Circulation. 1999;100:II-114-II-118
(Circulation. 1999;100:II-114.)
© 1999 American Heart Association, Inc.
Surgery for Coronary Artery Disease |
Isolated Left Anterior Descending Coronary Artery Disease
Percutaneous Transluminal Coronary Angioplasty Versus Stenting Versus Left Internal Mammary Artery Bypass Grafting
James H. OKeefe, Jr, MD;
Thomas R. Kreamer, MD;
Philip G. Jones;
James L. Vacek, MD;
Michael E. Gorton, MD;
Gregory F. Muehlebach, MD;
Barry D. Rutherford, MD;
Ben D. McCallister, MD
From the Mid America Heart Institute, Kansas City, Mo.
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Abstract
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BackgroundSingle-vessel
coronary artery disease is usually
treated with PTCA; however,
this approach when applied to the
left anterior descending
coronary artery (LAD) is hampered by
high restenosis
rates, often approaching 50%. Coronary stenting
(STENT) and
left internal mammary artery bypass grafting of
the LAD (LIMA-LAD) are
other options that have been successfully
used for single-vessel LAD
disease. The optimal mode of revascularization
for
patients with isolated single-vessel LAD disease is unclear.
The
purpose of the present study was to examine PTCA versus
STENT
versus LIMA-LAD with respect to short- and intermediate-term
outcomes.
Methods and ResultsThis was an observational retrospective
cohort study comparing in-hospital and intermediate-term outcomes and
functional class among patients with isolated single-vessel LAD disease
revascularization. Consecutive eligible patients
were grouped according to their initial
revascularization procedure and systematically
followed up. A total of 704 patients qualified for the study: 469 in
the PTCA group, 137 in the STENT group, and 98 in the LIMA-LAD group.
Follow-up data were complete for 97% of patients and averaged 27±13
months. In-hospital mortality for the PTCA, STENT, and LIMA-LAD groups
was 1.1%, 0%, and 0% (P=0.51), respectively. Median
hospital stays after the procedure for the respective treatment groups
were 1, 1, and 5 days (P<0.001), and occurrences of
in-hospital myocardial infarction were 0.9%, 1.5%, and 1.0%
(P=NS). Repeat revascularization
procedures were performed in 30%, 24%, and 5% of the PTCA, STENT,
and LIMA-LAD groups (P=<0.001 for LIMA-LAD versus other
groups, P=0.11 for PTCA versus STENT). Actuarial 2-year
mortality was 3.9%, 2.6%, and 1% in the PTCA, STENT, and LIMA-LAD
groups (P=0.33).
ConclusionsRevascularization for isolated
LAD disease using PTCA, STENT, or LIMA-LAD results in low in-hospital
adverse event rates and good long-term results. Repeat procedures are
required less often after LIMA-LAD than after either PTCA or STENT.
Long-term mortality was not statistically different, but the trend was
for the lowest mortality with LIMA-LAD, a somewhat higher mortality
with STENT, and the highest mortality with PTCA.
Key Words: angioplasty stents grafting coronary disease bypass revascularization
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Introduction
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The left anterior descending coronary artery
(LAD) is almost
always the largest of the 3 epicardial coronary
arteries. The
LAD typically subtends

50% of the left
ventricular myocardial
mass, or approximately twice as much
as either the right or
the left circumflex coronary
arteries.
1 2 Patients with significant
LAD disease,
particularly when the proximal vessel is involved,
have been noted to
have an adverse cardiac prognosis compared
with patients with
coronary artery disease that does not involve
the
LAD.
3 4 5 Although PTCA, coronary stenting (STENT),
and
left internal mammary artery bypass grafting (LIMA-LAD) are
all
used frequently for this high-risk lesion, the optimal approach
remains
unclear. No prior study has compared the outcomes of
patients with
isolated LAD disease treated with PTCA versus
STENT versus LIMA-LAD
surgery.
The purpose of the present study was to compare short- and
intermediate-term outcomes of patients with isolated LAD disease who
received PTCA versus STENT versus LIMA-LAD surgery.
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Methods
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Overview
This was an observational retrospective cohort study comparing
in-hospital
and intermediate-term morbidity and mortality rates as well
as
functional status among patients with isolated single-vessel
LAD
revascularization who received PTCA or STENT
or LIMA-LAD.
