Role and Limitations of Coronary Angiography, Angioplasty and Coronary Bypass Surgery

Item

Title
Role and Limitations of Coronary Angiography, Angioplasty and Coronary Bypass Surgery
Creator
Anant Phadke
Date
1989
extracted text
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ROLE AND LIMITATIONS OF
CORONARY ANGIOGRAPHY, ANGIOPLASTY & CORONARY BYPASS SURGERY
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Patients or their relatives sometimes ask the opinion
of their family-physicians or other doctors known to them about
the desirability of undergoing invasive and costly cardiac
procedures as per the recommendation of the experts. The
doctor concerned is put in an awkward position.
(S)he can’t
simply say "follow the expert," since unfortunately there
are reasons to believe that the expert recommendations in
this field in India are sometimes given for reasons other than
those guided by scientific evaluation and the interests of the '>
patients, On the other hand an average doctor is simply not
equipped to advise the patient in this new, complex, specia­
lized field. This brief note is meant only to help doctors
to acquire a Critical scientific perspective about theseprocedures. If any advice is grossly different from this pers­
pective, the doctor would better ask for clarification from
the concerned expert or advise the patient to seek a second
expert opinion; without drawing any hasty conclusions on his/
her own.

This note has been prepared for discussion, with the
help of standard, critical scientific literature • the indi­
cations given in the appendix are primarily based on
" The Heart " by Willis Hurst, 7th editionl 1990,

INDICATIONS

FOR

CORONARY

ANGIOGRAPHY

Although clinical examination and various noninvasive methods
described are invaluable, the definitive diagnosis of coronary
artery disease and a precise assessment of its anatomical
severity and its effects on cardiac performance and metabolism
is sometimes needed. This requires cardiac catheterization,
coronary angiography and left ventriculography.

Several questions need to be resolved
(a) In which patients should it be performed ?
(b) How will this test aid in the further management
of the patient ?

(c) What are the risks involved ?

(d) Are any special precautions necessary 1

Although no unanimity exists, in most instances
coronary angiography is helpful in patients with chronic
stable angina as well as those with unstable angina. For
patients with chronic stable angina, an angiographic study is
performed as a next step after a treadmill test, if this were
to show a strongly positive response for exercise inducible
myocardial ischaemia; provided of course that the patient is
ready for the logical sequelae of a coronary angiogram, viz.
revascularization procedures, if these were" to be required.
If this were not to be the case, there seems little indication
for undertaking the trouble and risk of an invasive procedure
like CAG ICoronary Angio Gram I.
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In those patients.of unstable angina where medical
therapy fails, angiography Should be carried out immediately,
i.e., as soon as the haemodynamic condition has stabilized,
unless there are obvious contraindications to revascularization
procedures. On the other hand in patients who respond to
medical therapy, it is safer to perform the invasive tests
several days after the symptoms have stabilized. These proce­
dures are helpful in that they identify several subgroups of
patients with unstable angina and can thus be used to guide
therapy :
1) Patients with Left Main Coronary Artery Disease
(LcAD) the mdst life threatening form of the disease, where
urgent surgery is essential.
2) Patients with multivessel CAD without a clear
culprit lesion, who are not suitable for PTCA (Percutaneous
Transluminal Coronary Angioplasty)--these patients should
undergo ACBG (Aorto Coronary Bypass Graft) surgery on a semiurgent basis- i.e. within 8 to 10 days after the patient's
condition is stabilised.

3) In a small group (5-10% of all patients with unstable
angina) with no demonstrable significant stenotic lesion, pro­
gnosis appears to be excellent and coronary spasm-is the most
likely cause—intensification of medication by stepping up the
dose of nitrates and/or calcium antagonists is indicated.
4) Patients with single/double vessel disease with
discrete proximal lesions that are amenable to PTCA,

5) Patients with diffuse distal disease that are unsuitable for both PTCA and ACBGS,
Which are the patients who are unsuitable for angio­
graphic examination ? Patients who are suffering from another
serious life threatening illness with a poor prognosis; those
with refractory ventricular tachyarrhythmias at rest; those with
profound hypotension.
COMPLICATIONS OF CORONARY ANGIOGRAPHY

It must be clearly understood that the incidence of
complications is brought down significantly by the availability
of and introduction of better equipment and material used in the
performance of an angiographic examination. It is .also reduced
by increasing experience and skill of the operator. Also, the
complication rate is significantly reduced by the transfemoral
technique.

