁹ and warfarin.⁸ Studies in which aspirin was administered before operation³ or within one day after operation¹ showed a beneficial effect, irrespective of the dose of

INTERNAL MAMMARY ARTERY BYPASS GRAFTS

Regarding the use of antìplatelet agents in patients with internal mammary artery bypass grafts, information is limited. Among 45 patients with left internal mammary artery to left anterior descending coronary artery bypass grafts, 18 received aspirin, 1,300 mg/day, as well as dipyridamole, 100 mg/day, beginning one day after operation.⁶ Following three to six months of observation, graft patency was similar in the control and treatment groups: 26 of 27 (96 percent) vs 18 of 18 (100 percent)

BLEEDING COMPLICATIONS: CORONARY ARTERY BYPASS GRAFTS

Information regarding bleeding complications of various regimens of antithrombotic therapy following saphenous vein bypass graft surgery is sparse. In a retrospective study, the estimated odds ratio for reoperation for bleeding following coronary artery bypass grafting was 1.82 among patients who received aspirin (dose unstated) within seven days prior to surgery (level IV).²³ Among patients in whom chest tube drainage was measured, those who received aspirin prior to surgery had more chest

SUMMARY: CORONARY ARTERY BYPASS GRAFTS

1.
Aspirin alone may be as effective as aspirin in combination with dipyridamole when both are started before operation,³ but aspirin plus dipyridamole is more effective than aspirin alone, when dipyridamole is started before surgery and aspirin is started after operation.²¹
2.
Aspirin, 325 mg/day, is as effective as aspirin, 975 mg/day, or aspirin, 975 mg/day, plus dipyridamole, 225 mg/day,³ and both are more effective than sulfinpyrazone.³ Bleeding may be less with the lower dose of aspirin.³
3.
Aspirin

PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY (PTCA)

Antiplatelet agents, when started before the procedure, have been shown to be beneficial in the prevention of periprocedural events associated with PTCA (level I, II studies)²⁶^,²⁷ (Table 4). Fewer patients had myocardial infarctions and fewer required emergency coronary artery bypass grafts when aspirin plus dipyridamole or ticlopidine was administered prior to PTCA²⁶^,²⁷ (Table 4).

Patients who, starting before the procedure, were administered aspirin alone or in combination with dipyridamole,

LONG-TERM EFFECTS AND LATE RESTENOSIS

Regarding restenosis, antiplatelet agents have shown inconsistent benefits (Table 5). Schwartz and associates²⁶ showed a similar number of patients with restenosis four to seven months after PTCA among patients treated with aspirin, 990 mg/day, plus dipyridamole, 225 mg/day, vs placebo, 46 of 122 (38 percent) vs 49 of 127 (39 percent) (NS) (level II). The severity of restenosis, however, was less in the 40 segments in the active treatment group than in the 46 segments in the placebo group (mean

RECOMMENDATIONS: CORONARY ARTERY BYPASS GRAFTS

1.
It is recommended that antiplatelet agents be administered to reduce the frequency of saphenous vein bypass graft closure. This recommendation is based upon several level I and level II studies that showed significant benefits of therapy,¹^,3, 4, 5, 6, 7^,⁹^,¹⁷ as well as meta-analysis that included additional studies, the individual results of which did not reach significance.¹⁶
2.
Aspirin alone is recommended. The dose of aspirin that has been shown to be beneficial in graft patency in rigorously

RECOMMENDATIONS: PTCA

1.
Heparin, 10,000 U intravenously, followed by a continuous infusion of heparin, or intermittent heparin to maintain the activated partial thromboplastin time 1.5 to 2 times control is recommended on the basis of standard practice.
2.
It is recommended that heparin be discontinued 2 to 4 h after the conclusion of an uncomplicated procedure (level II).³³ Based upon standard practice, heparin for 16 to 24 h is recommended for unstable angina, complex lesions, multivessel angioplasty, and a suboptimal

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Cited by (14)

