THERAPY AND PREVENTION
PTCA
Should coronary arteries with less than 60%
diameter stenosis be treated by angioplasty?
THOMAS ISCHINGER, M.D., ANDREAS R. GRUENTZIG, M.D., JAY HOLLMAN, M.D.,
SPENCER KING III, M.D., JOHN DOUGLAS, M.D., BERNHARD MEIER, M.D.,
JAMES BRADFORD, PH.D., AND ROSE TANKERSLEY, R.N., B.S.N.
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ABSTRACT We evaluated all patients receiving percutaneous transluminal coronary angioplasty
(PTCA) in the past year for mild stenosis (60% or less diameter narrowing, n = 64, group 1) and
compared them with a random sample of 330 patients with greater than 60% stenosis (n = 66, group 2)
treated during the same year. The degree of coronary stenosis before PTCA was 52 + 7% (mean +
SD) in group 1 and 79 + 11% in group 2. The primary success rate was 90% (58 of 64 patients) in
group 1 vs 86% (57 of 66 patients) in group 2. The incidence of complications requiring coronary
surgery after PTCA failed was similar in both groups (3 of 64 in group 1, 4 of 66 in group 2), but there
were four occurrences of myocardial infarction in group 1 and none in group 2 (p < .05). Recurrence of
stenosis was judged on the basis of objective data, 76% of which were angiographic data, in 97% of the
patients with primary success. At a mean interval of 5 months with a mean follow-up period of 7
months, 17 of 58 patients (29%) with primary success in group 1 and 24 of 57 patients (42%) in group 2
developed restenosis. In group 1, restenosis was markedly more severe (73 ±+ 15%) than initial stenosis
(p < .005), which was not the case in group 2. In conclusion, PTCA in mild stenosis has favorable
primary and long-term results, yet carries the risk of myocardial infarction and emergency operation
and may, in some cases, even accelerate the disease process.
Circulation 68, No. 1, 148-154, 1983.
INTRODUCED into the treatment of coronary artery
disease in 1977' as an alternative to coronary artery
bypass grafting (CABG) primarily in single-vessel disease, percutaneous transluminal coronary angioplasty
(PTCA) has proved to be an effective and safe procedure.2 In 5 years of application, indication for PTCA
has expanded to bypass grafts, multivessel disease,
and lesions that are technically more difficult to
treat.4'
However, the rapidly increasing use of PTCA and
its growing popularity may cause a trend toward its
preventive application for mild stenoses at an earlier
stage of coronary artery disease. To examine whether
this is justified, we retrospectively evaluated early and
late outcome of PTCA in a series of consecutive patients with 60% or less diameter stenosis in comparison
with a random sample of patients with tight stenosis.
From the Division of Cardiology, Department of Medicine, Emory
University School of Medicine, Atlanta.
Presented in part at the annual meeting of the American Heart Associ-
ation, November 1982, Dallas.
Address for correspondence: Andreas R. Gruentzig, M.D., Division
of Cardiology, Department of Medicine, Emory University School of
Medicine, 1364 Clifton Rd., Atlanta, GA 30322.
Received Dec. 31, 1982; revision accepted March 24, 1983.
148
Methods
Patients. All patients receiving their first PTCA for a luminal
diameter stenosis of 60% or less in a native vessel from December 1980, through December 1981, (n = 64, group 1) were
evaluated and compared with a one out of five random sample of
330 patients undergoing their first PTCA for a greater than 60%
luminal diameter stenosis within the same time (n = 66, group
2). The random sample was drawn to have similar group sizes
and to facilitate acquisition of complete objective follow-up
data.
A 60% degree of luminal diameter narrowing corresponds to
a cross-sectional stenosis of 84% and may represent a borderline
hemodynamically significant lesion.6' 7, 8 All patients presented
with angina pectoris that, according to the referring physician,
was poorly controlled by previous drug treatment. The indication for PTCA in these patients was based on the angiographic
finding of an accessible coronary lesion, on the candidacy of
these patients for coronary surgery as a result of their clinical
status, and on the clinical data provided by the referring physician. The results of exercise testing (treadmill exercise according to the Bruce protocol) or nuclear studies (thallium scintigraphy or technetium first-pass study) in patients at rest and
during exercise, although routinely performed before and after
PTCA, did not influence the indication established by the criteria mentioned above.
