Bypass graft intervention2

Bypass Graft Intervention
Dr Virbhan Balai
Interventional Cardiologist
FNB,DNB,MD,DLO,MBBS

General Considerations in SVG PCI
1) Give preference to PCI of the native coronary if feasible, particularly if the SVG
graft is degenerated.
2) Avoid balloon predilatation unless the lesion is severely stenotic or if required for
the delivery of an EPD.
3) Consider EPD whenever technically feasible.
4) Utilize microvascular vasodilators liberally, even before balloon
angioplasty/stenting.
5) Avoid post-dilatation.
6) If post-dilatation is performed, size the balloon 1:1 with the graft.
7) Perform slow and prolonged stent and balloon inflation at nominal pressures.
8) Consider slightly undersized stent but a longer stent length to reduce plaque
extrusion through stent struts.
9) Consider thrombectomy in lesions with a heavy thrombus burden.
10) Keep ACT on the higher side.
11) Consider prolonged DAPT based on the DAPT score, as SVG PCI is considered
high-risk for ischemic events.

BYPASS GRAFT INTERVENTION
Early postoperative ischemia (<30 days) is
frequently due to graft occlusion or stenosis.
USA or STEMI years after CABG is most often
due to a SVG lesion; in such cases, native vessel
PCI is preferred whenever possible.
EPDs reduces the risk of atheroembolic MI during
SVG PCI and should be used in the Tt of most de
novo SVG lesions that occur years after CABG.

 Redo CABG-: Multiple diseased or occluded
SVGs, ↓ LV function, and available arterial
conduits favor repeat CABG.
Patent LIMA to the LAD coronary artery favors
PCI.
DESs reduce restenosis in native coronary arteries
and have become the default strategy in SVGs for
many operators in spite of reduced efficacy in
SVGs compared with native vessels.
Five randomized trials of DESs and BMSs in
SVGs yielded conflicting results.

THE SCOPE OF THE PROBLEM
Severe myocardial ischemic syndromes occur in
3- 5% of pts immediately after surgery; thereafter,
recurrent ischemic symptoms appear in 4- 8% of
Post-CABG pts annually.
SVG attrition, the most common cause, is up to
40% during the first year; 1% to 2% of grafts
occlude annually 1 to 5 years after surgery, and
5% occlude each year over the next 5 years.
At 10 years, one half of all SVGs are occluded,
and half of the patent SVGs are diseased.

For reoperation, even in the most experienced centers,
the risk of in-hospital death and nonfatal Q-wave MI is
triple that of the initial operation.
In the state of New York, in-hospital mortality was
4.1% for initial operations but 11%, 25%, and 39% for
first, second, and third reoperations, respectively.
In addition to being more risky, reoperative surgery was
associated with less complete anginal relief and
reduced graft patency.
These factors have promoted a conservative approach
to reoperation and have favored the use of PCI.

INDICATIONS FOR INTERVENTION
Recurrent ischemia after CABG
Status of the LAD and its graft significantly
influences revascularization choices bcz of lack of
survival benefit of reoperative surgery to treat
non–LAD related ischemia.
Factors that favor surgical revascularization
include multiple-vessel involvement, severe vein
graft disease, poor LV function, total occlusions
of native coronary arteries, and the availability of
arterial conduits.

Early Postoperative Period
In a randomized trial in over 100 high-volume
U.S. centers that included over 3000 pt`s in
whom modern surgical techniques and
medications were utilized, graft failure at 1
year occurred in 41.6% of SVGs with a single
distal anastomosis and 50.6% with multiple
distal anastomoses.
– PREVENT IV Trial. Circulation. 2011;124:280–288

 PRAGUE-4 (randomized comparison b/w off-pump and on-pump surgery)
trial, angiographic follow-up at 1 year revealed that 40% of SVGs and 9%
of LIMA grafts were occluded.
 Circulation. 2004;110:3418–3423.
 In the Veterans Affairs Randomized On/Off Bypass (ROOBY) study, 23%
of SVGs and 11% of LIMA grafts performed off-pump failed at 1 year.
 N Engl J Med. 2009;361:1827–1837.
 In the DACABG trial conducted in 2014 to 2015, pts undergoing elective
CABG and treated with aspirin postoperatively experienced a 24% rate of
SVG failure.
 JAMA. 2018;319(16):1677–1686.
 Graft failure was associated with death, new MI, or repeat revascularization
in 26% of patients.
 Recurrent ischemia within days of surgery is usually related to acute vein
graft thrombosis due to endothelial damage during harvesting and initial
exposure to arterial pressure.

