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Bypass Graft – Case 1

Clinical Presentation

  • 73-year-old male who presented with chest pain (CCS Class IV).

Past Medical History

  • HTN, HLD, CAD s/p 3-Vessel CABG and Multiple PCI’s, Thyroid Cancer s/p Radiation Therapy, Pancreatitis
  • LVEF 45%

Clinical Variables

  • Stress MPI: Large size, severe perfusion defect involving the inferior wall.

Medications

  • Home Medications: Aspirin, Atorvastatin, Metoprolol Succine, Amlodipine, Isosorbide Mononitrate, Losartan, Levothyroxine, Esomeprazole
  • Adjunct Pharmacotherapy: Clopidogrel, Bivalirudin

Pre-procedure EKG

Angiograms

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Left coronary artery angiography
  • 80-90% calcified lesion in the proximal left anterior descending (LAD)
  • 80-90% stenosis in the first diagonal branch (D1).
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Left coronary artery angiography

  • 80-90% calcified lesion in the proximal left anterior descending (LAD)
  • 80-90% stenosis in the first diagonal branch (D1).
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2 of 10

Right coronary artery (RCA) angiography

  • total occlusion of the RCA.
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Angiography of the saphenous vein graft (SVG) to the ramus intermedius (RI)

  • no obstruction.
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Angiography of the SVG to D1

  • 80-90% thrombotic lesion.
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Angiography of the LIMA to LAD bypass graft

  • no significant disease
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Positioning of an Xience Alpine 3.5/33mm stent in the SVG-D1 with use of a Guideliner extension catheter.

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7 of 10

Deployment of an Xience Alpine 3.5/33mm stent in the SVG-D1 bypass graft.

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Angiography of the SVG-D1 after placement of a stent showing slow flow (TIMI 1).

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Intra-graft (IG) vasodilators were administered through the guide catheter. Angiography showing restoration of flow (TIMI 3).

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Despite restoration of flow, patient continued to have refractory chest pain with EKG showing diffuse ST-T wave changes, and an intra-aortic balloon pump (IABP) was placed.

Post-procedure EKG

Case Overview

  • Underwent intervention of the SVG to D1 bypass graft.
  • SVG was directly stented with procedure being complicated by slow flow.
  • Intra-graft vasodilators were given with restoration of flow.
  • Patient continued to have refractory chest pain with EKG showing diffuse ST-T wave changes, and an IABP was placed.
  • Troponin-I peaked at 7.91 ng/mL and CK-MB peaked at 23.7 ng/mL.
  • Patient was discharged 3 days later without further sequelae.

