[Implementation of the new diagnostic criteria for myocardial infarction].

Abstract

The extent of implementation in daily clinical practice of the new definition of myocardial infarction is unknown. The purpose of the present study was to describe the use of the new definition in patients discharged from a cardiology department. We analyzed the clinical records of 277 patients admitted because of acute coronary syndromes and discharged from the cardiology department between 1 March 2001 and 31 August 2001. The final clinical diagnosis based on the presence of classical or only new diagnostic criteria was studied. 127 patients (46%) satisfied the new definition (61% classical criteria and 39% only new criteria). Only 98 (77%) of the patients with myocardial infarction according to the new definition were discharged with this diagnosis (96% of the group that satisfied classical criteria and 48% of the group that satisfied only new criteria). The diagnosis of myocardial infarction is still based predominantly on classical criteria; the new criteria have been only partially implemented.

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135
Rev Esp Cardiol 2003;56(9):923-7
923
The extent of implementation in daily clinical practice of
the new definition of myocardial infarction is unknown.
The purpose of the present study was to describe the use
of the new definition in patients discharged from a
cardiology department.
We analyzed the clinical records of 277 patients
admitted because of acute coronary syndromes and
discharged from the cardiology department between 1
March 2001 and 31 August 2001. The final clinical
diagnosis based on the presence of classical or only new
diagnostic criteria was studied. 127 patients (46%)
satisfied the new definition (61% classical criteria and
39% only new criteria). Only 98 (77%) of the patients with
myocardial infarction according to the new definition were
discharged with this diagnosis (96% of the group that
satisfied classical criteria and 48% of the group that
satisfied only new criteria). The diagnosis of myocardial
infarction is still based predominantly on classical criteria;
the new criteria have been only partially implemented.
Key words: Myocardial infarction. Diagnosis. Troponin.
Full English text available at: www.revespcardiol.org
Ischemic Heart Disease and Coronary Care Units of
the Spanish Society of Cardiology showed that 42% of
Spanish cardiologists rarely or never applied the
NDMI.5Currently, we do not know how widely the
NDMI is used. However, the variety of ways in which
the NDMI is interpreted must mean that neither
population studies nor healthcare plans reflect the
realities of myocardial infarction (MI). This may well
lead to incorrect conclusions and misguided patient
management strategies.
In this study we describe the extent to which the
NDMI is used in daily clinical practice.
PATIENTS AND METHOD
Cross-sectional, observational study of patients
discharged from the cardiology department of a
INTRODUCTION
The Joint European Society of Cardiology/American
College of Cardiology Committee’s (ESC/ACC) new
definition of myocardial infarction (NDMI)1has
important clinical, epidemiologic, legal and scientific
implications.2
Moreover, it has been seriously
questioned since its publication in 2000.3,4In Spain,
the survey carried out by the Working Group on
BRIEF REPORT
Implementation of the New Diagnostic Criteria
for Myocardial Infarction
Ramón López-Palop, María J. Antolinos, Eduardo Pinar, Daniel Saura, Juan A. Ruipérez,
and Mariano Valdés
Servicio de Cardiología. Hospital Universitario Virgen de la Arrixaca. El Palmar. Murcia. Spain.
Part of this report was presented at the XXXVIII Congreso de
Enfermedades Cardiovasculares (XXXVIII Conference on Cardiovascular
Diseases), Madrid, October 2002.
Correspondence: Dr. R.F. López Palop.
Ricardo Gil, 20, 3° dcha. 30002 Murcia. España.
E-mail: mlopezs@meditex.es
Received 23 January 2003.
Accepted for publication 29 May 2003.
Utilización de los nuevos criterios diagnósticos
de infarto de miocardio
La nueva definición del infarto de miocardio tiene
implicaciones en múltiples campos de la cardiología. Su
grado real de aplicación es actualmente desconocido.
Este trabajo se propone conocer la utilización de la nueva
definición en los pacientes dados de alta de un servicio
de cardiología.
Analizamos el historial clínico de los 277 pacientes
dados de alta de un servicio de cardiología entre el 1 de
marzo y el 31 de agosto de 2001 tras ingresar por un
síndrome coronario agudo.
diagnóstico final atendiendo al cumplimiento de los
criterios clásicos o actuales de infarto. Cumplieron la
nueva definición 127 pacientes (46%), 61% con criterios
clásicos y 39% sin ellos. Sólo 98 (77%) de los pacientes
con infarto según la nueva definición recibieron este
diagnóstico en el momento del alta hospitalaria (el 48% si
no existían criterios clásicos de infarto). Los criterios
clásicos siguen siendo determinantes para el diagnóstico
del infarto de miocardio. Los nuevos criterios se aplican
sólo parcialmente.
Estudiamos el juicio
Palabras clave: Infarto de miocardio. Diagnosis.
Troponina.