PTCA. PTCA was performed according to the technique
described elsewhere.1 To assess the result of coronary angioplasty, selective coronary angiography was performed immediately before and after PTCA. The luminal diameter stenosis was
calculated as the mean of three oblique projections with a computerized caliper (A2D Cinemetric Viewer and Prodical 1101
CIRCULATION
THERAPY AND PREVENTION-PTCA
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Programmable Digital Caliper). This method has been shown to
be more reliable in judging the degree of coronary stenosis than
those in which only one projection is used9 and concurs with
recommendations derived from pathohistologic studies. 10 According to the National Heart, Lung, and Blood Institute
(NHLBI) criteria, a reduction of at least 20% of the initial
degree of stenosis was considered a successful dilatation if no
coronary surgery (CABG) was required during hospitalization.
In all cases, pressure was routinely monitored and pressure
gradients across the stenosis were recorded, with the guide
catheter representing aortic pressure and the main lumen of the
dilatation catheter transmitting distal coronary pressure. Pressure gradients were calculated from the mean proximal and
distal pressures by a computerized program (Meddars 300,
Honeywell).
Drug treatment. Oral nitroglycerin and nifedipine therapy
was started in all patients before the procedure and was continued for 2 months thereafter. During dilatation, heparin and lowmolecular weight dextran were routinely administered and intracoronary nitroglycerin was given to prevent coronary spasm.
Patients in both groups received warfarin (Coumadin, 2 x
partial thromboplastin time) or aspirin in low doses (325 mg) in
the follow-up period of 6 months after PTCA as part of an
ongoing randomized study.1' This did not influence our results
because 20 patients in each group were on warfarin (31% vs
30%).
Follow-up. All patients were asked to take a treadmill exercise test, whether or not they also underwent nuclear study,
during follow-up and to have a control coronary angiogram at 6
months after PTCA if they were symptom-free. If symptoms
recurred, they were advised to have a repeat angiogram as soon
as possible. Outside restudy films were usually sent to us and
assessed by us in the fashion mentioned above. Questionnaires
and phone calls to the patients or their referring physicians were
used to complete our follow-up information.
The follow-up period ranged from 1 to 16 months (mean 7. 1)
in group 1 and from 3 to 15 months (mean 7.4) in group 2.
Objective follow-up data were obtained in all but two patients in
each group; in 76% of group 1 patients (43 of 58) and 83% of
group 2 patients (47 of 57) angiographic data were available.
Restenosis (recurrence), judged angiographically as a mean of
three projections, was defined as a more than 50% loss of gain in
luminal diameter achieved with the previous PTCA. For example, a 90% stenosis is reduced to 10%, which is a gain of 80% in
luminal diameter. A 50% loss of this diameter improvement is
40% and therefore a stenosis of more than 50% (10% + 40%) at
restudy would be considered a recurrence. Besides angiographic data, follow-up data consisted of exercise test results in
patients who underwent nuclear study and those who did not. A
positive exercise treadmill test result during follow-up after a
negative result after PTCA was considered indicative of recurrent stenosis of the dilated vessel if no angiogram was available.
This was the case in one patient in group 1 and in three patients
in group 2. An exercise treadmill test result that continued to be
negative after PTCA was considered to be indicative of continued success if no angiogram was available. This was the case in
eight patients in group 1 (one exercise treadmill test result was
considered equivocal) and four patients in group 2. Subjective
follow-up data were obtained in only two patients in each group.
PTCA in these patients was considered a continued success
because the patients have reported continued improvement of
symptoms.
Statistics. Data collection and random sampling were aided
by a computerized cardiac data bank. Student's t test and the
chi-square test were used to evaluate statistical significance. A p
value greater than .05 was considered nonsignificant and results
were expressed as mean + SD.
Vol. 68, No. 1, July 1983
Results
Primary success. Group characteristics are described
in table 1. The patient characteristics of the random
sample (group 2) match well those of the consecutive
patients of group 1 with the exception that there was a
prevalence of left anterior descending coronary artery
(LAD) lesions in patients referred to us for PTCA of a
mild stenosis. This may reflect the common opinion
that because of the myocardium at risk, a mild lesion in
the LAD is more readily considered an indication for
PTCA.
