Cardiology

Saphenous Vein Graft Intervention

General description of procedure, equipment, technique

Saphenous vein graft (SVG) percutaneous coronary interventions (PCI) have important differences compared to native coronary artery interventions:

1.    Finding the grafts may be difficult and also engaging, and delivering equipment can be challenging due to poor guide catheter support.

2.    SVGs have higher risk for distal embolization and periprocedural myocardial infarction.

3.    Embolic protection devices (EPDs) have been shown to be beneficial in SVGs but not in native coronary arteries.

4.    SVGs have higher restenosis rates.

5.    Patients undergoing SVG interventions are usually older and have more comorbidities, and as a result, they are at higher risk for subsequent adverse events, both related and unrelated to the cardiovascular system.

Indications and patient selection

Most patients with prior coronary artery bypass graft surgery who present with SVG lesions causing ischemia are treated with PCI, because repeat coronary artery bypass surgery carries increased risk for complications, especially in patients with patent left internal mammary artery grafts to the left anterior descending artery.

However, repeat coronary bypass surgery should be considered in patients with multiple diseased or occluded grafts, availability of the left internal mammary artery for grafting the left anterior descending artery, good CABG targets, and lack of significant comorbidities.

Contraindications

PCI of chronic total SVG occlusions carries low procedural success and high restenosis rates, and is currently not recommended (class III recommendation in the 2011 ACC/AHA PCI guidelines).

Details of how the procedure is performed

Finding and engaging the grafts

Knowledge of the bypass graft anatomy is very important to facilitate bypass graft localization and engagement. Every effort should be made to obtain the coronary bypass surgical report before starting the catheterization procedure.

If the coronary artery bypass graft anatomy is not known, then native angiography can provide clues about the presence of patent grafts, either by visualization of competitive flow, or by no visualization of blood flow into a vascular territory, which in most cases would imply that the territory is supplied by a patent graft.

Bypass graft markers greatly facilitate engagement but are not placed in most patients. We routinely perform bilateral subclavian artery angiography to determine whether one or both internal mammary arteries are used as grafts, and whether proximal subclavian artery stenosis is present, which could lead to subclavian steal syndrome.

If questions remain about bypass graft anatomy, ascending aortography is performed, using a pigtail catheter placed 1 cm above the aortic valve (usual injection rate is 20 mL/sec for a total volume of 60 mL). Graft engagement is easier using femoral access.

If radial access is used, using the left radial can facilitate engagement of the left internal mammary artery graft. A JR4 or 3DRC catheter can usually engage most grafts; however, a multipurpose catheter works best for SVGs supplying the right coronary/posterior descending artery, and a left coronary bypass or Amplatz catheter works best for left-sided grafts.

We favor engagement using large "up and down" catheter movements with the left hand, with small rotation using the right hand. Usually SVGs supplying the left anterior descending artery are placed lower in the aorta; SVGs supplying diagonals are implanted higher, and SVGs supplying obtuse marginal branches are implanted even higher in the aorta.

Use of guide catheter extensions, such as the GuideLiner catheter (Vascular Solutions, Minneapolis) can facilitate graft engagement and provide additional support for equipment delivery.

Adjunctive pharmacotherapy

Glycoprotein IIb/III inhibitor administration has not been shown to provide benefit in SVGs and should not be used, except possibly in cases with SVG occlusion with large thrombus burden (class III recommendation in the 2011 ACC/AHA PCI guidelines). Either heparin or bivalirudin can be used for anticoagulation, with bivalirudin having a lower risk for bleeding complications.

We frequently administer intragraft vasodilators prophylactically before SVG PCI, but also after PCI if slow flow occurs. Adenosine, nitroprusside, nicardipine, and verapamil can be used (we prefer nicardipine, which produces more prolonged vasodilation compared with the other medications).

Embolic protection

EPDs significantly reduce the risk for distal embolization, slow-flow, and periprocedural myocardial infarction (by approximately 40%). Embolic protection should be used in all SVG interventions with the following exceptions: (1) in-stent restenotic lesions, which are composed of fibrous tissue and have low embolization risk, (2) recently implanted (<2 year-old SVG, that have not had enough time to develop significant degeneration predisposing to embolization, and (3) when EPD use is not technically feasible (which at present applies mostly to distal or anastomotic lesions, since proximal embolic protection devices are no longer available for clinical use in the United States).

Three EPDs are currently available in the U.S. for use in SVG interventions: the Guardwire (Medtronic Vascular, Santa Rosa, CA), which is a 0.014-inch guidewire with a distal wire-mounted balloon, and two filters; the Filterwire (Boston Scientific, Natick, MA); and the Spider (ev3, Plymouth, MN). The Guardwire works by occluding the distal SVG lumen, hence blocking distal embolization of debris or vasoactive substances liberated during SVG intervention, which are aspirated before the Guardwire balloon is deflated, restoring antegrade flow.