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university hospital in Murcia, sSoutheastern Spain.
Patients
Between March 1 and August 31 2001, 277 patients,
diagnosed on admission with suspected acute coronary
syndrome (ACS), were discharged. We reviewed their
clinical records and excluded 150 patients who did not
satisfy the NDMI (Table 1). The final sample consis-
ted of 127 patients.
Definitions and variables
We divided our sample into two groups: group A
patients met both traditional MI diagnostic criteria
(Table 2) and the NDMI; group B patients met only
NDMI criteria.
We considered increases in the following enzymes
as significant when accompanied by a characteristic
rise and fall typical of MI: CPK≥300 ng/dL; CPK-MB
mass≥5 ng/dL; cardiac troponin T≥0.1 ng/dL.
We included patients in the sample when the
diagnosis on admission either used the term MI
explicitly or included a term synonymous with
myocardial necrosis.
Statistical analysis
Quantitative variables are expressed as the mean and
SD. We constructed a logistical regression model to
identify variables independently associated with a
hospital discharge diagnosis of MI. We analyzed data
with SPSS 11.0 for Windows.
RESULTS
Of the 127 patients discharged during the period of
our study after MI as defined by the NMDI, 77 also met
classical criteria for MI (61%, group A). The remaining
50 patients (39%) presented isolated elevated levels of
the new markers, cardiac troponins or MB mass (group
B). Baseline characteristics of groups Aand B appear in
Table 3. Table 4 shows clinical characteristics of MI
presentation. Group
significantly greater ischemic abnormalities in the ECG,
peak CPK and duration of symptoms. Table 5 shows the
patients’ hospital course and diagnostic and therapeutic
tests on admission. We found no differences between
diagnostic tests except for a significantly greater use of
coronary angiography in Group A. Group A patients
showed significantly greater use of reperfusion
A showed
924
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López-Palop R, et al. Implementation of the New Diagnostic Criteria for Myocardial Infarction
TABLE 1. New definition of myocardial infarction
(ESC/ACC)
Criteria for acute, evolving or recent MI
Either of the following criteria is diagnostic for acute, evolving or
recent MI:
1. Typical increase and decrease in biochemical markers of
myocardial necrosis (cardiac troponins and CPK-MB), with at
least one of the following:
– Typical symptoms of myocardial ischemia
– Development of new Q waves on the ECG
– ECG changes indicative of myocardial ischemia
– Coronary artery intervention (percutaneous or surgical)
2. Pathologic findings of an acute MI
Criteria for established MI
Any one of the following criteria:
1. Development of new Q waves on serial ECG. The patient may or
may not remember previous symptoms. Biochemical markers of
myocardial necrosis may have normalized, depending on the time
that has passed since the infarction developed
2. Pathologic signs of a healed or healing MI
ESC indicates European Society of Cardiology; ACC, American College of
Cardiology.
TABLE 2. Classical definition of myocardial infarction
(WHO)
Presence of at least two of the following criteria:
1. Typical symptoms of myocardial ischemia
2. Enzyme increase characteristic of myocardial necrosis
3. ECG changes typical of development of new Q waves
WHO indicates World Health Organization.
TABLE 3. Clinical histories and baseline
characteristics for MI diagnosis groups. Group A:
diagnosis according to classical criteria. Group B:
diagnosis according to new criteria
Group A
N=77
n (%)
Group B
N=50
n (%)
P
Age, years*
Women
Cardiovascular risk factors
Smoking
Hypertension
Hypercholesterolemia
Diabetes
Family history
History of previous heart disease
Myocardial Infarction
Angina
Coronary revascularization
Percutaneous
Surgical
Congestive heart failure
Intermittent claudication
Cerebrovascular accident
Chronic bronchial disease
66±11
26 (34%)
67±11
13 (26%)
.69
.35
27 (35%)
40 (52%)
35 (46%)
24 (31%)
9 (12%)
16 (32%)
34 (68%)
25 (54%)
20 (40%)
8 (6%)
.7
.07
.3
.31
.5
13 (17%)
20 (26%)
20 (40%)
23 (46%)
.004
.03
6 (7%)
3 (4%)
4 (5%)
5 (7%)
3 (4%)
11 (14%)
13 (26%)
2 (4%)
5 (10%)
7 (14%)
8 (4%)
2 (4%)
.002
.98
.3
.2
.3
.06
*Mean±SD.

