574
J AM COLL CARDIOL
1983;I(2):574-5
LETTERS TO THE EDITOR
Tetralogy Versus Tetrad and a Wish for
the New Journal
In wishing your new Journal God speed, I would encourage you
to continue to educate and guide us journalistically; at the same
time, do please resist your inclination to tidy up the language. I
noticed with dismay your sanction of the unhappy neologism "Tetrad" on page 1279 of the June 1981 issue of your earlier brainchild and until recently our official journal, The American Journal
of Cardiology. I had hoped this was a one-time editorial aberration
because the previous volume (46) had shown all five Fallot articles
properly titled as "Tetralogy." But no! Volume 48 carried two
Tetrads and Tetralogy was not even indexed-rejected after 93
years of distinguished usage . . . !
You were not, of course, introducing a new word. Tetrad made
a brief, self-conscious appearance in the surgical literature a few
decades previously but was soon dropped by all including its inventors. As an admirer of your journalistic leadership, I would be
slow to regard you as historically insensitive. However. I may
have no option if you have been talked into believing that Fallot
in his use of Tetralogy has been etymologically wrong all the time.
This must be the most fragile of arguments.
Respect for the proper usage of the language is a birthright of
the new journal; you will preserve this by consigning Tetrad into
the outer darkness with Dysrhythmia and other horrible neologisms.
physical activity. Thus, discomfort which is clearly, but only
sometimes, related to exertion is considered to be "cxertional."
Is there prompt relief by rest or nitroglycerin? The word
"prompt" is considered to imply a time span ranging from approximately 30 seconds to 10 minutes. The word "relief" is intended again to imply a general causal relation either to cessation
of physical activity or to administration of sublingual nitrates.
When all three questions are judged by the physician to have
been answered in the affirmative, the discomfort is interpreted as
"typical angina." When only two of the three answers are affirmative, the discomfort is interpreted as "atypical angina." When
fewer than two answers are affirmative, the discomfort is interpreted
as "rionanginal." This classification, although highly subjective,
has several strengths. First, it is practical-being easily learned,
remembered and applied. Second, it is relevant. Thus, by analysis
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Non Anginal
Discomfort
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WALTER SOMERVILLE, MD, FACC
149. Harley Street
London WIN IHG
England
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A Clinically Relevant Classification
of Chest Discomfort
A successful diagnosis of coronary artery disease begins with the
patient history, and therefore with an effective and relevant classification of chest pain. It was recently pointed out, however, that
previously published formats are insufficiently explicit to allow
reproducible clinical application (I). In 1980, we (2) reported our
initial experience with a classification similar to that employed in
the Coronary Artery Surgery Study, which appears well suited to
routine clinical use. This classification is based on three readily
determined historical characteristics which are generally accepted
as being "typical" of ischemic cardiac discomfort:
Is the discomfort substernal? The word "substernal" is intended to be anatomically precise. It therefore excludes the epigastrium, the parasternal area or a transthoracic distribution unless
a substernal component is also present.
Is it precipitated by exertion? The word "precipitated" is intended to imply a general-but not exclusive-causal relation to
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PROBABILITY
Figure 1. Beta frequency distributions of probability for angiographic
coronary artery disease according to symptom classificanon. The x axis is
the probability of disease and the Y axis ISthe frequency of that probability,
expressed in terms of the number of patients withm each symptom group.
For each symptom classification, two distribution curves are Illustrated
The curve labeled H represents the distribution of probability calculated
from the mean and standard deviation (6) for each patient from a computer
program that employs pooled estimates from published data of angiographic
prevalence accordmg to age, sex and symptom class (5). The curve labeled
A IS the distribution of the observed angiographic prevalence, normalized
to the "effective" sample size represented by the mean probability: N =
pq/SD 2 , where p is mean probability, q = 1 - P and SD is the standard
deviation of p. For each symptom class, the dtstributions of probabihty
and angiographic prevalence are similar
0735-1097/831020574-2$03 00
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J AM COLL CARDIOL
1983.1(2) 574-5
LEITERS
575
Table 1. Probability Versus Prevalence of Coronary Artery Disease (CAD)
Patients
Symptom Class
(0+)
(0-)
CAO Probability
(mean ± I SO)
CAO Prevalence
(mean ± I SO)
Nonanginal discomfort
Atypical angina
Typical angina
18
33
46
20
II
4
0.245 ± 0.150
0.673 ± 0.159
0.938 ± 0.050
0.474 ± 0.174
0.750 ± 0.147
0.920 ± 0.056
0+ = number of patients With 2:50% diameter narrowing of at least one major coronary artery; 0 coronary arteries, SO = standard deviation
of the patient's age, sex and symptoms, we (3,4) recently reported
an excellent linear correlation (r = 0.96; probability [p] <0.001)
between the probability of disease and its empiric angiographic
prevalence in 8,192 patients.