Learning Objectives

  • What is the likely explanation or reason why the complication occurred?
    • SVG’s which are of older age (usually >2 years since the time of implantation), degenerative, or with severe plaque burden are more predisposed to extensive thrombotic burden and distal embolization during coronary graft interventions, resulting in no-reflow phenomenon and periprocedural MI.
  • How could the complication have been prevented?
    • Embolic protection devices (EPDs) should be used during a SVG intervention when technically feasible (AHA/ACC class 1 recommendation).
    • Avoid pre-dilatation and post-dilatation of vein graft lesions as much as possible. Severe stenosis may require SVG lesion pre-dilatation with a small balloon to facilitate delivery of devices, a stent should be sized one to one, and high pressure inflation should be avoided (balloon inflation pressure should be kept <16 atm) to prevent a “cheesegrater” effect, increasing risk of distal embolization of debris/thrombi.
    • Assure patient is given adequate antithrombotic therapy (antiplatelets and anticoagulants).
      • Anticoagulants used in SVG interventions include heparin or bivalirudin (lower risk for bleeding complications).
      • Glycoprotein IIb/III inhibitor administration has not been shown to provide benefit in SVG interventions and should not be used (class III recommendation in the 2011 ACC/AHA PCI guidelines).
  • Is there an alternate strategy that could have been used to manage the complication?
    • The initial step in management of slow flow/no-reflow in a vein graft involves administration of intra-graft vasodilators through the guide catheter. If this fails it is recommended to use a dual-lumen microcatheter (Twinpass is the only dual lumen microcatheter available in the USA) to deliver intra-coronary medications to the native distal vessel and microvasculature.
    • If slow flow/no-reflow occurs during intervention using a EPD, then perform aspiration thrombectomy to clear the debris obstructing the filter. If this fails, the filter should likely be removed to restore antegrade flow, and if further intervention is required a new filter should be placed prior to proceeding forward with intervention.
  • What are the important learning points?
    • EPDs have been shown to be beneficial in SVG interventions but not in native coronary artery interventions.
      • Currently, there are 3 types of EPDs: the distal balloon occlusion/aspiration system; distal filter system; and the proximal occlusion/aspiration system.
        • Distal occlusion/aspiration system. SAFER trial showed a remarkable 42% reduction in 30-day MACE and a marked decrease in the no-reflow phenomenon with utilization of EPD (PercuSurge GuardWire system). TriActiv system was proven to be noninferior to the GuardWire system in the PRIDE trial.
        • Distal filtration system. FIRE trial showed noninferiority of the FilterWire EX System to the GuardWire system. BLAZE I and II study showed decease in MACE with the FilterWire EZ, and SPIDER trial showed noninferiority of the Spider Rx filtration device to GuardWire and FilterWire. AMEthyst trial showed the Interceptor PLUS device to be noninferior to the GuardWire and FilterWire EZ.
        • Proximal occlusion/aspiration system. PROXIMAL trial showed the Proxis system to be noninferior to distal EPD’s.
      • Location of the stenosis determines the type of EPD that may be utilized.
        • Ostial lesions require a distal EPD as proximal device use is contraindicated.
        • Lesions in the body of the graft can be served either by a proximal or distal device.
        • Distal lesions can only be proximally protected.
      • Embolic protection should be used in all SVG interventions with the following exceptions:
        • ISR lesions, which are composed of fibrous tissue and have low embolization risk
        • Recently implanted (<2 year-old SVG, that have not had enough time to develop significant degeneration predisposing to embolization
        • 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).
      • The best treatment for slow flow/no-reflow is to prevent it from happening.
      • The exact mechanism of the no-reflow phenomenon is unclear, but it is thought to be associated with endothelial swelling, neutrophil infiltration, and platelet aggregation causing obstruction and spasm in the microvasculature.
      • Important to have multiple vasodilators readily available during a procedure. We use the following agents and administer them intra-graft.
        • Nitroprusside 50-200 mcg, Adenosine 30-40 mcg, Verapamil 100-200 mcg, Nicardipine 100-200 mcg
        • Nitroglycerin 100-200 mcg (we use NTG for slow flow/no-reflow when it involved the epicardial vessels and not the coronary microvasculature)
      • If the patient is hypotensive and this impedes the administration of intra-coronary or intra-graft vasodilators to treat slow flow/no-reflow, we recommend administration of IV phenylephrine 100-200 mcg as needed (may result in reflex bradycardia) to increase blood pressure, and then administer intra-coronary/intra-graft vasodilators.
      • If there is refractory slow flow/no reflow then consider placement of an IABP. This helps with reduction in afterload, and improves coronary perfusion pressure by increasing coronary blood flow during diastole, and reduction in LVEDP.
      • Additional stent implantation should not be performed until normal antegrade flow is restored.
Educational Content

BYPASS GRAFT COMPLICATIONS

Coronary artery bypass graft procedure is usually performed in severe three-vessel disease or two vessels with a left main disease using arterial or vein grafts. The grafts' longevity varies depending on many factors, including the quality of the grafts, underlying comorbidities, and surgical techniques. However, saphenous vein grafts (SVGs) are prone to degeneration and occlusion, leading to poor long-term patency compared with arterial grafts with ~ 10−25% of SVGs failure within the first year after CABG surgery 1,2 and late graft failure at ≥ten years is 40 -50%.3 Hence, PCI of the native artery should be the preferred approach whenever feasible as interventions in degenerative SVG disease, type C lesion per AHA classification, are prone to have higher peri-procedural complications.