Primary success was similar in both groups, 90%
(58 of 64 patients) in group 1 vs 86% (57 of 66 patients) in group 2. Successful initial angioplasty reduced coronary stenosis from 52 + 7% to 23 + 11%
in group 1 and from 79 + 1 1% to 31 ± 13% in group
2. The mean pressure gradient across the lesion correlated well with the degree of stenosis before and after
PTCA (table 2).
Failures occurred in six patients of group 1, three of
which (two right coronary artery [RCA], one LAD)
were due to the inability to reach or cross the lesion
(one patient needed CABG 2 days after PTCA), one
could not be dilated (LAD) and two had an acute closure of the artery (LAD) with subsequent CABG and
myocardial infarction. Two patients (LAD) in whom
PTCA was considered a primary success, had a side
branch closure with evidence of myocardial infarction.
In group 2 there were nine failures, seven of which
were due to the inability to reach or cross the lesion
(two patients needed CABG the next day), and two
were due to dissection of the artery (RCA and LAD)
with subsequent CABG. Comparing group 1 with
group 2, there were four occurrences of myocardial
infarction in group 1 and none in group 2 (p < .05,
table 3); three patients needed CABG in group 1 and
four patients in group 2 needed CABG. None of the
TABLE 1
Characteristics of group 1 and group 2
n
Age (years)
Male (%)
SVD (%)
Stenoses
LAD (%)
RCA (%)
LCX(%)
Previous MI (%)
patients
p value
Group 1
Group 2
64
52 (37-70)
70
92
53 (34-71)
80
94
NS
NS
NS
83
16
1
20
67
26
7
20
< .05
66
NS
NS
NS
SVD = single vessel disease; RCA = right coronary artery; MI =
myocardial infarction.
149
ISCHINGER et al.
groups had normal follow-up coronary angiograms or
objective data that indicated patency of the dilated
TABLE 2
Primary results of initial PTCA
n
Primary success
Stenosis (%)
Before PTCA
After PTCA
Pressure gradient (mm Hg)
Before PTCA
After PTCA
Group 1
Group 2
64
58 (90%)
66
57 (86%)
52 + 7
23 -+1-1
79-+ 11
31±+ 13
38+15
15 + 10
52+14
15 -+11
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patients of group 1 who had CABG and/or myocardial
infarction had angiographically demonstrable collaterals to the diseased vessel on the pre-PTCA angiogram,
while two of the four patients of group 2 did show
collateral circulation. Dissections and side branch closures not resulting in myocardial infarction or CABG
were seen in one and six patients, respectively, among
the primary successes of group 1 and group 2.
Follow-up results. As shown in figures 1 and 2, in
72% of all group 1 patients (46 of 64) and in 67% of all
group 2 patients (44 of 66) in whom PTCA was attempted, the operation was a long-term success (=
total success) as determined after repeat dilations. In
detail, at a mean interval of 4.8 months (range 2 to 10)
17 of 58 patients (29%) with primary success in group
1 and 24 of 57 patients (42%) in group 2, at a mean
interval of 4.5 months, were judged by objective data
to have recurrent stenosis at the previously dilated site
of the coronary artery (figures 1 and 2). The recurrence
rate of LAD stenoses was 33% (16 of 49, group 1) and
46% (17 of 37, group 2) as compared with the recurrence rate of 13% (1 of 8, group 1) and 31% (6 of 16,
group 2) of RCA stenoses and the even lower recurrence of left circumflex stenoses (0 of 1 vs 1 of 4). One
patient in each group was found to have recurrence of
chest pain due to a new coronary stenosis in a different
vessel. In group 1, 11 of 17 patients with restenosis
underwent repeat angioplasty. The remaining six patients with recurrent stenosis were controlled by medical treatment. Five patients in group 1 reported persistence of previous symptoms and had a normal coronary
angiogram. On two patients in group 1 and one patient
in group 2 no follow-up information was available.