PCI in pt`s with early ischemia after CABG is
a class I indication in the ACC/AHA/SCAI
PCI guidelines and the European guidelines on
revascularization.
• Eur Heart J. 2010;31:2501–2555.

 European guidelines advise against PCI of a graft anastomosis early
after CABG because of this risk of perforation.
 Eur Heart J. 2010;31:2501–2555.
 Mild to moderate imperfections at the anastomosis observed in the
early postoperative period should not be dilated because they
frequently disappear on subsequent angiography, suggesting the
presence of edema.
 If a thrombosed graft is discovered, PCI of the native coronary
artery is recommended, but mechanical thrombectomy can be
attempted—or a return to the operating room may be considered—if
the jeopardized vessel is of significant importance.

When ischemia recurs 1- 12 months after
surgery, perianastomotic stenoses are among
the most common problems.
Stenotic lesions of the distal anastomosis of
SVG or arterial grafts can be successfully
dilated with balloon angioplasty at this time
with little morbidity and good longterm
patency in 80- 90% of pts without stent
implantation.

Sites of saphenous vein graft stenoses
All lesions b/w the proximal and distal anastomoses are considered midgraft lesions.

One to Three Years After Surgery
Whenever possible, native coronary lesions are
targeted.
ACC/AHA/SCAI PCI guidelines consider
focal ischemia–producing graft lesions in pts
1- 3 yrs after CABG with preserved LV
function to be a class IIa indication.
J Am Coll Cardiol. 2006;47:1–121.

> 3 Years After Surgery
>3 yrs, atherosclerotic lesions appear in vein
grafts with increasing frequency.
~70% of post-CABG pts presenting with ACS,
the culprit lesion is in SVG.
Atherosclerotic plaques in vein grafts contain
foam cells, cholesterol crystals, blood
elements, and necrotic debris, with less
fibrocollagenous tissue and calcification than
are present in native coronary arteries.

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 thin fibrous caps and
associated thrombus formation.

OCT studies of older SVGs in pts with stable
angina surprisingly documented the presence
of thrombus in most pts and in pts with ACSs
revealed the enormous complexity of SVG
lesions

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.
Improved initial outcome has been reported with
stent placement compared with balloon dilation in
SVGs.
However, long-term results in SVGs have been
disappointing.

Acute STEMI
After CABG, approx 3% of pt`s experience
STEMI annually.
In a majority of pts, the culprit vessel has been
found to be a vein graft, and considerable
lesion-associated thrombus.
I/V thrombolytic therapy is relatively
ineffective in SVGs.
Am J Cardiol. 1990;65:1292–1296.

Recent reports indicate that both acute and
long-term results of PCI in SVGs for Tt of
STEMI are inferior to those of native vessel
PCI for STEMI.

Pts who underwent SVG PCI were sicker (had
poorer LV function, more TVD, and prior MI)
than pts who underwent native vessel PCI.
Catheter Cardiovasc Inter. 2005;65:504–509.
Pts with SVG occlusion had lower rates of
TIMI grade 3 blood flow, higher in-hospital
mortality (21% vs. 8%, P = .0004), and worse
10-year survival (49% vs. 76%, P < .0001).
SVG patency was 64% at 1 year.

ACC/AHA Task Force Report on Early
Management of Acute MI classified PCI for
vein graft recanalization as a class IIa
intervention.
• J Am Coll Cardiol. 1996;28:1328–1428.

Selection of guide
catheters in vein graft
angioplasty:
a. Multipurpose shape;
b. Multipurpose, JR;
c. Hockey stick, AL, JR;
d. Hockey stick, AL.
Obtaining adequate backup
becomes more difficult in
positions c and d.

For far distal lesion (LIMA or SVG), balloon
catheters with extra-long (145- cm) shafts or
shorter GC (80- 90 cm) may be needed, or GC
can be shortened and a flared, short sheath one
size smaller can be used to close the cut end of
the catheter.
EPD- Class I/B (ACC/AHA 2011), IIA (ESC
2018) for PCI of de novo SVG lesions.

RESULTS OF INTERVENTION
 PCI Vs REOPERATION
 At Emory University over a fourteen year period, total of
2613 post CABG pts underwent PCI, Compared with 1561
pts treated with reoperative surgery; in-hospital outcomes
were more favorable in PCI group, for mortality (1.1% vs.
6.9%; P < .001), Q-wave MI (1.4% vs. 5.4%; P < .001),
stroke (0% vs. 2.8%; P = .27), length of stay (3.0 vs. 10.5
days; P < .001) and cost ($8500 vs. $24,200; P < .01).
• Circulation. 1997;95:868–877.
 Ten-year survival was better in the angioplasty group.
 By 5 years, approx 50% of the PCI pts required either
repeated PCI or CABG, and survival was better in pts who
underwent native vessel, compared with graft, interventions.

