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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 5, September/October 2020
AFRICA
253
universal definition of myocardial infarction as new ST elevation
at the J point in at least two contiguous leads of 2 mm (0.2 mv)
in men or 1.5 mm (0.15 mv) in women in leads v2–v3 and/or of
1 mm (0.1 mv) in other contiguous chest leads or the limb leads.
9,10
In the spectrum of ACS, USAP/NSTEMI was defined
by electrocardiographic ST-segment depression or prominent
T-wave inversion and/or positive biomarkers of necrosis (e.g.
troponin) in the absence of ST-segment elevation and in
an appropriate clinical setting (chest discomfort or anginal
equivalent).
11
NSTEMI was diagnosed by the presence of
positive cardiac enzymes, whereas USAP was not associated with
elevated cardiac biomarkers.
Pamukkale University hospital is a tertiary centre having
the capability of coronary angiography and PCI 24 hours a
day, seven days a week. Patients with a suspicion of ACS were
evaluated by emergency department physicians and cardiologists
until the final diagnosis.
Patients’ demographic and clinical features, and laboratory
parameters were obtained retrospectively from the hospital
database. Hypertension was defined as documentation of a
systolic blood pressure of 140 mmHg and/or a diastolic blood
pressure of 90 mmHg in at least two measurements or active use
of any antihypertensive agent. Diabetes mellitus was defined as
a fasting plasma glucose level over 126 mg/dl (6.99 mmol/l) or
glucose level over 200 mg/dl (11.1 mmol/l) at any measurement
or active use of an antidiabetic agent. Smokers were defined as
patients who continued smoking at presentation.
All patients got in-hospital medication according to current
guidelines.
12,13
A loading dose of 300 mg acetylsalicylic acid was
given to all patients after the diagnosis of ACS. Clopidogrel (300
or 600 mg loading dose) or ticagrelor (180 mg loading dose)
were given in addition to acetylsalicylic acid according to the
preference of the patient’s physician. Unfractionated heparin
or low-molecular weight heparin were given according to the
patient’s weight.
The decision to perform coronary angiography and the timing
of the procedure were determined by the patient’s physician. The
standard Judkins technique was used for visualisation of the
coronary arteries. In-hospital and long-term mortality data were
obtained from hospital records and national mortality records.
The primary endpoint was defined as all-cause mortality at
the prespecified time points. These were: short term (30-day
mortality), midterm (T1), defined as the time between 31 days
and six months, T2, defined as the time between 31 days and 12
months, and long term, defined as the time period beyond 12
months.
Statistical analysis
The analyses were carried out using the SPSS 24 (SPSS Inc,
Chicago, IL). To test the distribution pattern, the Kolmogorov–
Smirnov and Shapiro–Wilk methods, and Skewness and Kurtosis
results were used. Continuous data, which were not distributed
normally, are presented as median
±
interquartile range (IQR);
categorical variables are given as percentages. Categorical
variables were compared with the chi-squared test. Yates’
correction was used where necessary. Fisher’s exact test was
used when expected frequencies were
≤
5. Continuous variables
were compared with the Mann Whitney
U
-test. Cox regression
analysis was used to assess the effect of the strategy on mortality
rate. All parameters in the univariate analysis, which has a
p
-value
<
0.25 and variables, which are the known risk factors of
coronary artery disease, were selected in the multivariate model.
A
p
-value of
<
0.05 was considered statistically significant.
Results
A total of 156 patients (80 male, 51.2%) with a median age of
83
±
5 years were included in this study. Ninety-four of 156
patients (60.3%) underwent coronary angiography and they
constituted the invasive-strategy group, whereas the remaining
62 (39.7%) were treated medically and they constituted the
conservative-strategy group. In the invasive group, 54 (34.6%)
patients underwent PCI, 18 (11.5%) underwent coronary artery
bypass grafting (CABG) surgery and the remaining patients did
not undergo revascularisation because their lesions were not
amenable to either the percutaneous or surgical procedure.
Patients’ demographic features and clinical characteristics are
presented in Table 1. Patients in the invasive group were younger
and more were hypertensive than patients in the conservative
group (
p
=
0.002 and
p
=
0.015, respectively). Serum creatinine
levels at admission were significantly higher in the conservative-
strategy group (1.1
±
0.6 vs 0.9
±
0.4 mg/dl,
p
=
0.042). However
there was no difference in terms of cardiac enzymes or GRACE
risk scores between the groups. Compared with the conservative
group of patients, the invasive group presented more often with
classical ACS symptoms such as chest pain (89.4 vs 69.4%,
p
=
0.002), while they had dyspnoea or other symptoms less
frequently (10.6 vs 30.6%,
p
=
0.002).
Median follow-up duration of patients was 8.5 (0–61) months.
A total of 16 (17%) patients in the invasive group and 24 (38.7%)
in the conservative group died during the one-year follow up (
p
=
0.004) (Fig. 1). Mortality rates at the prespecified time points are
reported in Table 2. Total mortality at the end of the follow-up
period was 24 (25.5%) patients in the invasive-strategy group and
30 (48.4%) in the conservative-strategy group (
p
=
0.006) (Fig. 2).
Eighty-two (52%) patients had coronary artery disease history
before the enrollment and 28 (34%) of them died during follow
up. Seventy-four patients (48%) had no coronary artery disease
history and 26 (35%) of them died during follow up. There
was no statistically significant difference regarding presence of
coronary artery disease and mortality (
p
=
0.897).
Two models were generated in Cox regresssion analysis to find
factors related to mortality. The models and included factors are
presented in Table 3. According to model 1, the invasive strategy
[odds ratio (OR): 0.25, 95% confidence interval (CI): 0.08–0.74,
p
=
0.012], male gender (OR: 3.93, 95% CI: 1.36–11.35,
p
=
0.011), presence of hypertension (OR: 2.65, 95% CI: 1.11–6.32,
p
=
0.027), low ejection fraction below 40% (OR: 4.49, 95% CI:
1.66–12.10,
p
=
0.003), GRACE risk score below 150 (OR: 0.18,
95% CI: 0.03–0.86,
p
=
0.032) and sinus rhythm at admission
electrocardiography (ECG) (OR: 0.21, 95% CI: 0.05–0.85,
p
=
0.029) were found to be related to long-term mortality rate.
According to model 2, the invasive strategy (OR: 0.26, 95%
CI: 0.12–0.56,
p
=
0.001), presentation with STEMI (OR: 7.76,
95% CI: 1.74–34.57,
p
=
0.002), low ejection fraction below 40%
(OR: 3.11, 95% CI: 1.43–6.76,
p
=
0.004), heart rate (OR: 0.98,
95% CI: 0.96–0.99,
p
=
0.013) and GRACE risk score between
150 and 170 (OR: 7.76, 95% CI: 1.74–34.57,
p
=
0.002) were
related to long-term mortality rate.