Embolic ProtectionDevices in Saphenous Vein Graft Interventions: Is There Still a Role?

Saphenous vein grafts (SVG) are commonly used conduits for coronary bypass, with a graft failure rate of up to 45% per patient and 29% per graft on angiographic follow-up at 18 months.¹ Atherosclerotic plaques in SVGs tend to be bulky, friable, lipid-rich, and less calcified compared to atherosclerosis in native arteries. Percutaneous intervention in SVGs carries an early as well as late increase in the risk of major adverse cardiac events, resulting from distal microembolization, vasospasm of the distal vascular bed, and microvascular plugging.²

In this issue of the Journal of Invasive Cardiology, Golwala et al describe their retrospective, single-center experience with the use of embolic protection devices (EPD) as well as early and 1-year outcomes in SVG interventions.³ EPDs, developed in an effort to reduce atheroembolic events, can be categorized into proximal or distal occlusion-aspiration systems and filter devices. The National Cardiovascular Data Registry demonstrates an EPD utilization rate of 22% against an approximately 50-60% suitability for use of EPDs based on retrospective studies.^4-6 Golwala et al report an EPD utilization rate of 43.4% over 5 years in this retrospective study.

Periprocedural MI and no reflow are associated with long-term morbidity and mortality.⁷ SAFER was the first and only randomized multicenter trial designed to evaluate the benefit of an EPD (Guardwire) compared to a conventional coronary wire in elective SVG interventions. The study reported a 42% relative reduction in 30-day major adverse cardiac events (death, myocardial infarction [MI] and target vessel revascularization [TVR]), primarily driven by reduction in periprocedural MI.⁸ Golwala’s study noted no significant difference in the primary endpoint of  periprocedural MI, but a decrease in the composite endpoint of death, MI, and TVR at 1 year in the EPD (+) group compared to EPD (-) group. The lack of mortality benefit has been consistent with other reports, including the NCDR registry. In contrast to the findings in the SAFER study, the authors report that MI was not significantly affected by the use of EPD. The retrospective nature of the study allows for selection bias, and as reported by the authors, the lack of availability of angiographic data — plaque volume, lesion length, graft degeneration score, and reference vessel diameter — could explain these results. Furthermore, the authors did not specify the location of the lesions included in the study. This is important since proximal and distal anastomotic lesions, and in-stent restenosis lesions are less prone to distal embolization as compared to de novo lesions in the body of the graft. The authors did not clearly define periprocedural MI in patients already presenting with MI, who comprise almost 30% of the study population, which could have a confounding effect on the results.

Interestingly, the study reports improvement in the 1-year combined endpoint of death, MI, and TVR, mainly driven by reduction in TVR. This difference in TVR is not consistent with previous studies, and the authors provide no explanation for it.

SVG intervention carries a higher risk of early and late cardiovascular events. Despite improvements in periprocedural MI and no reflow with EPD use, there is no clear mortality benefit demonstrated either in SAFER or the NCDR registry.^4,8 In this study by Golwala et al, there was no difference in the primary endpoint of periprocedural MI, but a reduction in the combined endpoint of death, MI, and TVR at 1 year. Although the data are conflicting, there continues to be a good argument for the use of EPD during SVG intervention, even with improvement in the adjunctive pharmacotherapy during PCI, as stated in the guidelines. Technical limitations and operator inexperience play a significant role in the poor utilization of EPD seen across many data sets. Long-term outcomes with EPD use in SVG intervention are still lacking.

References

1. Alexander JH, Hafley G, Harrington RA, et al. Efficacy and safety of edifoligide, an E2F transcription factor decoy, for prevention of vein graft failure following coronary artery bypass graft surgery: PREVENT IV: a randomized controlled trial. JAMA. 2005;294(19):2446-2454.
2. Goldman S, Zadina K, Moritz T, et al. Long-term patency of saphenous vein and left internal mammary artery grafts after coronary artery bypass surgery: results from a Department of Veterans Affairs Cooperative study. VA Cooperative Study Group. J Am Coll Cardiol. 2004;44(11):2149-2156.
3. Golwala H, Hawkins, BM, Stavrakis S, Abu-Fadel MS. Embolic protection device use and outcomes in patients receiving saphenous vein graft interventions — a single-center experience. J Invasive Cardiol. 2012;24(1):1-3. 
4. Mehta SK, Frutkin AD, Milford-Beland S, et al. Utilization of distal embolic protection in saphenous vein graft interventions (an analysis of 19546 patients in the American College of Cardiology-National Cardiovascular Data Registry). Am J Cardiol. 2007;100(7):1114-1118.
5. Mathew V, Lennon RJ, Rihal CS, et al. Applicability of distal protection for aortocoronary vein graft interventions in clinical practice. Catheter Cardiovasc Interv. 2004;63(2):148-151.
6. Webb LA, Dixon SR, Safian RD, et al. Usefulness of embolic protection devices during saphenous vein graft intervention in a nonselected population. J Interv Cardiol. 2005;18(2):73-75.
7. Resnic FS, Wainstein M, Lee MK, et al. No-reflow is an independent predictor of death and myocardial infarction after percutaneous coronary intervention. Am Heart J. 2003;145(1):42-46.
8. Baim DS, Wahr D, George B, et al. Randomized trial of a distal embolic protection device during percutaneous intervention of saphenous vein aorto-coronary bypass grafts. Saphenous vein graft Angioplasty Free of Emboli Randomized (SAFER) Trial Investigators. Circulation. 2002;105(11):1285-1290.

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From the Division of Cardiology, University of Cincinnati College of Medicine, Cincinnati, Ohio.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.
Address for correspondence: Tarek Helmy, MD, FACC, FSCAI, Professor of Medicine, Division of Cardiology, Director of Cardiac Catheterization Laboratory, University of Cincinnati College of Medicine, Cincinnati OH, 45243. Email: helmyta@ucmail.uc.edu