Gene delivery to aortocoronary saphenous vein grafts in a large animal model of intimal hyperplasia
2004, Journal of Thoracic and Cardiovascular Surgery
More than 50% of aortocoronary saphenous vein grafts are occluded 10 years after surgery. Intimal hyperplasia is an initial, critical step in the progression toward occlusion. To date, no clinically relevant large animal models of aortocoronary saphenous vein graft intimal hyperplasia have been fully characterized. Gene therapy holds promise as a novel treatment for aortocoronary saphenous vein graft intimal hyperplasia. The 2 objectives of this study are to characterize a canine model of aortocoronary saphenous vein graft intimal hyperplasia and to demonstrate that ex vivo gene delivery is possible in these grafts using adenoviral vectors.
Ten dogs underwent aortocoronary bypass grafting using saphenous veins. Six dogs underwent serial arteriograms to monitor graft patency. On postoperative day 90, the dogs were killed and their grafted and nongrafted saphenous veins were studied histologically. Four dogs underwent the same procedure, but their saphenous veins were treated with 1 × 10¹² total viral particles of a replication-deficient, recombinant adenovirus containing β-galactosidase (n = 2) or the β-adrenergic receptor kinase carboxyl terminus (n = 2). These animals were killed on postoperative day 7 for determination of transgene expression.
All grafts were demonstrated patent by arteriogram before the animals were killed. The mean intimal area of the saphenous vein grafts was increased when compared with that of the nongrafted saphenous veins (2.83 mm² vs 0.09 mm², P < .0008). Adenoviral-treated saphenous vein grafts demonstrated positive transgene expression either by X-gal staining (β-galactosidase) or Northern analysis (β-adrenergic receptor kinase carboxyl terminus).
This study characterizes a clinically relevant canine model of aortocoronary saphenous vein graft intimal hyperplasia. In addition, it demonstrates that adenoviral vectors can be delivered ex vivo to the saphenous vein graft vessel wall at subphysiologic distension pressures. This model may be used in future studies to manipulate molecular targets critical in aortocoronary saphenous vein graft intimal hyperplasia.
Antithrombotic prophylaxis in arterial and venous vessel diseases
1995, Fibrinolysis and Proteolysis
This is a comprehensive description of the state of the art in preventing occurrence and progress of thrombotic and thromboembolic diseases. Anticoagulation with different heparin preparations and with oral anticoagulants as well as antiplatelet drugs, alone or in combination have their particular indications in patients with arterial and venous vessel diseases. Based upon recent clinical trials, recommendations are given for the clinical practice.
Antithrombotic therapy in patients with saphenous vein and internal mammary artery bypass grafts
1995, Chest
High stress regions in saphenous vein bypass graft atherosclerotic lesions
1994, Journal of the American College of Cardiology
Objectives. Our aim was to test the hypothesis that maximal stresses in saphenous vein atherosclerotic stenoses are greater than those in native coronary artery stenoses.
Background. The patency of coronary artery saphenous vein bypass grafts decreases with time, usually because of thrombosis. Plaque rupture has been described as one mechanism of vein graft thrombosis.
Methods. Twenty-six nonruptured human lesions were studied. Fourteen lesions were from native coronary arteries, and 12 were from saphenous vein bypass grafts placed a mean ± SD of 9.8 ± 3.3 years before pathologic study. The finite element method was used to determine the distribution of stress in the lesion, using estimates of material properties from previous measurements of human tissues.
Results. Maximal circumferential stresses were significantly higher in the saphenous vein lesions (median 352 kPa [interquartile range 161 to 475]) than in the coronary artery lesions (median 104 kPa [interquartile range 75 to 185]) (p = 0.05). Thin-walled cylinder formulations predict that stresses are proportional to the radius of the vessel and inversely proportional to the minimal wall thickness. In this study, there was a good correlation between the maximal stress in the 26 lesions and the ratio of the square root of lumen area to minimal fibrous cap thickness (r = 0.83, p < 0.001).
Conclusions. Maximal circumferential tensile stresses in saphenous vein bypass graft stenoses are higher than in native coronary artery atherosclerotic stenoses. These data suggest that strategies that decrease stresses in bypass graft atherosclerotic lesions, such as prevention of lipid accumulation, could reduce the probability of plaque rupture in bypass grafts.
Antithrombotic therapy in patients with heart valve prostheses
2013, Cardiology in Review
Biomechanical considerations in the design of graft: The homeostasis hypothesis
2006, Annual Review of Biomedical Engineering

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Chest

Antithrombotic Therapy in Patients With Saphenous Vein and Internal Mammary Artery Bypass Grafts Following Percutaneous Transluminal Coronary Angioplasty

Section snippets

SAPHENOUS VEIN BYPASS GRAFTS

INTERNAL MAMMARY ARTERY BYPASS GRAFTS

BLEEDING COMPLICATIONS: CORONARY ARTERY BYPASS GRAFTS

SUMMARY: CORONARY ARTERY BYPASS GRAFTS

PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY (PTCA)

LONG-TERM EFFECTS AND LATE RESTENOSIS

RECOMMENDATIONS: CORONARY ARTERY BYPASS GRAFTS

RECOMMENDATIONS: PTCA

Lancet

Ann Thorac Surg

Am J Cardiol

J Thorac Cardiovasc Surg

Am J Cardiol

Am J Cardiol

Lancet

Ann Thorac Surg

Am J Cardiol

Am Heart J

Am Heart J

Am J Cardiol

Am Heart J

J Am Coll Cardiol

Am J Cardiol

Lancet

Improved graft patency in patients treated with platelet-inhibiting therapy after coronary bypass surgery

Circulation

Improvement in early saphenous vein graft patency after coronary artery bypass surgery with antiplatelet therapy: results of a Veterans Administration cooperative study

Circulation

Acetylsalicylic acid and dipyridamole improve the early patency of aorta-coronary bypass grafts

J Thorac Cardiovasc Surg

Improved graft patency with anticoagulant therapy after aortocoronary bypass surgery: a prospective, randomized study

Circulation