In large angiographic series, mortality ranges around
0,25%. Nonfatal myocardial infarction occurs in around 0.2 %.
Potentially serious arrhythmias (VT, VF or transient asystole in
0.80%, local arterial ccmplications in 0.85% and cerebral isch­
aemic events occurred in 6.1%. Mortality as well as other non­
fatal complication rate is higher in thos© with impared LV
function.

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INDICATIONS FOR CORONARY ANGIOPLASTY;

The classical indications of a proximal, discrete,
solitary, concentric, significant, subtotal, noncalcific
lesion have rapidly given way to, with increased experience
and application of the procedure to far more widespread
patient and lesion population/profilfe.

One would today expect to have angioplasty offered
as a legitimate therapeutic modality in even multivessel
disease. The scope for application of the procedure is far
greater today than was initially though likely by Gruentzig.
One should however remember a few riders before
jumping onto the angioplasty bandwagon.
1) PTCA is associated with a "learning curve" for
the operator and this may last for upto the first 150 cases.

2) pTCA should be practised only by operators with a
yearly procedure rate of at least 100 cases, to make the
learning curve applicable for the individual operator.
( AJC-PTCA Registry 1985).

3) PTCA should be practised only at centres with a
yearly procedure rate in excess of 250 cases and with standby
facilities of emergency AG8GS available at all times that
PTCA is being attempted. ( ibid.)
4) PTCA as an alternative method to CABGS by way of
much reduced costs is not the correct case in our country,
where a CABGS can be performed from as low as Rs. 35,000/in a private hospital, and the least cost for PTCA works
out to about Rs, 37,000/-, chiefly due to the cost of the
disposables put to use, all of which are by necessity
imported.
Another factor which must be remembered is that as
many as 33-35% of all primarily successful PTCA's develop
symptomatic reocclusion in the first six months following
the primary’ prccedure-and the rate of restenosis .without
symptoms is really not well known from any large series.
Some of these patients are .amenable to a re-PTCA, others
will need formal coronary bypass surgery.

The last and perhaps the most important aspect of
PTCA is that of failed and complicated angioplasty. The
latter consists of the following possible complications s
(a) Coronary dissection
(b) Coronary artery perforation/rupture
(c) Acute closure (precipitation of a
myocardial infarction)
(d) Coronary embolisation
(e) Severe angina
(f) Cardiogenic shock/Left Ventricular
dy sfunction/lifethreatening arrhythmia
(g) Death.

The accepted complication rate is 5-10% especially in the
hands of a beginner and gradually reduces with increasing
experience and expertise.
(....

Many of the complications are treated with an emergency
coronary bypass surgery (which has, in the best of centres, a
four-fold or greater risk as a routine, elective surgery).
Most centres in our country are not geared for the possibility
of an emergency bypass surgery especially at the hands of a
reliable cardiac surgeon.
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The problem of a failed angioplasty is even more vexed
and depressing as most centres/physicians refuse to accept this
limitation of the person and/or procedure and instead do not
offer the patient what he ought to.be: the alternative revascul­
arization procedure of iSCBGS. Surely what is an acceptable
failure is transformed into a facesaving device, and the patient
is offered surgery after an interval, so that all appears
hunky-dory.
CORONARY BYPaSS SURGERY:
Coronary revascularization surgery really got a defi­
nitive and scientific liftoff with the introduction • /
of
coronary: bypass surgery in 1969 by Favaloro. The procedure
rapidly made_ great strides and today occupies a frontline
position in the therapeutic armamentarium against a curse of
modern day life-atherosclerotic coronary artery disease.