Table I summarizes our personal experience with this symptom
classification in 132 consecutive symptomatic patients who were
catheterized for the purpose of diagnosing coronary artery disease.
The probability of disease was calculated for each patient by analysis of age, sex and symptom class as a continuous function derived
from previously published data (5,6) on more than 15,000 symptomatic patients undergoing angiography. Both probability and
prevalence increased in parallel as the symptom class' 'worsened."
Within each symptom class, there was no significant difference
between the prevalence predicted by probability analysis and that
observed at angiography. Analysis of the probability density functions for these data (6) supports the conclusion that this chest pain
classification accurately defines patient subsets with clinically important differences in angiographic disease prevalence (Fig. I).
As a basis for reference, then, Table 2 summarizes the probability
for coronary artery disease according to age, sex and symptom
classification as predicted from our current computerized data base
(5).
We believe, therefore, that explicit characterization of the pres-
=
number of patienls With <50% diameter narrowing in all major
ence and quality of chest discomfort as described herein satisfies
the physician's requirement of a clinically relevant, effective means
for estimating each patient's risk for coronary artery disease.
GEORGE A. DIAMOND, MD
Cardiac Stress Laboratory
Cedars-Sinai Medical Center
8700 Beverly Boulevard
Los Angeles. California 90048
References
Sanunga JT Iriabihty of a chest pain history quesnonnaire to predict coronary
disease in the exercise laboratory (letter). Am J Cardiol 1982;50:1084-5
2 Diamond GA. Forrester JS, Hirsch M, et al. Application of conditional probabihty
analysis to the clinical diagnosis of coronary artery disease. J Chn Invest
1980;65.1210-1
3. Chairman BR, Bourassa MG, DaVIS K, et al. Angiograpluc prevalence of high
nsk coronary artery disease in patient subsets (CASS). Circulation 1981,64.360
4. Diamond GA, Forrester JS Probabihty of CAD (letter) CIrculation 1982;65:641
5 Diamond GA CADENZA: Computer-assisted diagnosis and evaluation of coronary artery disease. 1979: Seattle, Cardiokinencs, (software and documentation
magnetic tape).
6 Diamond GA, Forrester JS. Improved mterpretanon of a continuous variable m
diagnostic testing: probabilisnc analysis of scintigraphic rest and exercise left
ventricular ejection fractions for coronary disease detection Am Heart J
1981;102:189-95.
Table 2. Probability of Angiographic Coronary Artery Disease
Age (yr)
AS
NA
TA
AA
Women
35-45
45-55
55-65
65-75
0.007
0.021
0.054
0.115
±
±
±
±
0.006
0.018
0.042
0.078
0.027
0.069
0.127
0.171
± 0.024
± 0.051
± 0.080
± 0.097
0.155
0317
0.465
0.541
0037
0.077
0.111
0.113
±
±
±
±
0.024
0.040
0.049
0.050
0.105
0.206
0.282
0.282
± 0.063
± 0.090
± 0.100
± 0.100
0428
0.601
0.690
0.700
± 0.174
± 0.169
0.454
0.677
0.839
0.947
±
±
±
±
±
±
±
±
0.809
0.907
0.939
0.943
± 0.104
± 0.049
± 0.029
± 0.026
± 0.111
± 0.160
0.186
0167
0.108
0.055
Men
35-45
45-55
55-65
65-75
0.144
0.129
0.106
0.103
Each estrmate IS the average disease probability (± 1 standard deviauon) over the mdicated age range assuming average levels for the conventional Framingham risk
factors AA = atypical angina. AS = asymptomatic. NA = nonangmal discomlort. TA = typical angina
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