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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 4, July/August 2016
AFRICA
219
admission, anterior myocardial infarction, and the combination
of hypotension and tachycardia. The GRACE risk model assists
in risk profiling and hence prioritising care.
13,14
The Nairobi Hospital has a well-equipped emergency
department and intensive care unit (ICU), and a modern cardiac
catheterisation laboratory with well-trained staff. At the Nairobi
Hospital, fibrinolytic therapy is the treatment of choice for
STEMI. Primary PCI is increasingly used however it is not yet
available timeously and consistently at all hours, due to various
logistical factors.
This was a retrospective study of the Nairobi Hospital
ICU and high-dependence unit (HDU) in-patient records to
describe the demographics, risk factors, clinical characteristics,
management and outcomes of patients diagnosed with acute
myocardial infarction admitted to the Nairobi Hospital ICU and
HDU from January 2007 to June 2009.
Methods
The hospital ethics committee gave consent for the study.The
in-patient patients’ records were retrieved and a cardiologist
verified the diagnosis of STEMI and NSTEMI, after which
the pre-specified data variables were retrieved and filled into a
pre-designed study pro forma.
Patients who presented with a diagnosis of acute myocardial
infarction and were over 18 years were included. STEMI was
defined according to the European Society of Cardiology
guidelines, as patients with acute chest pain and persistent (
>
20
minutes) ST-segment elevation at the J-point in two contiguous
leads with the cut-off points:
≥
0.2 mV in men or
≥
0.15 mV
in women in leads V2–V3 and/or
≥
0.1 mV in other leads. For
the purposes of reperfusion strategy, true posterior myocardial
infarction was considered in patients with ST-depression in the
anterior leads or new prominent R waves on the same leads.
15,16
NSTEMI was defined as patients with chest pain but without
persistent ST elevation, new horizontal or down-sloping ST
depression
≥
0.05 mV in two contiguous leads; and/or T
inversion
≥
0.1 mV, flat T waves and pseudo-normalisation of
T waves in two contiguous leads with prominent R wave or R/S
ratio or no ECG changes at presentation. The confirmation of
acute myocardial infarction was made based on elevated cardiac
biomarkers.
15,16
Significant atheromatous lesions were defined as
a left main stem lesion of
>
50% stenosis and lesions involving
the left anterior descending, left circumflex and right coronary
arteries
>
70% stenosis.
We analysed the demographic data, mode of transport to
the accident and emergency department, first medical contact,
time of arrival after onset of chest pain, door-to-first ECG time,
and ECG-to-cardiologist time. The GRACE risk score of each
patient on admission was documented as per the parameters at
admission.
The risk factors for coronary artery disease analysed included
age
>
55 years in men and
>
65 years in women, male gender,
current smoking, low high-density lipoprotein cholesterol (HDL-
C) level
<
40 mg/dl (1.04 mmol/l), systemic hypertension (blood
pressure
>
140/90 or on antihypertensives), diabetes and family
history of premature coronary artery disease.
The initial medication given at the accident and emergency
department, the type of myocardial infarction and the
reperfusion treatment for STEMI were noted. The door-to-
needle time and fibrinolytic agent used were both recorded. The
coronary anatomy and TIMI grade for coronary blood flow were
documented as per the cardiologist’s notes and confirmed by an
interventional cardiologist who studied the digital images of the
coronary angiogram. The in-hospital complications, duration
of hospitalisation, in-hospital deaths and discharge medications
were noted.
Statistical analysis
The extracted data were entered into the Statistical Package
for Social Science
TM
(SPSS) version 13.0 for Windows (SPSS,
Chicago, IL, USA) statistical software to check for errors
and perform the requisite statistical tests. Data were analysed
using the same software. Descriptive analysis was performed to
characterise the number and type of patient outcomes. To obtain
insight into the social demographic factors of the patients,
frequency tables were used with accompanying percentages.
Bivariate comparisons of continuous symmetric character-
istics, such as duration of time between onset of chest pain/
symptoms and arrival at hospital, door-to-first ECG time and
ECG-to-cardiologist time were performed using the Student’s
t
-test and Mann–Whitney test for non-symmetric characteristics
for patients with independent variables (in-hospital outcome).
Fisher’s exact test and the chi-squared test, as appropriate,
were used for comparison of categorical characteristics, such as
gender, coronary artery anatomy and in-hospital complications
with patients’ in-hospital outcomes.
Correlations between variables were tested using the Pearson’s
correlation co-efficient. Prevalence of risk factors was calculated
with accompanying 95% confidence intervals. Statistical
significance was defined as a two tailed
p
-value
≤
0.05.
Results
Sixty-four patients fulfilled the criteria for STEMI and NSTEMI
from January 2007 to June 2009 and 87.5% were male. The
mean age was 56.7 years. Of the study population, 60.9% were
from the community, while 26.6% were referrals from other
health facilities; 28.1% were brought by ambulance but mode of
transport was not documented in 67.2% of the cases. Five per
cent of the patients were already hospitalised and 89.1% had
their first medical contact in hospital. Among the patients, 17.2%
arrived within one hour of onset of chest pain, whereas 40.6%
arrived at the emergency department more than 12 hours after
the onset of chest pain.
The presence of coronary artery risk factors in this population
was as follows: systemic hypertension was found in 71.9% of
patients, 42.2% were over 55 or 65 years in men and women,
respectively, 35.9% were cigarette smokers, 25% had a low
HDL-C level, 25% had diabetes mellitus, 8% had a documented
family history of premature coronary artery disease, 18.8% had
a previous history of acute coronary syndrome and 9.4% had
chronic kidney disease.
The documented door-to-ECG time was less than 10 minutes
in only 10.9% of patients and the ECG-to-cardiologist time was
less than 30 minutes in 36.5%. Both aspirin and clopidogrel
were received by 96.9% of patients on arrival at the emergency
department. A loading dose of aspirin was given in 53.2% of
patients, whereas 62.9% received a loading dose of clopidogrel;