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treatment,
revascularization, and longer average hospital stay. The
diagnosis of MI by imaging techniques was successful
significantly more frequently in group A than group B
(91% vs 60%; P<.0005). The diagnosis of MI at
discharge was recorded for 98 patients (77% of the
sample); 74 (96%) of them were from group A and 24
(48%) from group B (Figure 1). Eight patients showed
increased enzyme levels after coronary angioplasty but
only 3 (37.5%) of them of were diagnosed as having MI
after the procedure. All three belonged to group A.
Diagnoses in the 29 patients not classified as
suffering from MI appear in Figure 2.
According to the multivariate analysis, belonging to
group A, confirmation of MI by imaging techniques,
and acute ischemic abnormalities in the ECG were
associated independently with a greater likelihood that
the specialist would classify events as MI (Table 6).
We developed a model that accounted for 92% (CI
95%, 88%-97%) of the clinical diagnoses of MI (area
below the [ROC] curve).
greater frequency of percutaneous
DISCUSSION
Our results show how little the NDMI has influen-
ced the criteria for diagnosis at discharge from the
cardiology department of our university hospital. Of
127 patients who satisfied the NDMI, 77% were
diagnosed accordingly at discharge versus only 48%
of patients added by applying the new definition.
The prevalence of MI among patients discharged
after admission for ACS was 35% in our sample.
This is 24% less that it would have been (46%) if the
NDMI had been rigorously applied. The ESC/ACC
committee predicted an increase in the number of
infarctions diagnosed by applying NDMI criteria1
López-Palop R, et al. Implementation of the New Diagnostic Criteria for Myocardial Infarction
137
Rev Esp Cardiol 2003;56(9):923-7
925
Fig. 1. Distribution of final clinical diagnoses in discharge reports for
group A, group B and groups A and B together.
96%
48%
77%
0
20
40
60
80
100
100% 100% 100%
Classical
criteria
(group A)
(n=77)
New definition
only
(group B)
(n=50)
AMI in line
with NMDI
(n=127)
Percentage
Meeting criteria
Diagnosis at discharge
TABLE 4. Characteristics of presentation of infarction
by MI diagnosis group. Group A: diagnosis according
to classical criteria. Group B: diagnosis according to
new criteria
Group A
N=77
n (%)
Group B
N=50
n (%)
P
Admission for chest paina
Duration of symptoms
of MIb
MI following coronary
angioplasty
ECG changes indicating
acute ischemia
None
T Wave
ST segment depression
ST segment elevation
Appearance of Q wave
Peak CPKb
Peak MBb
Peak cardiac troponin Tb,d
Peak cardiac troponin Ib,d
71 (92.2%)45 (90%) .7
120 (50-180)60 (30-90) <.0005
4 (5.2%)4 (8.0%) .5
11 (14.3%)
12 (15.6%)
7 (9.1%)
47 (61.0%)
59 (76.6%)
681 (398-1421) 165 (67-246)
91 (36-166)
—
—
18 (36.0%)
7 (14.0%)
16 (32.0%)
9 (18.0%)
0 (0.0%)
.004c
<.0005
<.00058 (4.2-27.4)
0.3 (0.1-1)
3.2 (1.3-9.2)
aChest pain versus all other criteria. bMedian (25th-75th percentiles). cNone
versus any ischemic change observed on the ECG. cCardiac troponins were
not found in patients with ST segment elevation (the majority of patients in
group A).
TABLE 5. Hospital couse and MI management by MI
diagnosis group. Group A: diagnosis according to
classical criteria. Group B: diagnosis according to
new criteria
Group A
N=77
n (%)
Group B
N=50
n (%)
P
Diagnostic tests
Echocardiogram
Isotopic test
Coronary angiogram
Confirmation of coronary
heart diseasea
Number of diseased
vesselsb
0
1
>1
Percutaneous coronary
revascularization
Reperfusion therapy
Thrombolysis
Primary angioplasty
Average length of hospitalization
in daysc
MI diagnosis imaging
Maximum Killip Class >1
Reinfarction
74 (96.1%)
6 (7.8%)
64 (83.1%)
46 (92.0%)
2 (4.0%)
33 (66.0%)
.3
.4
.047
62 (80.5%) 31 (62.0%) .069
1.6 (0.7%)
1 (1.6%)
33 (51.6%)
30 (56.8%)
1.8 (1%)
2 (6.1%)
14 (42.4%)
17 (51.5%)
.3
59 (76.6%)
33 (42.9%)
4 (12.2%)
29 (87.8%)
27 (54.0%)
2 (4.0%)
1 (50.0%)
1 (50.0%) <.0005
.008
<.0005
.4
9 (7-13)
70 (90.9%)
16 (20.8%)
1 (1.2%)
7 (5-10)
30 (60.0%) <.0005
6 (12.0%)
0 (0.0%)
.003
.2
.4
aPercent diameter stenosis ≥75%. bIn patients who underwent coronary
angiography. cMedian (25th-75th percentiles).