Common Complications associated with percutaneous intervention of bypass grafts are:

  • Slow flow/ no-reflow
  • Peri-procedural myocardial infarction

Slow flow/No-reflow

It is a common complication of degenerative graft intervention and can be preventable/treatable if the appropriate treatment steps are followed.

Incidence: 10-15% cases of percutaneous intervention (PCI) in aortocoronary saphenous vein grafts (SVG).

Prevention:
  • Optimal anticoagulant and antiplatelet therapy
  • Ensure to obtain optimal guiding-catheter support
  • Consider aspiration thrombectomy in a setting of heavy thrombus burden
  • Avoid pre and post dilation if possible
  • Direct stenting strategy if feasible
  • Use of embolic protection devices(EPD) whenever technically feasible

Treatment:
  • Ensure to keep the optimal blood pressure (SBP > 100Hg) and give fluids, vasopressors, and pacing as needed
  • Administer intracoronary vasodilators, such as adenosine, nitroprusside, nitroglycerin, nicardipine, and verapamil administered distally in the vessel if necessary, via a dual-lumen microcatheter (Twin-pass catheter)
  • If EPD is used, consider to use aspiration thrombectomy to clear debris from the filter first, then remove the filter if necessary. New filter can be placed if needed.
  • If hemodynamically unstable, place an intra-aortic balloon pump to augment coronary perfusion pressure

Peri-procedural Myocardial infarction

The risk of developing CK-MB elevation is relatively higher during saphenous vein graft (SVG) than native coronary intervention, probable due to more friable atherosclerotic or thrombotic components of the SVG lesions.5

Incidence: 15% of patients who underwent SVG intervention were found to have CK-MB levels >5x the upper limit of normal (ULN).6

Prevention:
  • Avoid pre-dilation with balloon angioplasty
  • Use Direct stenting strategy whenever possible (direct stenting were associated with nearly a 50 % reduction in CK-MB level elevations >4x normal)7
  • Appropriate stent sizing
  • Avoid high pressure balloon inflation with maximum inflation pressures of 12-14 atm.
  • Adequate use of anticoagulant and antiplatelet therapy
  • Use of Embolic protection devices whenever possible

Treatment:
  • Use of post PCI optimal antiplatelet therapy (Dual antiplatelets) if there is no contraindication
  • Use of coronary vasodilators if there is slow flow/no-reflow phenomenon
  • Consider to use oral coronary vasodilators and beta blocker if residual chest pain presents
  • Optimize medical therapy for underlying comorbidities



References

  1. Hess, C. N. et al. Saphenous vein graft failure after coronary artery bypass surgery: insights from PREVENT IV. Circulation 130, 1445–1451 (2014).
  2. Fitzgibbon, G. M. et al. Coronary bypass graft fate and patient outcome: angiographic follow-up of 5,065 grafts related to survival and reoperation in 1,388 patients during 25 years. J. Am. Coll. Cardiol. 28, 616–626 (1996).
  3. Caliskan E, de Souza DR, Böning A, et al. Saphenous vein grafts in contemporary coronary artery bypass graft surgery. Nat Rev Cardiol. 2020;17(3):155-169. doi:10.1038/s41569-019-0249-3
  4. Piana RN, Paik GY, Moscucci M, Cohen DJ, Gibson CM, Kugel-mass AD, Carrozza JP Jr, Kuntz RE, Baim DS. Incidence and treatment of “no-reflow” after percutaneous coronary intervention.Circulation 1994;89:2514–2518.
  5. Abdelmeguid AE, Topol EJ, Whitlow PL, Sapp SK, Ellis SG. Significance of mild transient release of creatine kinase-MB fraction after percutaneous coronary interventions. Circulation.1996; 94:1528–1536.
  6. Hong MK, Mehran R, Dangas G, et al. Creatine kinase-MB enzyme elevation following successful saphenous vein graft intervention is associated with late mortality. Circulation 1999;100:2400–5.
  7. Leborgne L, Cheneau E, Pichard A, et al. Effect of direct stenting on clinical outcome in patients treated with percutaneous coronary intervention on saphenous vein graft. Am Heart J 2003;146:501–6.

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