Unfortunately, as happens with many other useful modes
of therapy, ACBGS has also been clouded and shrouded by a cloak
of aura, glamour and hype so much so that the last has overtaken
the rational indications and we discover to our dismay that ACBGS
is advised far too often, and even in truly unindicated situations.
In order to clear away some of the misconceptions, -let us
take fresh look at the issue

ACBGS is basically said to(a) improve the quality of
life and (b) improve the longevity of life. Let us look at each
and decide fdr ourselves what is the position of ACBGS today.
r

The results of large multicentric cooperative studies
with a 10 year follow-up (CASS study, Veterans Administration
Study, and the European multicentric study on ACBGS " European
CASS" ) have all shown that real prolongation of life occurs
only in a few selected subgroups :

1) Left main coronary artery disease,
2) Triple vessel disease with LV Dysfunction,
3) Proximal LAD disease.
In all other subsets, ACBGS does not really prolong life 1
What then of the improvement of the quality of life ?
While a successful ACBGS undoubtedly does ameliorate symptoms
like angina, and also does improve effort tolerance, these can
also be achieved with a fair degree of success in most cases
with the drugs available today. Except for the rare case of
unstable angina refractory to medical (max.) therapy, ACBGS
may not truly be the sole means of improvement bf the quality
of life.
■
.
Does this mean that ACBGS should not be performed at all?
No. Certainly not. But it does indicate the presence of a well
defined subset of patients which will benefit by surgery as also
a fairly large patient population which may not do so, and tells
us of the need to be extremely discriminating in our choice of
patients for surgery.
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.5.
Appendix

INDICATIONS FOR CORONARY ARTERIOGRAPHY

1) Chronic stable. angina
2) Unstable ’“angina
.3) "Left Ventricular Failure Secondary to
Coronary Artery Disease
4) Recurrence of chest-pain after bypass surgery
where Stress-test is not contributory or is
contraindicated.
5) Chest-pain of uncertain>suspected cardiac
aetiology where stress-test is not contri­
butory or is contraindicated.
6) Valvular heart disease in patients over forty
years of age as a preoperative evaluation if
clinical picture or ECG is suggestiveischaemic Heart Disease
7) "Sudden death" ventricular fibrillation
survivors if IHD is suspected due to
symp tom s/ECG/Stress-test.
Coronary arteriography is NOT indicated in :-

1) Asymptomatic post infarction patient.
2) Mildly positive exercise test, no angina
3) Family history of premature coronary disease.

INDICATIONS FOR CORONARY ANGIOPLASTY;

.

I) Single Vessel Coronary Artery Disease Asymptomatic or
mildly symptomatic significant lesion in a major
epicardial coronary artery that subtends a large
area of viable myocardium and who ; (i) show obj­
ective evidence of severe myocardial ischaemia
(ECG/stress test); (ii) have been resuscitated
from cardiac arrest cr sustained ventricular
tachycardia in the absence of acute myocardial
infarction :
Asymptomatic cr mildly symptomatic patients who should NOT
undergo angioplasty : (i) have only a small area of myocardium
at risk or (ii) do not manifest evidence of ischaemia
during laboratory testing, or (iii) have borderline
lesions less than 50%° in diameter; or (iv) have
lesions which predict poor chance of success or
a high risk of abrupt closure, or (v) have disease
which places the patient in a high-risk group for
mortality and morbidity.
II) Single vessel coronary artery disease symptomatics? Patients
with angina pectoris, class II,III,IV & unstable
angina pectoris with single vessel disease Whoi) have significant lesions in a major epicardial
coronary artery subtending atleast a moderatesized
area of myocardium, and who show evidence of myocar­
dium, and who shew evidence of myocardial ischemia
during lab-testing; or (ii) have angina pectoris that
has been inadequately responsive to medical Rx. ile^.
■ angina interfering with the-pafciontfs usual activities
(iii) have intoleranceifo medical therapy because of
side-effects.

( Ctd....

.6.

Ill) MULTIVESSEL DISEASE :
Asymptomatic or mildly symptomatic
patients who
awa
have a significant lesion in a major epicardial
coronary artery that could be dilated and in
which nearly complete revascularization could
be accomplished because the additional leison(s)

subtend a small viable or nonviable area of
myocardium or where all significant stenotic

lesions wi’ll be dilated.
IV) MULTIVESSEL SYMPTOMATIC
Significant lesions in each of two major epicardial

coronary arteries both subtending at least moderately

sized areas of viable myocardium.
V) Acute myocardial infarction:Recurrent episodes of chest-pain
not responding to medical therapy particularly with
ischaemic ECG changes and significant CAD demonst­
rated by angiography.

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