Two patients died during follow-up in group 1, one
due to renal failure and one due to aortic dissection
with medial cystic necrosis in the presence of aortic
insufficiency. In group 2, 14 of 24 patients with restenosis had repeat PTCA and seven patients underwent elective CABG; three patients continued medical
treatment. All but two of the other patients of both
150
vessel.
In group 1 patients who underwent angiographic
restudy, restenosis was markedly more severe (73 +
15%) than the degree of stenosis before initial PTCA
(52 ± 7%, p < .005; figure 3). A typical example is
given by figure 4, which shows the left anterior
oblique (LAO) projections of the coronary angiogram
of H. B., a 51-year-old male patient who had a 4 month
history of angina pectoris before PTCA. In figure 4, A,
the proximal LAD stenosis before PTCA was judged to
be a 47% diameter narrowing in LAO 60° projection,
54% narrowing in right anterior oblique (RAO) 300
projection, and 42% narrowing in lateral projection,
which led to a mean of 48% diameter stenosis. Accordingly, stenosis after PTCA was judged to be 27% (figure 4, B). Recurrent angina after 3 months led to restudy, which revealed a 77% restenosis (figure 4, C).
Repeat PTCA reduced stenosis to 30% (figure 4, D).
In group 2, by contrast, the degree of recurrent stenosis (82 + 12%) was similar to the degree of the
initial stenosis (83 + 11%, NS; figure 3).
Repeat PTCA. Repeat PTCA was performed in 11 of
17 patients with recurrent stenosis in group 1 and in 14
of 24 patients with recurrent stenosis in group 2. Repeat PTCA was successfully performed in all patients
of both groups except in one patient of group 1, who
required emergency CABG. No difference between
the groups was noted in degree of stenosis and pressure
gradients after repeat dilatation. Two patients in each
group underwent elective CABG 2 to 4 months after
repeat PTCA. More than 2 of 3 (67%) of the patients of
both groups who had received repeat PTCA are symptom-free at a mean follow-up interval of 7 months
(range 2 to 13), which exceeds the 4.6 month time
frame in which the restenoses occurred in our series.
Discussion
Refined catheter technology and the growing skill of
operators have allowed a primary success rate of 90%12
to be achieved in appropriately selected patients.
These results justify enthusiasm and a more aggressive
patient selection in terms of coronay anatomy, but do
TABLE 3
Complications of PITCA
Group 1
Group 2
p value
4
3
0
4
< .05
NS
MI
CABG
MI
=
myocardial infarction.
CIRCULATION
THERAPY AND PREVENTION-PTCA
FIGURE 1. Follow-up results of patients with 60%
1). Med Tx = medical treatment; EM CABG = emergency coronary
bypass surgery; el. CABG = elective coronary bypass surgery; t = death.
or less diameter stenosis (group
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not necessarily imply an expansion of clinical indication," S which originally was based on the patient's
need for coronary surgery. In all previous studies on
effectiveness and safety of PTCA, dilatation was performed in patients with an average degree of stenosis
of more than 70% luminal diameter narrowing."2'3'5
No data has been available supporting the use of PTCA
in'patients with milder coronary stenosis with less than
60%' luminal diameter narrowing. The value of coronary angioplasty in this subset of patients should be
determined by its primary success rate, its complications, and long-term results.
As one would expect, primary success rate is higher
in patients with mild stenosis, but the difference of
90% in the mild stenosis group vs 86% in the con'trol
group is not statistically significant.
Complications requiring bypass surgery, however,
were equally frequent in both groups. The incidence of
myocardial infarction is even higher in patients with
mild stenosis, which might be explained by the lack of
sufficient collateral blood flow' in case of complication, although angiographically demonstrable collaterals have not been shown to guard necessarily against
myocardial infarction after failure of PTCA. '
GROUPIE
stenosis
24
nd PTCA
14
J
Vol. 68, No. 1, July 1983
FIGURE 2. Follow-up results of patients with greater than 60% diameter stenosis (group 2). Abbreviations are as in figure 1.
151
ISCHINGER et al.
ANGIOGRAPHIC RESULTS
GROUPI
N
=
GROUP II N
43
=
47
cn
cn
co
ao-
Pre PTCA
Post PTCA
Restudy
Pre PTCA
Post PTCA
Restudy
FIGURE 3. Degrees of stenosis in successfully dilated patients of groups 1 and 2 before and immediately after PTCA and at time
of angiographic restudy. In group 1 restenosis is markedly more severe than initial stenosis.