EPD selection depends on operator training and preference. In general filters are easier to use than the Guardwire and hence preferred by most operators. The SVG lesion location is also important: ostial lesions should only be protected with a filter because use of a distal occlusion balloon may result in embolic debris embolizing in the aorta; body lesions can be protected using any device; distal anastomotic lesions cannot be protected with the currently available devices. Although most patients tolerate ischemia well, some may not tolerate use of the Guardwire, especially when used in large SVGs supplying a large myocardial territory.

Stent implantation

We recommend routine intravascular imaging of SVGs, usually using intravascular ultrasound, to determine the optimal stent length and diameter. This is especially important in large SVGs, in which diameter can be overestimated or underestimated.

A report from the Washington Hospital Center suggested that slightly undersizing the stents resulted in lower rates of periprocedural myocardial infarction without causing higher restenosis rates when drug-eluting stents were used. Slightly undersizing the stents would also decrease the risk of a rare, but dramatic, complication: SVG perforation.

We recommend use of drug-eluting stents in most patients, as they decrease the risk for in-stent restenosis (as shown in the largest randomized-controlled trial performed to date, the Is Drug-Eluting-Stenting Associated with Improved Results in Coronary Artery Bypass Grafts? (ISAR-CABG) study, unless there is a contraindication (bleeding diathesis, poor compliance with medications, planned surgery within the ensuing 12 months).

Interpretation of results

N/A

Performance characteristics of the procedure (applies only to diagnostic procedures)

N/A

Outcomes (applies only to therapeutic procedures)

In subtotally occluded SVGs, high success rates (>90%) can be achieved with approximately 10% risk of periprocedural complications (mainly periprocedural myocardial infarction). In acutely occluded thrombotic SVGs, success rates for intervention are lower, approximately 80%. Patients undergoing SVG interventions have high risk for subsequent cardiovascular and noncardiovascular events, with approximately 5% mortality during the first year after the procedure.

Alternative and/or additional procedures to consider

Before performing a SVG intervention, it is important to consider whether intervention of the native coronary artery supplying the same territory could be performed. Intervention in native coronary arteries carries lower procedural risk and better long-term outcomes. In some cases, treatment of native coronary artery chronic total occlusion has been performed after attempts to recanalize a SVG fail, but these procedures are very complex and should only be performed at experienced centers.

Complications and their management

SVG interventions have similar complications to non-SVG interventions; however, the risk of distal embolization and no-reflow is significantly higher in SVGs due to diffuse SVG degeneration and frequent presence of thrombus. EPDs can decrease the distal embolization risk, but do not eliminate it.

If slow-flow or no reflow occurs post-SVG stent implantation using filter-based embolic protection, then we recommend performing aspiration thrombectomy to retrieve any liberated debris that may be obstructing the filter. Occasionally the filter may need to be removed to restore antegrade flow.

If more angioplasty or stenting is required, it is best to insert a second filter prior to proceeding with PCI. Intragraft vasodilator administration can also help restore antegrade flow.

Additional stent implantation should not be performed until after normal antegrade flow is restored. SVG perforation is rare and is usually caused by deployment of oversized stents.

If SVG perforation occurs, the stent balloon is immediately inflated to stop blood flow into the pericardium. Heparin is reversed and pericardiocentesis is performed if the patient develops tamponade.

If pericardial leaking continues, a second arterial access is obtained and a covered stent is delivered using a second 7 or 8 Fr guide catheter in an effort to minimize the time that the perforation site is uncovered. Equipment entrapment is another potential complication of SVG intervention.

To minimize this risk, use of buddy wires is discouraged when a filter is used for embolic protection. Lost stents or wire fragments can be retrieved using standard techniques, such as the small balloon technique or loop snares.

What’s the evidence?

Baim, DS, Wahr, D, George, B. "Randomized trial of a distal embolic protection device during percutaneous intervention of saphenous vein aorto-coronary bypass grafts". Circulation. vol. 105. 2002. pp. 1285-90.

(Saphenous vein graft Angioplasty Free of Emboli Randomized [SAFER] trial: this is the first and only randomized controlled trial that compared the use of an embolic protection device vs. no embolic protection in 801 patients undergoing SVG intervention. Use of the Guardwire (Medtronic Vascular, Santa Rosa, CA) reduced the 30-day risk of death, myocardial infarction, emergency bypass, or target lesion revascularization by 42%, establishing EPDs as a useful strategy for preventing periprocedural myocardial infarction in SVGs.)

Stone, GW, Rogers, C, Hermiller, J. "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". Circulation. vol. 108. 2003. pp. 548-53.

(FilterWire EX Randomized Evaluation [FIRE] trial: noninferiority trial showing that the Filterwire [Boston Scientific, Natick, MA] was noninferior to the Guardwire [Medtronic Vascular] in preventing major adverse events after SVG interventions.)

