CABG, coronary artery bypass grafting; EF, ejection fraction; LAD, left anterior descending; LIMA, left internal mammary artery; LMT, left main trunk.

^* Odds ratio > 1 denotes a higher likelihood of PCI.

^† Odds ratio calculated for 75th vs. 25th percentile for the respective variable in the cohort.

From Brener SJ, Lytle BW, Casserly IP, et al. Predictors of revascularization method and long-term outcome of percutaneous coronary intervention or repeat coronary bypass surgery in patients with multivessel coronary disease and previous coronary bypass surgery. Eur Heart J. 2006;27:413–418.

Early Postoperative Period

The performance of routine intraoperative angiography at the conclusion of CABG at one center and three recent trials in which routine angiography was performed at 6 to 12 months to assess graft patency have provided sobering insights regarding contemporary CABG.⁹^–¹² Among 366 consecutive patients who underwent intraoperative completion angiography, Zhao and colleague found that 12% of bypass grafts had defects important enough to require intervention (open surgical revision 3.4%, open-chest PCI 6%, and minor adjustment 2.8%).⁹ In a randomized trial of over 3,000 patients, graft failure at 1 year occurred in 30% of saphenous vein grafts (SVGs),¹⁰ while SVG failure occurred in 23% performed off pump and 16% on pump in another report,¹¹ and 38% of gastroepiploic artery grafts failed in a third.¹² Graft failure was associated with death, new MI, or repeat revascularization in 26% of patients.¹⁰ Recurrent ischemia within days of surgery is usually related to acute vein graft thrombosis. However, stenosis may exist at proximal or distal anastomoses (Fig. 25-1); a bypass graft may be kinked; the wrong vessel may have been bypassed; or the revascularization may have been rendered incomplete as a result of diffuse disease, stenoses distal to graft insertion, or inaccessible intramyocardial position of a recipient artery. To determine the cause of severe early postoperative myocardial ischemia and define therapeutic options, coronary arteriography has been carried out within a few hours of surgery in 3% to 4% of patients in some centers,¹³^–¹⁵ and this strategy is recommended. PCI in patients with early ischemia after CABG is a class I indication in the American College of Cardiology/American Heart Association/Society for Cardiovascular Angiography and Interventions (ACC/AHA/SCAI) PCI guidelines.¹⁶ Although 44 (29%) of 145 patients catheterized because of ischemia early after surgery had no apparent cause for ischemia, most patients had correctable problems; 30 patients had emergency reoperation, and 44 underwent PCI.¹³^–¹⁵ Graft occlusion or stenosis was present in about 60% of catheterized patients. In 7 patients, focal stenosis was present in a venous or arterial graft distal anastomosis, and balloon dilation across suture lines was safe in these patients. However, in our experience (Fig. 25-2) and in that of others, extreme care is warranted even a few hours after surgery to ensure an intracoronary position of the steerable guidewire. In addition, balloon sizing should be conservative, because we are aware of unreported cases of suture-line disruption and severe hemorrhagic complications. Immediate access to a covered stent is essential should suture line perforation occur. Patients at increased risk for early postoperative ischemia include those undergoing minimally invasive and “off-bypass” techniques and those receiving non-internal mammary artery (IMA) arterial grafts. When ischemia recurs 1 to 12 months after surgery, perianastomotic stenoses are among the most common problems (Fig. 25-3). Stenotic lesions of the distal anastomosis of saphenous vein or arterial grafts can be successfully dilated with balloon angioplasty at this time with little morbidity and good long-term patency in 80% to 90% of patients.^3,¹⁷ Stenoses, or in some cases total occlusions, of the middle or distal portions of the IMA or radial artery grafts may be dilated successfully (Fig. 25-4), especially when the presence of a short occlusion can be documented. Stenotic lesions of mid-SVGs occurring within a year of surgery are usually due to intimal hyperplasia; these lesions can be dilated with balloon angioplasty and/or stented with little risk of distal embolization, but recurrence in about 50% of cases in our experience and periprocedural graft perforation has been observed. Stents, directional atherectomy, and excimer laser angioplasty have all been tried for the treatment of proximal anastomotic lesions with excellent initial results but significant rates of restenosis. There are few data regarding use of drug-eluting stents at this site.

Figure 25-1 Sites of saphenous vein graft stenoses. All lesions between the proximal and distal anastomoses are considered midgraft lesions.

Figure 25-2 Two cases of failure of minimally invasive CABG treated with percutaneous catheter-based intervention. Patient 1: A 78-year-old woman underwent left internal mammary artery (LIMA) to left anterior descending coronary artery (LAD) through a left fourth intercostal incision without cardiopulmonary bypass because of refractory angina and a long stenosis of a tortuous LAD. Angina at rest recurred within a few hours after surgery, and angiography on the second postoperative day revealed occlusion of the LIMA graft about 4 cm from its insertion into the LAD (A, arrow). The LAD was tortuous, with multiple, severe stenoses (B, arrows), and left ventricular function was normal. Angioplasty and stent implantation in the native vessel yielded an excellent angiographic result (C, arrows) and favorable short-term follow-up. Patient 2: Because of disabling angina and a long proximal LAD stenosis, a 60-year-old man underwent minimally invasive LIMA to LAD. About 2 hours after surgery, an ECG showed anterior ST-segment elevation, and emergency coronary arteriography revealed occlusion of the distal LAD at the graft insertion (D, left lateral view, arrow). Balloon angioplasty through the LIMA graft was successful (E, arrow), and the patient remained asymptomatic at 6-month follow-up.