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Recurrence rate is lower in mild stenosis, but the
difference was not significant (29% vs 42%) due to
small group sizes. The prevalence of LAD stenoses in
group 1 enhances this difference since LAD lesions
have the highest recurrence rates. The total number of
long-term successes of all group 1 patients in whom
PTCA was attempted is only slightly higher than the
total number of successes of all group 2 patients in
whom PTCA was attempted.
However, the severity of recurrent stenosis in patients with originally mild stenosis significantly exceeds the initial degree. This is in disagreement with
the finding that progression appears to be directly related to the initial severity of stenosis14 and our own
experience with disease progression of individual lesions. Acceleration of the disease process by mechanical dilatation (intimal damage) might be an explanation.
In a number of patients with mild stenoses, symptoms before PTCA persisted after dilatation, which
suggests that several patients in group 1 were inappropriately selected to receive PTCA. Coronary spasm
superimposed on fixed coronary disease may be the
problem in these patients. Since we once noted a total
coronary occlusion after administration of intravenous
ergonovine, we did not routinely test our patients with
ergonovine before PTCA. However, these patients,
who present with various manifestations of chest pain
not clearly verifiable and or linkable to fixed coronary
disease, represent the challenge and the burden of daily
diagnostic work.
Thus, PTCA in patients with mild stenoses has favorable primary and long-term results, yet carries a
considerable risk of myocardial infarction and CABG
and may in some cases accelerate the disease process
of the dilated coronary lesion.
Clinical implications. The natural course of coronary atherosclerosis is progressive and unpredict152
able. 1"-7 However, progression of coronary disease is
clearly related to time14 17 and may affect more than
40% of patients with angiographically documented
disease within 1 year. 14 Coronary disease is an accelerating process, with increasing severity of arterial involvement, mortality, and progression rate rise.'14 16
In an effort to avoid operating again,18 19 it increasingly has become the practice of coronary surgeons to
bypass not only severe stenoses but also mildly diseased arteries with the anticipation that disease will
progress .20
Since reliable prognosticators of disease progression
have not yet been determined, timely early intervention by PTCA before double- and triple-vessel disease
develops and irreversible myocardial damage occurs
might appear logical and justified, even though symptoms are mild.
Most of the candidates for PTCA have single-vessel
disease and are commonly considered to have a good
prognosis,21 22 particularly if their symptoms are only
mild.23 However, it has been shown recently24 that
more than a third of the survivors of a myocardial
infarction had single-vessel disease. Therefore, patients with single-vessel disease do not represent a
homogeneous patient population. Some patients may
have a poorer prognosis and a more urgent need for an
intervention, especially if the stenosis is located proximally with a large amount of myocardium at risk.
From this point of view PTCA seems to be justified.
However, before PTCA is undertaken the risks of
emergency CABG, myocardial infarction, and rapid
disease progression at the dilatation site, as demonstrated in group 1, should be considered and the patient
should be informed of the risk. The clinical course of
these patients and the angiographic morphology of
their coronary stenoses25 may help identify these patients at high risk and establish a more individual and
valid indication for PTCA in patients with milder steCIRCULATION
THERAPY AND PREVENTION-PTCA
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FIGURE 4. Coronary angiogram in LAO projection of a 51 -year-old male patient (H. B.) who had proximal LAD stenosis
before and after first PTCA (A and B) and before and after second PTCA (C and D).
noses. This also applies to patients who undergo PTCA
for a severe stenosis and have an additional mild lesion
in another vessel, the "preventive" dilatation of which
in the same operating session is tempting. The possible
complications and a recurrence rate of almost 30%
with potential disease acceleration in the dilated lesion
should caution against the application of PTCA in patients with mildly diseased vessels.
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154
CIRCULATION
Should coronary arteries with less than 60% diameter stenosis be treated by angioplasty?
T Ischinger, A R Gruentzig, J Hollman, S King, 3rd, J Douglas, B Meier, J Bradford and R
Tankersley
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Circulation. 1983;68:148-154
doi: 10.1161/01.CIR.68.1.148
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