In 2191 post- CABG pts who underwent
multivessel revascularization at the Cleveland
Clinic between 1995 and 2000, a total of 1487
had reoperation and 704 had PCI.
Initial outcomes were more favorable with PCI
for completeness of revascularization, 30-day
mortality, periprocedural Q-wave infarction, and
stroke.
At 5 years, unadjusted survival was 79% for
CABG and 75% for PCI (P =.008).

The only randomized comparison of PCI and
CABG in post-bypass pts was reported by
Morrison and colleagues, who randomized 143
pts (67 to PCI and 75 to CABG).
At 3 years, survival was approx 75% in both
groups.

Vein Graft Intervention
Guideline and AUC encourage PCI in early graft
failure but are less supportive of PCI in vein
grafts >3 yrs bcz of the risk of embolic MI and
poor durability.
Indication Vein graft intervention: Class IIa, for
pts with sev symptoms, good LV function, and
patent arterial grafts,, and for pts who are poor
candidates for surgery.
SVG PCI was appropriate in pts with stable class
III or IV symptoms or intermediate to high risk
findings on non invasive testing.

Determining physiologyical significance of
vein graft lesion - similar to those for native
vessel lesions, but FFR has not been well
studied in this setting.
Bcz progression of atherosclerosis in SVGs
exceeds that in native coronary arteries, some
operators have been more aggressive in SVGs.
However, PCI of moderate nonobstructive
stenosis in SVGs is not supported as of now.

BMS Vs Balloon Angioplasty in Vein
Grafts
Restenosis occurred in 68% of proximal
lesions, 61% of midvein graft lesions, and 45%
of distal lesions.
These relatively poor results of balloon
angioplasty in SVGs prompted use of BMSs.

DES in Vein Grafts
Published reports of the use of DESs in SVGs
have shown conflicting results.
Five randomized comparisons of DESs with
BMSs in SVGs have been reported involving a
total of 1535 pts.
Two reported benefits, one harm, and two
equal outcomes.

ISAR-CABG study, is the first powered for
clinical end points.
In this superiority trial, 610 pts were randomly
assigned to receive BMS or DESs.
Primary end point: Combined incidence of
death, MI, and TLR- was reduced significantly
at 1 year by DES use (15% vs. 22%, P = .02),
as was TLR (7% vs. 13%, P =.01).

Clinical Results at 5 Years in ISAR-CABG

1. The GuardWire system (Medtronics, Minneapolis, MN
[no longer available]) .
Saphenous Vein Graft Angioplasty Free of Emboli
Randomized (SAFER) trial - 801 pt`s were randomly
assigned to stent implantation with or without use of
the GuardWire distal protection device.
This study is the only RCT of EPD vs no protection.
30day MACEs were reduced by 42% with use of EPD
(16.5% to 9.6%, P = .004), primarily bcz of the lower
rates of MI.

Disadvantages GuardWire system EPD
– Completely occlude the target SVG during stent
deployment and aspiration (not always well
tolerated),
– Requirement for a relatively long “parking” seg
distal to the lesion,
– Inability to protect SB,
– Complexity of the system
– Added procedural time, cost, and potential for
complications.

2. Filters have become the only form of EPDs
currently available.
In a 651-pts randomized multicenter trial, the
FilterWire (Boston Scientific, Natick, MA) was
compared with the GuardWire.
30-day MACE rate, the primary end point, was
similar—9.9% with the FilterWire compared with
11.6% with the GuardWire—and no difference
was seen in rates of death or MI.
• Circulation. 2003;108:548–553.

• Advantages of filters include
– Ease of use
– Avoidance of ischemia bcz of preserved coronary
flow.
– Good visualization of the site to be stented.
• Disadvantages
– Need to cross the lesion with a somewhat bulky
filter, which may require predilation and could
cause embolization.

3. Proximal protection device- applicable in pts
with an inadequate “landing zone” beyond the
lesion,, is no longer available.

Variables found to be potent predictors of 30-
day MACEs.
– SVG degeneration score
– Large estimated plaque volume
– Thrombus
– Advanced patient age
– Active tobacco

Clinical scenarios in which EPD may be
expected to have little impact-
– Lesions with very little plaque volume.
– ISR lesions in which neointimal hyperplasia is the
predominant pathology.
– Lesions that occur < 3 yrs after CABG.

