CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 9, October 2012
496
AFRICA
elevation,
13
indicate that pPCI is the preferred reperfusion strategy
in AMI patients when performed by an experienced team as soon
as possible after first medical contact. The pPCI reperfusion
modality remains superior to immediate thrombolysis, even if
transfer to an angioplasty centre is necessary.
Similarly, an early invasive strategy with early coronary
angiography and revascularisation has become the preferred
approach for patients with NSTEMI.
14-17
Additionally, the ESC
guidelines for the diagnosis and treatment of non-ST-segment
elevation acute coronary syndromes (ACI) appropriately
recognises AMI with ongoing or recurrent chest pain and
ST-segment depression as the highest risk subgroup and is an
indication for emergency coronary angiography, followed by
revascularisation, when appropriate.
18
From the sub-analysis of
two previously published trials
19,20
and a meta-analysis,
21
it has
been shown that the greatest benefit of early invasive treatment
was found in patients with elevated cardiac enzymes and
ST-segment changes, i.e. in patients with STDMI.
The aim of this study was to analyse a large group of AMI
patients presenting with different ECG records and to assess the
similarities and differences between baseline and angiographic
characteristics, to assess in-hospital management and mortality,
and to test the hypothesis that an emergency PCI strategy
should be used in both ST-segment elevation MI as well as in
ST-segment depression MI.
Methods
This retrospective, multicentre, observational registry included a
total of 6 602 consecutive patients admitted to five participating
centres (four in the Czech Republic and one in Bulgaria; all
university-type hospitals with catheterisation facilities) for an
acute myocardial infarction during a three-year recruitment
period (except for the centre in Bulgaria, where the recruitment
period was only one year). All participating hospitals followed
the guidelines of the Czech Society of Cardiology.
All patients underwent emergency coronary angiography
(
CAG). Patients with STEMI, new left bundle branch block
(
LBBB) or right bundle branch block (RBBB) and STDMI with
ongoing chest pain underwent CAG immediately after hospital
arrival. In all remaining cases, the procedure was performed
within 24 hours of onset of AMI symptoms. Subjects had to be
18
years or older.
Based on admission ECG records, patients were divided into
one of five subgroups: ST-elevation AMI (
n
=
3446; 52.2%),
ST-depression AMI (
n
=
907; 13.7%),
LBBB AMI (
n
=
241;
3.7%),
RBBB AMI (
n
=
338; 5.1%),
other baseline ECG AMI
(
n
=
1670; 25.3%).
STEMI was defined as new ST-elevation at
the J-point in two contiguous leads with cut-off points of
≥
0.2
mV in men or
≥
0.15
mV in women in leads V2–3 and/or
≥
0.1
mV in other leads. STDMI was defined as a new horizontal
or down-sloping ST depression
≥
0.05
mV in two contiguous
leads or transient ST-segment elevations. The other ECG group
represented all remaining ECG patterns excluding STEMI,
STDMI, LBBB and RBBB.
Patients entered into the registry were admitted for an acute
myocardial infarction using only the ESC/ACC myocardial
infarction redefinition.
22
Symptoms consistent with ischaemia,
new ECG changes and a typical rise and fall of cardiac enzymes
levels (troponin I and/or T and/or creatine phosphokinase-MB)
were mandatory for inclusion. Moreover, the diagnosis of MI had
to be confirmed at the time of discharge from hospital.
Baseline characteristics, such as age, gender, diabetes
mellitus, history of previous myocardial infarction, Killip class
on admission and ECG pattern (including information regarding
any bundle branch blocks – old, new or of unknown origin) were
analysed. Coronary angiographic (or autopsy) data were analysed
to estimate the number of diseased major coronary arteries, to
identify the infarct-related artery (IRA), and assess thrombolysis
in myocardial infarction (TIMI) flow in the infarct-related artery
before and after PCI (whenever PCI was performed).
To identify the ejection fraction, pre-discharge echo-
cardiographic examinations were performed. Revascularisation
strategies used during the index hospital stay were studied.
Patients were followed until transfer to a referral hospital
or hospital discharge/death. Death was defined as all-cause
mortality during hospitalisation. The in-hospital mortality was
also analysed.
Statistical analysis
Patients with STEMI and STDMI were compared based
on demographics, medical history and risk factors, infarct-
related artery and segment, initial and post-procedural TIMI
flow, reperfusion success and in-hospital mortality. Statistical
comparisons between subgroups were performed using
Chi-square and Fisher’s exact tests for categorical variables; data
are expressed in percentages.
Continuous variables are presented as means
±
standard
deviations and were compared using the two-sample Student’s
t
-
test. For ordinary variables, the Mann–Whitney test was
applied. All tests were two-tailed, and a
p
-
value
<
0.05
was
considered statistically significant.
A logistic regression model was used to adjust the differences
in mortality for covariate effects. The following factors and
covariates were used in the model: age, gender, previous diabetes
and myocardial infarction, Killip class
>
I on admission, and
pre-discharge ejection fraction.
Results
During the study period, a total of 6 602 patients were enrolled
in the registry from five participating centres. There were 3 446
patients with STEMI and 907 with STDMI. Patients presenting
with STEMI were younger than those with STDMI. The mean
age in the STEMI group was 64.5 years and in the STDMI group
69.5
years (
p
<
0.001).
There were more patients under 75 years
in the group with STEMI than in the STDMI group (74.5 vs
63.6%,
p
<
0.001).
Compared to STEMI patients, STDMI patients were more
likely to have a history of a previous MI (STDMI 29.3% vs
STEMI 13.8%,
p
<
0.001)
and diabetes mellitus (36.8 vs 24.1%,
p
<
0.001).
The gender distribution was equal between the
STEMI and STDMI groups (females 31.3 vs males 34.6%,
p
=
0.055).
Patients in the STEMI group were more likely to be in
cardiogenic shock on admission. Killip class IV on admission
was present in 6.7% of STEMI patients compared to 4.4% in
STDMI patients (
p
<
0.001).
Acute heart failure defined as Killip
class
>
1
on admission (pulmonary rales or third heart sound and
pulmonary oedema) was present in 29.5% of STDMI vs 27.4%
of STEMI patients (
p
<
0.001) (
Table 1).