Identification of Eligible Patients
Patients were retrospectively identified for inclusion in the
study from the PTCA and coronary artery bypass surgery
databases at the Mid America Heart Institute, Kansas City, Mo. Patients
were eligible for inclusion if they underwent their procedure between
the dates of July 1, 1993, and October 31, 1997. Patients with
angiographically documented, isolated single-vessel LAD
revascularization with a
70% luminal diameter
stenosis (usually estimated by
1 of a core group of 5
experienced invasive cardiologists) in the proximal or midvessel
location were candidates for the study. The decision as to which, if
any, revascularization procedure to use for each
specific patient was made by the clinical physicians managing the case,
often in consultation between cardiologists and surgical colleagues and
the patient. Systematic guidelines about when to use the different
modalities for revascularization of the LAD were
not used. Only patients who received LIMA-LAD were included in the
surgical group. Any patient with prior coronary stenting or any
type of prior cardiac surgery was excluded as well as any patient
presenting with an evolving acute myocardial infarction. All
patients who underwent any concomitant surgery, such as valve
replacement or repair, or carotid surgery were excluded from the
surgical group.
If the patient underwent a subsequent procedure after the initial index
revascularization procedure, the results were
analyzed by the "intention to treat" principle. For
example, patients who initially underwent PTCA of the LAD but required
stenting of the vessel at a separate procedure remote from the initial
coronary angioplasty procedure were analyzed as PTCA
patients.
By use of these parameters, a total of 704 consecutive
patients with isolated proximal or mid-LAD disease who underwent a
revascularization procedure were identified. This
group included 469 PTCA patients, 137 STENT patients, and 98 LIMA-LAD
patients.
Baseline Data
The patient groups were very similar with respect to baseline
demographic and anatomic variables. Details are outlined in Table 1
. The mean ages were similar (62±13,
60±12, and 61±11 years) as were the mean ejection fractions (49±10,
52±10, and 52±10) in the PTCA, STENT and LIMA-LAD groups,
respectively. The incidence of unstable angina at baseline was
significantly higher in the LIMA-LAD group. Patients in the PTCA group
underwent coronary angioplasty alone or in conjunction with
directional atherectomy in 5.6% of cases and rotational atherectomy in
16%. In patients who received stent implantation, 5.8% of patients
had rotational atherectomy and 1.5% had directional atherectomy.
Values were P=0.003 (rotational atherectomy) and
P=0.05 (directional atherectomy) when the STENT and PTCA
patients were compared. All patients in the STENT group underwent PTCA
with stenting. Patients who received an intracoronary stent
were discharged on ticlopidine and aspirin. High-pressure balloon
inflation was used, and stent underexpansion was avoided; in some
cases, intravascular ultrasound was used as a guide. Angiography
revealed coronary obstructions in non-LAD vessels in a small
number of the PTCA, STENT, and CABG groups (
70% stenosis in
the right coronary artery: 1.2%, 1.4%, and 5.6%,
respectively; in the circumflex artery: 2.5%, 1.4%, and 14.0%,
respectively). Note that CABG patients had a higher incidence of
totally obstructed non-LAD vessels in the right coronary and
left circumflex arteries (PTCA patients: 0.3% and 0.7%, respectively;
STENT patients: 5.6% and 0.8%, respectively; and CABG patients: 0.7%
and 2.8%, respectively). Previous PTCA had been performed in 33.5%,
34.3%, and 41.8% (P=0.29) of PTCA, STENT, and CABG
patients, respectively. Previous LAD PTCA had been performed in 22%,
25.5%, and 28.6% of the PTCA, STENT, and CABG patients, respectively
(P=0.34). Proximal LAD disease was present more often in
the LIMA-LAD group than the other 2 groups (Table 1
). Other
major baseline characteristics of the 3 groups were similar; these
characteristics included the sex of the patient, baseline
creatinine, and diabetes.
Follow-Up
Follow-up was complete in 97% of patients and was performed
between November 1997 and February 1998. A comprehensive follow-up
survey used both mail and telephone questionnaires. In addition to the
follow-up survey, subsequent hospital and outpatient records were
reviewed on all patients who reported any major events.