Strategies to mitigate atheroembolization risk-
Direct stenting, Slight stent undersizing, use of
Longer stents, and use of EPDs (filters).
Use of filters during stent implantation in
ostial SVG lesions has been associated with
serious complications due to difficulty in filter
retrieval.

Adjunctive Pharmacotherapy
Aspirin, antithrombin, other antiplatelet
agents.
UFH.
Optimal dosing and dur. of DAPT following
SVG PCI -not well studied.
600 mg of clopidogrel prior to SVG PCI, f/b
75 mg daily for at least a year.

5-year event rate was lowest in pts treated with
clopidogrel for >2 years (P < .001), which
supports long-term DAPT following SVG PCI.
J Am Coll Cardiol. 2012;60:2357–2363.
Large embolic burden in SVG - failure of GP
IIb/ IIIa platelet receptor inhibitors to prevent
periprocedural MI in these pts.

In spite of the class III recommendation in the
2011 PCI guidelines for the use of GP IIb/IIIa
inhibitors in SVG PCI, selective use in certain pts
with significant thrombus burden may be
indicated.
The use of microvascular dilators to treat no or
slow reflow following PCI, or their use
prophylactically before the procedure, has not
been well studied but is an important strategy in
SVG PCI.

Restenotic lesion in SVGs
Tt of ISR lesions in SVGs is safer than Tt of de
novo SVG lesions primarily bcz of reductions in
slow or no reflow and periprocedural MI and
reductions in dissection.
ISR lesions are a subset in which embolic
protection can often be omitted bcz the pathology
is mostly neointimal hyperplasia.
Intracoronary brachytherapy- gamma radiation
with Iridium-192.
DESs - default strategy in spite of a paucity of
data.

Total Occlusion of SVGs
In the setting of STEMI and newly formed
thrombus, results are suboptimal and as acuity
wanes, thrombus resistance heightens, making
PCI extremely challenging.
In the subacute setting, thrombectomy (aspiration
or rheolytic) with or without balloon angioplasty
plus a strategy to dissolve thrombus (local or
systemic GP IIb/IIIa or lytic agents, prolonged
anticoagulation) achieved reasonable initial
success in small cohort studies.

Delaying stent implantation for days or wks
until the thrombus burden had largely
resolved, use of EPD and undersized stents to
avoid the consequences of embolization.
Intervention in chronic total SVG occlusion:
class III recommendation in the 2011 PCI
guidelines.

Internal Mammary Artery Grafts
Favorable results have been reported with
balloon dilation of IMA graft stenoses. Lesions
at the anastomoses of arterial grafts with the
native coronary artery behave much like distal
anastomotic lesions of SVGs.
They usually occur within a few months of
surgery and often respond to low-pressure
balloon inflations.

Successful dilation and stenting of ostial or
extremely proximal IMA graft lesions is
infrequently required.
PCI of IMA graft lesions, 97% procedural
success and TLR of 7% at 1 year.
Complications were infrequent, the most
common being IMA dissection and spasm.

COMPLICATIONS
The most common complications are
atheroembolic MI, bleeding, no reflow, and graft
perforation.
Embolic MI is minimized by
– Avoide of bulky SVG lesions.
– Perform native vessel PCI.
– Using EPDs in SVGs when possible.
– using direct stenting.
– Slight stent undersizing.
– Avoide postdilation of stents in SVGs.

Perforation
Causes: vessel wall penetration with guidewires,
inflation of balloon in a subintimal location,
overexpansion of a coronary artery or graft,
atheroablative techniques, and stent implantation.
SVG perforation is a rare but greatly feared
complication.
Rx- : Prolonged balloon inflation and reversal of
anticoagulation are effective in stabilizing most
pts.

• Covered stents: - bcz of their large diameter,
SVGs are favorable conduits for use of this
strategy for sealing perforations.
• Size balloons and stents to the normal adjacent
vessel or slightly smaller.
• Plan ahead by having a covered stent of proper
size available and by using a guide catheter
capable of delivering the device.

No-Reflow Phenomenon
Multifactoral: - Vasospasm and embolization
of atheromatous debris and thrombus.
Microvascular spasm: - Vasoconstrictors are
released during SVG stent procedures.

CCBs, adenosine, nitroprusside
Lack of benefit of nitroglycerin- though
relieve spasm.
Aspiration of the stagnant dye column
retrieving plaque gruel, and soluble
vasoconstrictors liberated during SVG PCI
EPDs

Bypass graft intervention2

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