(Circulation. 1998;98:1591-1593.)
© 1998 American Heart Association, Inc.
Plaque Excision Combined With Stent Placement
Can a Poor "Finisher" Become a Good "Starter"?
Sheldon Goldberg, MD;
; Janah Aji, MD
From the University of Medicine and Dentistry of New Jersey, Cooper
Hospital/University Medical Center, Camden, NJ.
Correspondence to Sheldon Goldberg, MD, Director, Interventional Cardiology, Division of Cardiology, Department of Medicine, University of Medicine and Dentistry of New Jersey, Cooper Hospital/University Medical Center, One Cooper Plaza, Fourth Floor, Camden, NJ 08103.
Key Words: Editorials • plaque • stents
In an effort to
enhance long-term patency in the coronary circulation,
interventional cardiologists have examined the effects of a plethora of
devices designed to improve short-term results and reduce the
possibility of restenosis. Two disparate techniques, debulking
by means of directional coronary atherectomy (DCA) and
arterial scaffolding by stent implantation, have been
tested separately in prospective randomized trials with respect to
angiographic and clinical restenosis. In this issue of
Circulation, Moussa et al1 combine
plaque excision and slotted-tube stent placement in an attempt to show
that the 2 methods are synergistic.
DCA to Reduce Restenosis: A Tortured Season
DCA has been tested in several well-designed prospective,
randomized comparisons with balloon angioplasty. Two early studies,
CAVEAT and CCAT, showed that DCA applied to patients with focal lesions
in native coronary arteries resulted in only slight reductions
in the rate of restenosis. Specifically, in the CAVEAT trial,
in which 1012 patients were randomized to DCA or balloon
angioplasty,2 angiographic restenosis was
only slightly reduced, from 57% in the balloon group to 50% in DCA
group; clinical restenosis was unchanged (34% versus 35%). An
unexpected and disturbing finding was the excess mortality at 1 year in
the DCA group (2.2% for DCA versus 0.6% for PTCA,
P=0.035), a finding possibly attributable to the doubling of
periprocedural non–Q-wave infarction in patients treated with
atherectomy. In the CCAT trial,3 DCA was
performed in patients with isolated stenoses in the proximal
left anterior descending coronary artery, and results were
similar: a nonsignificant reduction in angiographic restenosis
(46% versus 43%) and no decrease in clinical restenosis
(30.1% versus 30.6%).
DCA was further evaluated in CAVEAT II, a trial in which 305 patients
with saphenous vein bypass graft stenoses were randomized to
either DCA or balloon angioplasty.4 Although
initial angiographic success was superior in the DCA arm, there was no
significant difference in either angiographic restenosis rates
(45.6% for DCA versus 50.5% for PTCA) or target reintervention
(18.6% for DCA versus 26.2% for PTCA, P=0.09).
Disturbingly, distal embolization, a serious complication of vein graft
intervention, was substantially higher in patients undergoing DCA
(13.4% for DCA versus 5.1% for PTCA, P=0.012). Although
death and Q-wave myocardial infarction were similar in both groups, the
rate of non–Q-wave myocardial infarction was higher in patients
assigned to atherectomy (16.1% for DCA versus 9.6% for PTCA,
P=0.09).