Statistical Analysis
Kaplan-Meier survival analyses were performed to
evaluate differences in intermediate outcome among the 3 groups.
Event-free survival was defined as freedom from death, myocardial
infarction, and repeat revascularization
procedures. Procedural myocardial infarction was defined as the
presence of new Q waves that were 0.03 seconds in width and/or one
third of the QRS complex in
2 contiguous leads. A multivariable
analysis was carried out evaluating independent predictors of
subsequent revascularization procedures. Repeat
revascularization was modeled by using the Cox
proportional hazards regression model. The treatment group (PTCA versus
STENT versus LIMA-LAD) was forced into the model, and stepwise
variable selection was used to identify further significant
factors. Categorical variables were compared using Students
t test and
2 methods.
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Results
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In-hospital events were rare among all 3 groups (Table 2

). In-hospital
death occurred in 5
(1.1%) of the 469 PTCA patients; no patient
died in hospital in the
STENT or LIMA-LAD group (
P=NS). The
median length of stay
after the procedure was only 1 day for
both the PTCA and STENT groups;
this was significantly shorter
than the median stay of 5 days in the
LIMA-LAD group (
P<0.001).
In-hospital transient
ischemic attack without permanent neurological
sequelae
occurred in 2 patients in the LIMA-LAD group; no patient
suffered a
postprocedural neurological complication in the PTCA
or STENT group
(
P=NS).
Intermediate-term follow-up was obtained in 97% of patients, with a
mean follow-up of 27±13 months. The frequency of repeat
revascularization procedures was significantly
higher in both the PTCA and STENT groups compared with the LIMA-LAD
group (Figure 1
). The need for a
subsequent revascularization procedure in the STENT
group (24%) was marginally lower than in the PTCA group (30%,
P=0.11). Frequency of myocardial infarction was low in all
groups, without any meaningful differences between them. The 2-year
actuarial mortality trended lowest (1.1%) in the LIMA-LAD group
compared with 2.6% in the STENT group and 3.9% in the PTCA group,
although the differences did not meet statistical significance
(P=0.33) (Figure 2
). The
survival advantage of LIMA-LAD over PTCA was exaggerated in patients
who had proximal LAD rather than mid-LAD disease. Patients with
proximal LAD disease that underwent PTCA had a 2-year mortality of
5%.

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Figure 1. Incidence of repeat
revascularization procedures (PTCA or CABG) during
follow-up. Compared with the LIMA-LAD (LIMA) group, both the STENT
group (P<0.001) and the PTCA (balloon) group
(P<0.001) experienced higher rates of
revascularization procedures. The STENT group fared
marginally better than did the PTCA group
(P=0.11).
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Figure 2. Twenty-four month all-cause mortality. Although
death rate during follow-up trended lowest in the LIMA-LAD group
compared with the STENT and PTCA groups, differences did not meet
statistical significance (P=0.33).
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By use of multivariable analysis modeling, the only
resulting significant baseline factors predicting need for subsequent
procedures were PTCA (odds ratio, 4.7 versus LIMA-LAD), STENT (odds
ratio, 3.3 versus LIMA-LAD), and diabetes (odds ratio, 1.45 versus
nondiabetics) (Table 3
).
Total event-free survival, calculated using actuarial (Kaplan-Meier)
methodology, was substantially better in the LIMA-LAD group than in the
PTCA or STENT group (Figure 3
).

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Figure 3. Freedom from any cardiovascular
event (death, myocardial infarction, or repeat
revascularization procedures) during follow-up. The
LIMA-LAD group experienced the best event-free survival, and the PTCA
group experienced the worst, with the STENT group intermediate between
the two (P<0.001 for the 3 curves).
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Discussion
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The present study showed that
revascularization for isolated
LAD disease using
PTCA, STENT, or LIMA-LAD resulted in low in-hospital
morbidity and
mortality rates and good intermediate-term results.
Repeat
revascularization was required significantly more
often
after both PTCA and STENT than after LIMA-LAD, and event-free
survival
was superior in the LIMA-LAD group. Intermediate-term
mortality
was not significantly different, but consistent
trends were
noted, with the lowest mortality in the LIMA-LAD group, a
slightly
higher mortality rate in the STENT group, and the highest
mortality
after PTCA.