Figure 25-3 A 37-year-old woman had placement of saphenous vein grafts to the left anterior descending (LAD) and posterior descending coronary arteries. Unstable angina recurred 3 months later, and high-grade stenosis was present at the junction of the saphenous vein graft to the LAD (A, top, arrow). The circumflex coronary artery had minimal disease (A, bottom). The saphenous vein graft to the posterior descending coronary artery was patent. Balloon angioplasty of the distal anastomosis was successful. Disabling angina recurred 9 months following CABG. Coronary arteriography (B, top) showed a widely patent distal anastomosis but high-grade stenosis of the circumflex coronary artery (B, bottom, arrow) unresponsive to nitroglycerin. Balloon angioplasty of the circumflex stenosis was successful (residual stenosis 5%). Twelve years following CABG, angina recurred and recatheterization showed high-grade stenosis of the mid-LAD just beyond the takeoff of a large diagonal (C, top left, arrow); the vein graft to the posterior descending coronary artery was occluded. Previous PTCA sites at the distal anastomosis of the vein graft to the LAD and the circumflex artery (C, bottom) were widely patent. Balloon angioplasty of the mid-LAD was successful. The patient remained asymptomatic for 4.5 years, when a new thrombotic stenosis in the midportion of the SVG to the LAD led to replacement of this graft with a LIMA. All prior PTCA sites were patent. Surgical benefit was extended over 16 years with three percutaneous procedures.

Figure 25-4 A 52-year-old man experienced recurrence of angina 5 months after triple coronary bypass. Coronary arteriography revealed total occlusion of the LIMA 1 to 2 cm proximal to insertion into the LAD coronary artery (A, arrow), severe stenosis of a large diagonal, and patent grafts to the obtuse marginal and right coronary arteries. The LIMA was recanalized by use of an 8-Fr IMA guide catheter for good backup, progression to a relatively stiff guide wire to punch across the total occlusion, and a 2-mm over-the-wire balloon (post-PTCA result: B, arrow). The diagonal was successfully dilated. The patient presented again 5 years later with recurrent angina and was found to have an occluded SVG to the obtuse marginal artery; the native obtuse marginal artery was successfully dilated. The LIMA-to-LAD anastomosis was widely patent (C), as was the diagonal, 5 years after recanalization.

1 to 3 Years after Surgery

Patients with recurrent ischemia 1 to 3 years after surgery frequently have new stenoses in graft conduits and native coronary arteries that are amenable to percutaneous intervention. Whenever possible, native coronary lesions are targeted. ACC/AHA/SCAI PCI guidelines consider focal ischemia-producing graft lesions in patients 1 to 3 years after CABG with preserved left ventricular function to be a class IIa indication (“conflicting evidence, weight of evidence/opinion in favor of usefulness”).

More than 3 Years after Surgery

Beginning about 3 years after implantation, atherosclerotic lesions appear in vein grafts with increasing frequency. Unstable ischemic syndromes are common, and aggressive invasive evaluation and therapy are indicated. In about 70% of post-CABG patients presenting with acute coronary syndrome, the culprit lesion is located in a SVG. Atherosclerotic plaques in vein grafts contain foam cells, cholesterol crystals, blood elements, and necrotic debris, with less fibrocollagenous tissue and calcification than is present in native coronary arteries (Fig. 25-5). Consequently the plaques in older vein grafts may be softer and more friable as well as being larger than those observed in native coronary arteries, and they frequently have associated thrombus formation (Fig. 25-6). Atheroembolism related to graft intervention may have catastrophic consequences. Consequently bulky vein graft lesions (those with a large potential atheroma mass) should be avoided if possible and embolic protection utilized if not. Improved initial outcome has been reported with stent placement compared with balloon dilation in SVGs. However, long-term results in SVGs, even with stents, have been disappointing. Data on long-term outcomes with drug-eluting stents in SVGs are limited (see below). The role of percutaneous techniques in totally occluded SVGs is controversial. Balloon angioplasty alone has resulted in high complication rates and low patency in most reports. Unfortunately, prolonged intracoronary thrombolytic therapy has been associated with thromboembolic MI, hemorrhagic complications, and relatively low long-term patency. ACC/AHA/SCAI guidelines consider chronically occluded SVG intervention to be a class III indication (“procedure not useful, may be harmful”).

Figure 25-5 A and B. Vein graft. A. Low-power photomicrograph shows rupture (arrowheads) of atheromatous plaque caused by balloon angioplasty and secondary thrombosis (Thr). Sections taken at adjacent sites were involved by such extensive disruption that luminal boundaries were obliterated. B. High-power photomicrograph demonstrates nature of plaque, with foam cells, cholesterol clefts, blood elements, and necrotic debris. C and D. Intramural coronary artery branches. Atheromatous emboli obstruct vessels in anterolateral (C) and inferoseptal (D) walls of left ventricle (compare with B).

(From Saber RS, Edwards WD, Holmes DR Jr, et al. Balloon angioplasty of aortocoronary saphenous vein bypass grafts: A histopathologic study of six grafts from five patients, with emphasis on restenosis and embolic complications. J Am Coll Cardiol 1988;12:1501–1509.)