These disappointing results, along with the introduction of stents,
resulted in a dramatic reduction in the use of DCA by interventional
cardiologists, from 
15% of percutaneous
interventions to 1% to 2%. However, proponents of the technique
postulated that the unimpressive results obtained with DCA were due to
the premature performance of the randomized trials in a time
frame before operators had the opportunity to optimize the method with
more vigorous plaque excision. Accordingly, in the Optimal Atherectomy
Restenosis Study (OARS), 199 patients with new or
restenotic lesions in larger (3.0- to 4.5-mm) coronary
arteries had more aggressive debulking with the use of larger devices
(usually 7F cutters) intended to achieve <15% residual
stenosis, a goal that was achieved in 82% of
patients.5 The rate of major complications
(Q-wave myocardial infarction and CABG) was reasonably low at 2.5%,
but non–Q-wave myocardial infarctions, defined as CK-MB levels >3
times normal, occurred in 14% of patients. Angiographic
restenosis was 29%, and target lesion
revascularization was 18%, with postprocedure
lumen dimensions being a powerful predictor of the occurrence of
restenosis. At 1-year follow-up, there was 1 death 3 weeks
after the intervention in a patient without procedural complications or
CK-MB elevation. The concept of optimal atherectomy was formally tested
in the Balloon versus Optimal Atherectomy Trial (BOAT), in which 1000
patients with new lesions in native coronary arteries were
randomly assigned to undergo either DCA with aggressive tissue removal
(target residual stenosis <20%) or conventional
PTCA.6 Angiographic success was slightly better
with DCA, with a superior residual stenosis (15% for DCA
versus 28% for PTCA). Importantly, these results were achieved without
an increase in death, Q-wave MI, or emergency surgery: 2.8% versus
3.3%. However, the rate of CK-MB elevation >3 times normal was more
than twice as frequent: 16% for DCA versus 6% for PTCA
(P<0.001). Follow-up showed slightly less angiographic
restenosis (31% versus 40%) but no difference in target
vessel revascularization (17% versus 20%,
P=0.33).
In summary, the major DCA trials have shown a better initial
angiographic outcome but no long-term clinical benefit compared with
balloon angioplasty. The substantially higher incidence of CK-MB
elevation noted after DCA has raised concerns, because late mortality
at 3 years has been found to be increased in patients who experienced
these enzyme rises.7 To use a baseball analogy,
DCA used as the final technique has been an unsuccessful
"finisher."
Coronary Stent Implantation: A Long Winning Streak Against
Easy Teams
The publication of STRESS8 and
BENESTENT9 in 1994 marked a breakthrough in
attempts to reduce stenosis in relatively low-risk populations
(easy teams): those with new lesions in larger coronary
arteries. In these early randomized studies comparing the slotted-tube
Palmaz-Schatz stent with balloon angioplasty, the reduction in
angiographic restenosis from 42% to 32% (P<0.05)
in STRESS and from 32% to 22% (P<0.02) in BENESTENT was
accompanied by a reduced need for ischemia-driven target
revascularization at 6 months. These findings have
been extended and confirmed in a variety of patient populations. In a
randomized study of 120 patients with isolated stenoses of the
left anterior descending coronary artery, angiographic
restenosis was reduced from 40% to 19% (P=0.02),
and event-free survival at 1 year was improved from 70% to 87%
(P=0.04) by stent placement.10 In the
Saphenous Vein De Novo (SAVED) trial, 220 patients with lesions in aged
(10-year-old) saphenous vein grafts were assigned to coronary
stent implantation or balloon angioplasty. There was a trend toward
less angiographic restenosis, from 47% to 36%
(P=0.24), but event-free survival at 240 days was
significantly decreased, from 38% to 26% (P<0.04).
Remarkably, this was achieved with a lower rate of non–Q-wave
myocardial infarction: 11% for PTCA versus 6% for stents
(P=0.13).11 Subsequent studies in
which safe and effective antithrombotic regimens were used have
resulted in thrombosis rates of <1%, with low rates of bleeding and
vascular complications.12
Technological refinements have resulted in second-generation
slotted-tube stents, which are substantially easier to deliver to the
target site. Because of the ease of use, stenting has been applied to
broader patient populations (tougher teams) in whom restenosis
rates are not comparable to STRESS/BENESTENT-type
patients.13 This has resulted in a formidable new
challenge: the patient with in-stent restenosis. Although
target lesion revascularization rates in the 10%
range are achievable in patients with discrete new lesions in larger
coronary arteries, restenosis is significantly greater
in higher-risk patient populations, ie, those with longer
lesions,14 smaller
vessels,15 chronic total
occlusions,16 and restenosis and
diabetes. The mechanism of in-stent restenosis is a result of
intimal proliferation and matrix deposition, processes that thus far
have proved resistant to conventional transcatheter
technology. Although the use of local radiation seems to hold promise
in the therapy of patients with stent
restenosis,17 most would agree that
effective prevention of in-stent restenosis would be a
preferable approach. With 700 000 percutaneous
transluminal coronary intervention procedures being performed
annually in the United States, 60% of which are accomplished with
stent placement, most often in patients with non–STRESS/BENESTENT
lesions, in-stent restenosis has emerged as an important
clinical problem refractory to traditional therapeutic modalities.