In general, patients with single-vessel coronary artery disease
are treated with medical therapy or PTCA. In a study comparing
angioplasty with medicine,6 69 of the 212 patients with
single-vessel disease who were randomly assigned to PTCA or medical
therapy had a significant stenosis in the proximal LAD. At
follow-up after 6 months, the PTCA patients had superior exercise
tolerance and improved anginal status compared with the medically
treated patients. However, PTCA of the LAD is limited by the frequent
occurrence of restenosis.7 8 Compared with PTCA of
the proximal LAD, STENT has been documented to result in a
significantly decreased risk of restenosis.9 10 11 A
trial involving 120 patients with symptomatic isolated LAD
stenosis randomized patients to STENT or PTCA.9
The restenosis rates at 12 months were 19% for the stented
group versus 40% for the PTCA group (P=0.02). Additionally,
12-month rates of event-free survival were 87% after stenting versus
70% after angioplasty (P=0.04).
CABG surgery using LIMA-LAD has been documented to be an effective
treatment strategy for isolated stenosis of the proximal
LAD.12 Studies have been performed comparing LIMA-LAD with
PTCA of the LAD. One study showed similar long-term survival rates in
these 2 groups, with a greater need for repeat
revascularization procedures in the PTCA group and
a lower incidence of overall cardiac events in the patients who
underwent LIMA-LAD.13 Another study in which patients were
randomly assigned to bypass surgery, PTCA, or medical therapy indicated
that patients who underwent surgery that included LIMA-LAD had a
significantly lower incidence of cardiac events during follow-up than
did patients assigned to PTCA or medical therapy.14 In 2
large database studies, hazard-analysis risk adjustment
revealed that patients with LAD disease, especially in the proximal
segment, had superior intermediate-term outcomes after CABG surgery
than after PTCA.3 4 In single-or double-vessel disease not
involving the LAD, outcomes were similar after bypass surgery or PTCA.
Follow-up studies extending for 17 years indicate that people with
single-vessel LAD disease have long-term survival rates after LIMA-LAD
that are as good or better than the rates in an age-matched population
without coronary disease at baseline.15
The present study shows, as do prior studies,16 that
STENT is superior to PTCA with respect to need for repeat
revascularization procedures. However, in the
present study, 24% of patients still required another procedure
after STENT. On the other hand, repeat procedures after LIMA-LAD were
quite uncommon and occurred significantly less often than after either
PTCA or stenting.
CABG surgery does entail substantially higher early morbidity rates
than do percutaneous approaches. The median
postprocedure length of stay was 5 days after LIMA-LAD versus only 1
day for either PTCA or STENT. The in-hospital mortality rates, however,
were similar in the 3 groups. Although a decreased length of stay has
been shown to carry initial cost and patient comfort advantages, the
need for repeat revascularization procedures during
follow-up at least partially offsets these early benefits of the less
invasive approach.17
Study Limitations
The present study is not a randomized trial; thus, baseline
differences between the groups may have accounted for some of the
observed differences. However, the findings were very
consistent with other recent reports concerning these
procedures. Technique and technology continue to improve rapidly in the
field of coronary revascularization. For
instance, coronary stents continue to evolve with improved
designs and potential for adjunctive therapy, such as
intracoronary radiation, that may reduce rates of
restenosis.18 Minimally invasive CABG surgery
without using cardiopulmonary bypass is being explored as a
less traumatic option for LIMA-LAD.19 These changes when
incorporated into clinical practice may alter the relative outcomes in
patients with isolated LAD disease.
The present study confirms that the patient with isolated LAD
disease has 3 effective revascularization options.
Additional studies will be important in evaluating the effectiveness of
aggressive medical therapy (eg, lipid-lowering drugs, antiplatelet
therapy, and ß-blockers) as either an alternative to or adjunctive
therapy for coronary revascularization in
patients with isolated LAD disease.20
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Footnotes
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Reprint requests to James H. OKeefe, Jr, MD, Mid America
Heart Institute, 4401 Wornall Rd, Kansas City, MO 64111.
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