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and highlighted this in subsequent research.6,7This
confirms the impact of the NDMI on epidemiologic
data, distribution of healthcare resources and patient
management.
Our data, which reflect the actual level of
implementation of the NDMI criteria, support the
opinion of Spanish cardiologists expressed in a
recent survey.5In our sample, patients who did not
meet classical criteria for the diagnosis of MI had
similar clinical antecedents,
significantly lower frequency of a history of
ischemic heart disease, and fewer clinical symptoms
(lower frequency of ECG changes, duration of
symptoms, peak enzyme
hospitalization). In addition, hospital discharge
diagnoses may have been more strongly conditioned
by the smaller number of cases of infarction that
were confirmed with
Essentially, we were dealing with smaller infarctions
according to the generally accepted grading system
of infarction size. Moreover, these myocardial
infarctions were clinically less important in terms of
hospital course. The multivariate model we cons-
tructed explained 92% of the decisions (ROC). In
the model, the presence of ischemic abnormalities in
the ECG, including those defined by criteria not
contemplated by the ESC/ACC joint committee such
as confirmation of MI with imaging techniques,
were the main factors that conditioned the final
diagnosis of MI in patients with increased enzyme
levels but with none of the traditionally recognized
symptoms of MI. We found that the presence of new
except for the
levels, length of
imaging techniques.
markers of necrosis (cardiac troponins or CK-MB)
together with symptoms of myocardial ischemia was
not sufficient in the majority of patients for the
specialist to establish a final diagnosis of MI at
discharge.
Limitations
Our study is based on a single department, so the
results may not be representative of other centers in
Spain. The lack of prior agreement on the
implementation of the NDMI within our hospital,
where 5 or more specialists make diagnoses
independently, suggests that NDMI use may be similar
in other Spanish centers.
Our study covers a period of 6 months. With time,
results might change, and use of the NDMI might
increase or decrease. We do not believe this
invalidates our results; rather, it reinforces one of our
conclusions: the variety of ways in which the NDMI
is implemented will not only make it more difficult
to compare centers, but will also complicate
comparisons within a single center at different
periods of time.
CONCLUSIONS
Implementation of the NDMI for hospital discharge
diagnoses is limited. This definition is used for fewer
than 50% of patients who do not meet classical criteria
for the diagnosis of MI. Ischemic abnormalities in the
ECG and diagnosis with imaging techniques are the
principal factors that lead to the presenting event being
considered MI in patients who do not meet classical
MI criteria.
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López-Palop R, et al. Implementation of the New Diagnostic Criteria for Myocardial Infarction
Fig. 2. Final clinical diagnoses in discharge reports of patients not
diagnosed as having myocardial infarction even though they met the
criteria in the new definition
57%
27%
7%
3%3%3%
Unstable angina
Acute coronary syndrome
Chest pain
Secondary angina
Angina + increased level of enzymes
Intra-stent restenosis
TABLE 6. Results of multivariate analysis (logistic
regression) of variables associated with diagnosis of
acute myocardial infarction at discharge
Odds ratio 95% CIP
Age, by year
Women
MI by imaging technique
Classical criteria (group A)
ECG changes indicating acute
ischemia
Confirmed coronary
heart disease
Length of hospitalization, days
0.95
0.80
6.15
22.48
0.89-1.00
0.20-3.20
1.73-21.84
5.04-100.29
.062
NS
.005
<.0005
6.16 1.75-21.73.005
0.43
1.04
0.11-1.64
0.95-1.15
NS
NS
MI indicates acute myocardial infarction.
Area below the ROC curve of the model: 0.92 (0.88-0.97).

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