Mauri, L, Cox, D, Hermiller, J. "The PROXIMAL trial: proximal protection during saphenous vein graft intervention using the Proxis Embolic Protection System: a randomized, prospective, multicenter clinical trial". J Am Coll Cardiol. vol. 50. 2007. pp. 1442-9.

(Proximal Protection During Saphenous Vein Graft Intervention [PROXIMAL] trial: study showing noninferiority of proximal embolic protection using the Proxis device [St. Jude Medical, Minneapolis] compared to distal embolic protection using the Guardwire and the Filterwire. Since 2012, the Proxis device is no longer commercially available in the U.S.)

Vermeersch, P, Agostoni, P, Verheye, S. "Increased late mortality after sirolimus-eluting stents versus bare-metal stents in diseased saphenous vein grafts: results from the randomized DELAYED RRISC Trial". J Am Coll Cardiol. vol. 50. 2007. pp. 261-7.

(Reduction of Restenosis In Saphenous vein grafts with Cypher sirolimus-eluting stent trial [RRISC] trial: this was the first randomized controlled trial of drug-eluting stents [sirolimus-eluting] in SVGs [75 patients] and raised concerns about the long-term safety of drug-eluting stents [DES] by showing significantly higher mortality during a median of 32 months of follow-up in the DES group.)

Brilakis, ES, Lichtenwalter, C, Abdel-karim, A-rR. "Continued benefit from paclitaxel-eluting compared with bare-metal stent Implantation in saphenous vein graft lesions during long-term follow-up of the SOS (Stenting of Saphenous Vein Grafts) trial". J AM Coll Cardiol Intv. vol. 4. 2011. pp. 176-82.

(Stenting Of Saphenous Vein Grafts trial [SOS] trial: first multicenter randomized-controlled trial of DES [paclitaxel-eluting] in SVGs [80 patients] showing angiographic and clinical benefit with DES during short and long-term follow-up.)

Mehilli, J, Pache, J, Abdel-Wahab, M. "Drug-eluting versus bare-metal stents in saphenous vein graft lesions (ISAR-CABG): a randomised controlled superiority trial". Lancet. vol. 378. 2011. pp. 1071-8.

(Is Drug-Eluting-Stenting Associated with Improved Results in Coronary Artery Bypass Grafts? [ISAR-CABG) trial: largest [610 patients) randomized-controlled clinical trial of DES [sirolimus- and paclitaxel-eluting) in SVGs and the only trial with a clinical primary endpoint. It showed significant reduction in the need for repeat revascularization with DES compared to bare metal stents [7% vs. 13%, P = .01) with similar rates of death and myocardial infarction at 12 months.

Farooq, V, Mamas, MA, Fath-Ordoubadi, F, Fraser, DG. "The use of a guide catheter extension system as an aid during transradial percutaneous coronary intervention of coronary artery bypass grafts". Catheter Cardiovasc Interv. vol. 78. 2011. pp. 847-63.

(Large case series describing the use of guide catheter extensions for facilitating SVG interventions via the transradial approach.)

Roffi, M, Mukherjee, D, Chew, DP. "Lack of benefit from intravenous platelet glycoprotein IIb/IIIa receptor inhibition as adjunctive treatment for percutaneous interventions of aortocoronary bypass grafts: a pooled analysis of five randomized clinical trials". Circulation. vol. 106. 2002. pp. 3063-7.

(Meta-analysis of five randomized-controlled trials of glycoprotein IIb/IIIa inhibitors showing no benefit in patients undergoing SVG intervention.)

Brilakis, ES, Rao, SV, Banerjee, S. "Percutaneous coronary intervention in native arteries versus bypass grafts in prior coronary artery bypass grafting patients: a report from the national cardiovascular data registry". JACC Cardiovasc Interv. vol. 4. 2011. pp. 844-50.

(Analysis from the National Cardiovascular Data Registry showing that patients with prior CABG who undergo native coronary artery intervention have better in-hospital outcomes compared to patients who undergo bypass graft interventions.)

Levine, GN, Bates, ER, Blankenship, JC. "2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention. A report of the American College of Cardiology Foundation/American Heart Association task force on practice guidelines and the Society for Cardiovascular Angiography and Interventions". J Am Coll Cardiol. vol. 58. 2011. pp. e44-122.

(2011 ACC/AHA PCI guidelines. Main recommendations regarding SVG interventions are: [1] embolic protection devices should be used if technically feasible [class I recommendation]; [2] glycoprotein IIb/IIIa inhibitors are not beneficial in SVG interventions [class III recommendation); [3] PCI is not recommended for SVG chronic total occlusions (class III recommendation); [4] use of drug-eluting stents is beneficial in SVGs for reducing the need for repeat revascularization if the patient is likely to be able to tolerate and comply with prolonged with dual antiplatelet therapy [class I recommendation]).
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