Although the record of the stent is good, its statistics as a
"closer" might be improved with a better "opener."
Plaque Removal Followed by Stent Implantation
In this issue of Circulation, Moussa and
colleagues1 studied 71 patients in a prospective
registry to test the hypothesis that excision of plaque before stent
implantation would improve long-term patency beyond what is attainable
by stent placement alone. The study was performed in patients
undergoing elective intervention: two thirds of the patients had stable
angina, but lesion complexity was frequent in this group: half of the
stenoses were located at bifurcation points, and one third of
the lesions were nondiscrete (>15 mm in length). As expected,
clinical success was high, at 96%. One patient who required emergency
bypass surgery subsequently died. Q-wave infarction occurred in 2
patients (2.8%). Again, however, non–Q-wave myocardial infarction,
defined as elevation of cardiac enzymes to more than twice normal,
occurred in 8 patients (11.3%). Angiographic follow-up in 89% of
patients showed a remarkably low angiographic restenosis rate
of 10.7%, and target-vessel revascularization was
needed in only 6.7% of patients. The authors strengthen the validity
of the case for this combined approach by matching the patients in this
registry with patients who received only stents and had similar
clinical and angiographic characteristics. The improved acute
angiographic results—acute gain was 0.3 mm greater in the
DCA+stent group—was associated with a significantly lower loss index
(0.33 for DCA+stent versus 0.46 for stent alone, P=0.03).
This resulted in a significantly greater follow-up minimal lumen
diameter and less residual percent diameter stenosis. More
importantly, there was a trend toward a reduction in the need for
target lesion revascularization, from 18.7% for
stent alone to 6.7% (P=0.13) in the DCA+stent group. The
authors further demonstrated that the lowest loss index was found in
patients with low residual percent plaque area (<0.6). The basis for
this finding might be that less vessel wall stretch and consequently
less vessel wall injury occur if the coronary artery is
prepared for stenting by plaque removal. Because intimal hyperplasia is
directly related to the degree of vessel wall injury, a lower loss
index and greater long-term patency might be expected. Thus, it would
make intuitive sense to recast DCA in a new role: as the starter that
helps the stent (or "finisher") achieve an even better
record.
Clinical Implications and Future Directions
These thought-provoking findings should refocus our attention on
the possibility that long-term patency can be enhanced by refining the
technical aspects of our initial approach specifically by combining DCA
and stenting in a synergistic way. The inherent limitations of drawing
sweeping conclusions from pilot data will be addressed in a prospective
randomized trial, the Atherectomy before Multilink Improves Lumen Gain
and Clinical Outcomes (AMIGO) trial, in which excisional atherectomy
combined with stenting will be tested against stenting alone. In that
study, it is anticipated that 750 patients will be entered over a
6-month period. Patients with longer lesions (up to 32 mm) in
vessels with reference diameters of 2.75 to 3.5 mm will be
enrolled. Of note, difficult lesion subsets—ie, ostial and bifurcation
stenoses and chronic total occlusions—will be included. If the
strategy of debulking plus stenting proves superior to stenting alone,
we will need to dust off our idle cutters, retrain our
interventionalists, and give DCA another chance for a place in the sun,
but only as a "starter."
Footnotes
The opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.
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